NTIA Report 08-450

POTENTIAL INTERFERENCE FROM 

BROADBAND OVER POWER LINE (BPL) 

SYSTEMS TO FEDERAL GOVERNMENT 

RADIOCOMMUNICATION SYSTEMS 

AT 1.7 - 80 MHz

Phase 2 Study

VOLUME I

technical report

 

 

U.S. DEPARTMENT OF COMMERCE y National Telecommunications and Information Administration

NTIA Report 08-450

POTENTIAL INTERFERENCE FROM BROADBAND OVER 

POWER LINE (BPL) SYSTEMS TO FEDERAL 

GOVERNMENT RADIOCOMMUNICATION SYSTEMS AT 

1.7 - 80 MHz

Phase 2 Study

VOLUME I

James C. Richards

Jonathan V. Williams

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

John M. R. Kneuer, Assistant Secretary

for Communications and Information

October 2007
ACKNOWLEDGEMENTS

 

 

 The authors would like to thank the many organizations and persons who 

contributed to the completion of this report. In particular, we wish to thank the federal 

agency representatives on the Interdepartment Radio Advisory Committee for providing 

vital comments, information, and review of this report. 

 

 We also wish to thank the following NTIA personnel who contributed 

substantially to this report and to the underlying studies: Alakananda Paul Cou-Way 

Wang, and Edward Drocella. 
PREFACE

 This report contains two volumes. Volume I presents the main text and Volume 

II contains appendixes that provide additional technical supporting information that is 

summarized in Volume I. 

 

 
EXECUTIVE SUMMARY

 

 

On October 14, 2004, the Federal Communications Commission (Commission or 

FCC) adopted a Report and Order that defined new Part 15 rules for Access Broadband 

over Power Line (BPL) systems. The National Telecommunications and Information 

Administration (NTIA) contributed to the Commission’s work by providing analysis to 

support recommendations for refinements in the rules and measurement guidelines in 

comments and staff correspondence filed in response to the Commission’s earlier BPL 

Notice of Proposed Rulemaking (NPRM). The NTIA Phase 2 study of Access BPL 

systems expands on its earlier Phase 1 study by providing additional modeling results and 

analyses to evaluate the effectiveness of the FCC’s rules and measurement guidelines in 

minimizing the potential for harmful interference to federal radiocommunication systems 

under worst-case conditions. 

NTIA’s simulations of overhead Medium Voltage (MV) power lines show that 

aspects of the measurement guidelines addressed in the BPL Report and Order, such as 

measurement distance, locations, height and height correction factor, and antenna type, 

effectively estimate the peak electric field strength that might be experienced in the 

vicinity of the Access BPL energized power line. These simulations employ the 

Numerical Electromagnetic Code (NEC) software package to model a variety of power 

line configurations. NTIA investigated the Commission’s new methodology for 

extrapolating field strength limits when measurements must be made at distances other 

than those specified in the rules. NTIA’s simulations confirm that the extrapolation 

methodology provides a reasonable approximation of the predicted rate of field strength 

roll-off with distance in close proximity to the BPL device and its associated power lines. 

The FCC’s rules include special mechanisms for minimizing the likelihood of 

harmful interference to critical federal radiocommunication systems in addition to the 

baseline protection afforded by field strength limits, prohibition of harmful interference 

from Access BPL systems, and compliance measurement provisions. These special 

protection provisions have the following forms: geographic consultation areas, wherein 

BPL deployments at any frequency in those areas must be preceded by consultations 

between BPL operators and nearby radio operators; excluded bands, in which certain 

frequencies are not to be used by BPL in any geographic area; and small geographic 

exclusion zones, wherein BPL emissions are forbidden at specified frequencies. NTIA’s 

analysis shows that, at the distances corresponding to these protection areas, BPL 

emissions are expected to result in only small increases in the noise floor of protected 

communications receivers, or power flux density levels that fall below the interference 

protection requirement for sensitive radioastronomy or over-the-horizon radar receivers. 

This Phase 2 report illustrates the application of the rules and measurement 

guidelines in a case study. Using the NEC software package, NTIA created an elaborate 

power line model that approximates an existing overhead Access BPL power line 

structure. After applying the emissions limits and methodology from the BPL 

measurement guidelines, NTIA analyzed the noise floor increase expected in nearby 

receivers as a result of BPL operations. In addition, NTIA used this power line model to 
analyze the BPL emission levels that might be seen at more distant receivers. The results 

of the case study are consistent with NTIA’s earlier analyses using simple power line 

models. 

NTIA’s Comments in response to the BPL NPRM included a preliminary analysis 

of the aggregation of overhead Access BPL emissions via ionospheric propagation in the 

1.7 to 30 MHz frequency range. That analysis has been further refined in this report to 

include NEC simulations of both an elaborate overhead power line model and an 

underground power line model, and the adopted BPL measurement guidelines were 

employed to ensure compliance with Part 15 rules. As in the earlier analysis, the Voice 

of America Coverage Analysis Program (VOACAP) High Frequency (HF) propagation 

software package was used for predicting the propagation of radiated BPL emissions. 

Ionospheric propagation was analyzed using these overhead and underground models 

over a wide range of conditions. The results of this analysis show that a widespread 

deployment of Access BPL systems throughout the United States is not expected to pose 

a problem for federal radiocommunication systems operating in the 1.7 to 30 MHz band. 

In summary, the Phase 2 study analyses expanded on the scope of NTIA’s earlier 

analyses and applied the Commission’s adopted rules and measurement guidelines for 

Access BPL systems. The results of these analyses confirm that these Access BPL rules, 

measurement guidelines, and special protection provisions will limit the interference risks 

for federal radiocommunication systems. 
 

VOLUME I

TABLE OF CONTENTS

 

 

ACKNOWLEDGEMENTS ................................................................... iii 

PREFACE ...................................................................................... iv 

EXECUTIVE SUMMARY 

.................................................................... 

v 

TABLE OF CONTENTS ...................................................................... vii 

GLOSSARY 

.................................................................................... 

x 

 

 

SECTION 1 INTRODUCTION 

 1.1 Background ............................................................... 1-1 

 1.2 Objectives ................................................................. 1-2 

 1.3 Approach .................................................................. 1-2 

 

SECTION 2 PART 15 MEASUREMENT GUIDELINES 

 2.1 Introduction ............................................................... 2-1 

 2.2 Power Line Models Used in the Analysis ........................... 2-1 

 2.3 Measurement Antenna Height ......................................... 2-5 

 2.3.1 Height Corresponding to Peak Field Strength ...................... 2-5 

 2.3.2 Peak Electric Field Strength at the Compliance Measurement 

Heights........................................................................................... 

 

2-8 

 2.3.3 Antenna Measurement Height Correction Factor above 30 MHz 2-13 

 2.4 Measurement Distance Along the Power Line ....................... 2-17 

 2.5 Measurement Distance Extrapolation ................................. 2-22 

 2.5.1 New Approach for Distance Extrapolation ........................... 2-22 

 2.5.2 Calculated Electric Field Strength Decay for Distance 

Extrapolation ............................................................. 2-26 

 2.6 Use of Loop Antenna Below 30 MHz .............................. 2-29 

 2.7 Measurement Antenna Polarization ................................... 2-30 

 2.8 Guidelines for Choosing Representative Systems .................. 2-31 

 2.9 Summary ................................................................... 2-34 

 

SECTION 3 SPECIAL PROVISIONS FOR PREVENTION OF 

INTERFERENCE FROM BPL SYSTEMS 

 

 3.1 Introduction ............................................................... 3-1 

 3.1.1 Background ............................................................... 3-2 

 3.2 Potential Victim Receivers ............................................. 3-3 

 3.2.1 Communications Receivers ............................................ 3-3 

 3.2.2 Radar Receivers ......................................................... 3-5 
 3.2.3 Radioastronomy Receivers ............................................. 3-6 

 3.3 Potential Sources of Interference ....................................... 3-6 

 3.3.1 Overhead Power Line Model ........................................... 3-6 

 3.3.2 Underground Power Line Model ...................................... 3-7 

 3.3.3 Part 15 Scaling of Power Line Models ................................ 3-8 

 3.4 Analytical Approach ..................................................... 3-9 

 3.4.1 Communications Receivers ............................................ 3-9 

 3.4.2 Radar Receivers ......................................................... 3-11 

 3.4.3 Radioastronomy Receivers ............................................. 3-13 

 3.5 Simulation Results ....................................................... 3-14 

 3.5.1 Communications Receivers ............................................ 3-16 

 3.5.2 Radar Receivers ......................................................... 3-23 

 3.5.3 Radioastronomy Receivers ............................................. 3-23 

 3.6 Summary .................................................................. 3-25 

 

SECTION 4 CASE STUDY OF POTENTIAL INTERFERENCE USING 

ADOPTED BPL RULES 

 

 4.1 Introduction ............................................................... 4-1 

 4.2 Methodology .............................................................. 4-1 

 4.2.1 Structure Injection Points ................................................ 4-2 

 4.2.2 Simulation Frequencies ................................................. 4-3 

 4.2.3 Part 15 Scaling ........................................................... 4-5 

 4.2.4 Simulation of Potential Interference .................................. 4-7 

 4.3 Results ..................................................................... 4-12 

 4.3.1 Receiver Noise Floor Increase Along the Power Line ............... 4-14 

 4.3.2 Power Flux Density Away from the Power Line ..................... 4-16 

 4.4 Summary .................................................................. 4-19 

 

SECTION 5 IONOSPHERIC PROPAGATION AND AGGREGATION OF 

BPL EMISSIONS 

 

 5.1 Introduction ............................................................... 5-1 

 5.2 Analytical Modeling of Sky Wave Propagation ................... 5-1 

 5.2.1 Background ............................................................... 5-1 

 5.2.2 Approach .................................................................. 5-2 

 5.3 Simulation Characteristics .............................................. 5-6 

 5.4 Simulation Results ....................................................... 5-9 

 5.4.1 Comparison of Overhead and Underground Analysis Results..... 5-9 

 5.4.2 Maps of Ionospheric Aggregation ..................................... 5-11 

 5.5 Summary .................................................................. 5-18 

 

SECTION 6 SUMMARY OF RESULTS 

 6.1 Introduction ............................................................... 6-1 

 6.2 Phase 2 Analyses ......................................................... 6-1 

 6.2.1 Part 15 Rules and Measurement Guidelines ......................... 6-1 

 6.2.2 Special Protection Provisions .......................................... 6-3 

 6.2.3 Case Study Applying the Access BPL Measurement Guidelines 6-3 
 6.2.4 Aggregation of Emissions via Ionospheric Propagation ............ 6-4 

 6.3 Conclusion ............................................................... 6-4 

 

TECHNICAL APPENDICES

(See VOLUME II) 

 
 

 GLOSSARY

 

 

AWG American Wire Gauge 

BPL Broadband over Power Line(s) 

BW Bandwidth 

CISPR International Special Committee on Radio Interference 

CONUS Continental United States 

COTHEN Customs Over The Horizon Enforcement Network 

dB Decibel 

dBi Decibel referenced to an isotropic radiator 

dBm Decibel referenced to 1 milliwatt 

dBμV Decibel referenced to 1 microvolt 

dBW Decibels referenced to 1 Watt 

E Electric Field Strength 

EMC Electromagnetic Compatibility 

EUT Equipment Under Test 

FCC Federal Communications Commission 

G Gain 

GHz Gigahertz 

H Magnetic Field Strength 

HF High Frequency 

Hz Hertz 

I Interference Power 

ICAO International Civil Aviation Organization 

IRAC Interdepartment Radio Advisory Committee 

ITM Irregular Terrain Model 

ITS Institute for Telecommunication Sciences 

ITU International Telecommunication Union 

ITU-R International Telecommunication Union Radiocommunication Sector 

kHz Kilohertz 

km Kilometer 

LV Low Voltage 

m Meter 

MHz Megahertz 

mm millimeter 

mS Siemens/meter 

ms Millisecond 

MV Medium Voltage 

N Noise Power 

NEC Numerical Electromagnetic Code 

NOI Notice of Inquiry 

NPRM Notice of Proposed Rulemaking 

NTIA National Telecommunications and Information Administration 

OR Off-Route 
OTH Over the Horizon 

PFD Power Flux Density 

PLC Power Line Communications 

PLT Power Line Telecommunications 

R Route 

RF Radio Frequency 

RMS Root Mean Square 

RSMS Radio Spectrum Measurement System 

S Signal Power 

SNR Signal-to-Noise Ratio 

SSB Single Sideband 

SSN Smoothed Sunspot Number 

URD Underground Residential Distribution 

US&P United States and Possessions 

UTC Universal Coordinated Time 

VHF Very High Frequency 

VLA Very Large Array 

VOA Voice of America 

VOACAP Voice of America Coverage Analysis Program 

W Watt 

μA Microampere 

μV Microvolt 

 
 
SECTION 1 

INTRODUCTION 

1.1 BACKGROUND 

The National Telecommunications and Information Administration (NTIA) Phase 

1 Study of Access Broadband over Power Line (BPL) systems summarized federal use of 

the 1.7 – 80 MHz frequency range, presented measurement and modeling results for BPL 

emissions, defined interference risks to radio reception in the immediate vicinity of 

overhead power lines used by Access BPL systems, suggested refinements to Part 15 

measurement guidelines applicable to BPL systems, and identified means for mitigating 

local interference should it occur.[1] Propagation and aggregation of emissions from BPL 

systems and the associated BPL deployment models were suggested as issues requiring 

further study. 

 

In comments and staff correspondence filed in response to the Federal 

Communications Commission (Commission or FCC) BPL Notice of Proposed 

Rulemaking (BPL NPRM), NTIA provided a preliminary analysis to support 

recommendations for refinements in the rules and measurement guidelines.[2] In its 

comments, NTIA proposed a number of refinements to the measurement guidelines for 

BPL systems, such as the measurement locations along the power line, away from the 

power line, and at various measurement antenna heights. NTIA’s preliminary analysis of 

these proposals confirmed that the measurement guidelines defined in the BPL NPRM 

strike a reasonable balance between measurement simplicity, accuracy and repeatability. 

 NTIA also presented a worst-case analysis of ionospheric propagation and aggregation 

of emissions from wide scale deployment of Access BPL systems. This preliminary 

analysis showed that aggregation of BPL emissions via ionospheric propagation was not 

a near term problem; however, NTIA indicated that it would continue to study this issue. 

Finally, NTIA continued to evolve its analysis of interference risks to nearby radio 

receivers and proposed a framework for protection of critical federal 

radiocommunications. 

1.2 OBJECTIVES 

The NTIA Phase 2 Study is intended to provide additional technical background 

for the rules and measurement guidelines for Access BPL systems. This report combines 

the preliminary Phase 2 analyses presented in other NTIA contributions in the FCC’s 

BPL proceeding with additional analyses that extend both the depth and scope of the 

earlier work. It also offers a case study of calculated emission levels from a model of an 

actual BPL network for the purpose of demonstrating the effectiveness of the BPL rules 

and measurement guidelines adopted by the FCC in its BPL Report and Order.[3] This 

case study includes an analysis of the risk of interference that a representative BPL 

network might present to nearby radiocommunications. 
1.3 APPROACH 

NTIA simulated a variety of power line structures using the Numerical 

Electromagnetic Code (NEC) software package and determined the expected field 

strength over a range of distances from the power line, along the length of the power line, 

and at various heights above the ground.[4] 

The NEC simulations were used to evaluate the effectiveness of the FCC’s 

recently adopted measurement guidelines at achieving a reasonable level of measurement 

accuracy with a practical number of measurements as discussed in Section 2. 

In Section 3, the interference risk to fixed and mobile base station receivers from 

nearby BPL devices was analyzed to formulate suitable radii recommendations for 

exclusion zones and consultation areas. 

Using an NEC model of an elaborate power line structure, NTIA applied the 

measurement guidelines adopted in the BPL Report and Order to evaluate their 

effectiveness as a means to limit the interference risk associated with these emissions to 

nearby radiocommunications as discussed in Section 4. 

Based on the rules and measurement guidelines for Access BPL systems, NTIA 

updated and expanded upon its evaluation of the aggregation of their emissions via 

ionospheric propagation using the Voice of America Coverage Analysis Program 

(VOACAP) High Frequency (HF) propagation software package as discussed in Section 

5.[5] 

Finally, a summary of the results from these analyses is provided Section 6. 

Supplemental data from these analyses are provided in Appendices A through D 

contained in Volume II of this report. 

 

SECTION 2 

PART 15 MEASUREMENT GUIDELINES 

2.1 INTRODUCTION 

In the Phase 1 Study, NTIA stated that adopting effective BPL measurement 

guidelines is critical to reducing the risk of harmful interference to federal 

radiocommunications.[6] The NTIA Phase 1 Study comments on the FCC’s BPL NPRM, 

and subsequent correspondence with the Commission described NTIA’s measurements 

and analyses of BPL emissions.[7] Emissions from Access BPL systems operating on 

overhead Medium Voltage (MV) power lines are atypical of most Part 15 devices in that 

the peak field strength often occurs at heights significantly greater than 1 meter and may 

occur at various distances along the power line. 

 

NTIA’s measurements and analyses showed that the strength of radiated 

emissions diminished more slowly with distance from the BPL source than would be 

expected of a typical point source radiator. Measurements of BPL field strength are 

typically performed in the near field where the relationship between the electric and 

magnetic fields is not easily quantified. In its earlier filings in the FCC’s BPL 

proceeding, NTIA presented measurements and computer modeling of emissions from 

Access BPL sources and connected power lines in order to characterize the nature of 

these emissions. In the Phase 2 Study, NTIA further analyzes these characteristics of 

BPL emissions using the Commission’s recently adopted measurement guidelines to 

demonstrate that these guidelines effectively balance measurement accuracy with a 

reasonably limited number of measurements. 

2.2 POWER LINE MODELS USED IN THE ANALYSIS 

NTIA used the NEC software program to create a number of power line models to 

gain a greater understanding of the effects various physical topologies might have on the 

electric fields radiated by BPL signals on power lines. Below 30 MHz, the magnetic 

field that would be measured by rotating a vertically positioned loop antenna 180 degrees 

about its vertical axis was determined by simulation over a range of heights and all along 

the length of the power line model. Where results below 30 MHz are shown in terms of 

electric field strength, the magnetic field strength was converted to vertical electric field 

strength using Equation 2-1, assuming a Cartesian coordinate system as shown in Figure 

2-1 below: 

 

 

, (Equation 2-1) 

where η is the impedance of free space, nominally 377 ohms (Ω); 
 Hx is the x-component of the horizontal magnetic field, in A/m; 

Hy is the y-component of the horizontal magnetic field, in A/m; and 

Ez is the vertical electric field strength in V/m. 

 

Figure 2-1: Power line and coordinate system

Above 30 MHz, the electric field strength in either the horizontal or vertical polarization 

was determined over a range of heights and at any position along the length of the NEC 

power line models. 

NTIA evaluated a wide variety of power line topologies to calculate three-axis 

electric field values in a vertical grid located at a 10 meter horizontal distance from the 

power line (the measurement distance adopted in the BPL Report and Order), at heights 

ranging from 1 to 20 meters in one meter increments. These calculations were made 

horizontally along the length of the modeled power lines in one meter increments, and at 

frequencies ranging from 2 to 50 MHz in 2 MHz increments. Eighteen relatively simple 

power line topologies are listed in Table 2-1. Figure 2-2 depicts the orientation of power 

line conductors for each of these topologies. 

 

 

 

 

 

 

 

Table 2-1: Power line topologies used to model antenna measurement height

Model 

Name

Number of 

Wires

Wire

Configuration

Multi-grounded neutral 

with 3 transformers

Wire

Spacing
Model 

Name

Number of 

Wires

Wire

Configuration

Multi-grounded neutral 

with 3 transformers

Wire

Spacing

tri26 2 triangular-horizontal not included 0.6 meters

tri210 2 triangular-horizontal not included 1.0 meters

tri36 3 triangular-horizontal not included 0.6 meters

tri310 3 triangular-horizontal not included 1.0 meters

tri26n 2 triangular-horizontal included 0.6 meters

tri210n 2 triangular-horizontal included 1.0 meters

tri36n 3 triangular-horizontal included 0.6 meters

tri310n 3 triangular-horizontal included 1.0 meters

ver1 1 vertical not included n/a

ver26 2 vertical not included 0.6 meters

ver210 2 vertical not included 1.0 meters

ver36 3 vertical not included 0.6 meters

ver310 3 vertical not included 1.0 meters

ver1n 1 vertical included n/a

ver26n 2 vertical included 0.6 meters

ver210n 2 vertical included 1.0 meters

ver36n 3 vertical included 0.6 meters

ver310n 3 vertical included 1.0 meters

 

The power line models listed in Table 2-1 were 340 meters in length, 12 meters 

above ground, and consisted of eight segments of catenary (hanging) wires (with catenary 

lengths of 43 meters each) as would be suspended between nine utility poles. The signal 

injection point for these models was on the segment next to the model’s mid-point, on 

one of the outside wires. All wires were assumed to be copper, and all models with 

neutral wires included three simulated distribution transformers wired between one of the 

phases and neutral, with 7.7 Ω of real impedance.[8] On the models with a neutral wire, 

the neutral was connected to ground at each transformer point (in the center of the model 

and at each end). 

 
Figure 2-2: Power line topologies

 

Vertical-alignment models were designed such that all wires (including the 

neutral, if any) were arranged in a vertical line. Triangular-horizontal models with three 

wires were designed with the middle wire 0.25 meter higher than the outer two. The 

neutral wire (if one was included) was centered under the phase wires. 

 

NTIA also constructed an elaborate NEC model based on the physical layout of 

an actual MV distribution branch in one of the BPL deployment areas where NTIA 

conducted field measurements. This model was designed using power line maps as well 

as actual observation (Figure 2-3). The model consisted of three-phase and multigrounded neutral wiring. Included in the model are risers (connections of all three phases 

of overhead wiring to underground wiring having a characteristic impedance of 30 Ω), 

wire intersections, transformers and neutral grounds. Along most of the power line, the 

wiring topology is vertical, but at one pole (at a riser) it shifts to a horizontal-triangular 

configuration and then back to vertical. The model covered an area of some 240,000 

square meters (600m × 400m), and was segmented and tested at 4.303 MHz, 8.192 MHz, 

22.957 MHz and 28.298 MHz (frequencies which corresponded with measurement 

frequencies in the field). 

 
Figure 2-3: NEC model of actual power line carrying BPL signals

2.3 MEASUREMENT ANTENNA HEIGHT 

NTIA analyzed the electric field strength calculated from a variety of power line 

models to determine the strength of radiated emissions as a function of height. In 

addition, NTIA analyzed the difference in peak field strength over the range of simulated 

heights, and the peak field strength at 1 meter off the ground (below 30 MHz) and at 1 to 

4 meters off the ground (30 MHz and above). These results were used to assess the 

effectiveness of the measurement antenna heights specified in the measurement 

guidelines for estimating the field strength radiated from Access BPL systems. In lieu of 

measurements performed at various antenna heights, NTIA proposed the application of a 

height correction factor. The Commission’s rules for Access BPL systems adopted a 5 

dB height correction factor with a 1 meter measurement height, as an alternative to 

measuring field strength from 1 to 4 meters at or above 30 MHz.[9]

2.3.1 Height Corresponding To Peak Field Strength 

Figures 2-4 through 2-7 show the heights where the peak electric field strength 

occurred over the frequency range of 2 to 50 MHz for two of the power line topologies 

described in Section 2.2. These results were obtained at a horizontal distance of 10 

meters from the modeled power lines, and considered points all along the power line. 

The results for other power line configurations are provided in Appendix A. 

 
Figure 2-4: Height corresponding to peak electric field strength as a function of frequency

 

Figure 2-5: Height corresponding to peak electric field strength as a function of 

frequency

 
Figure 2-6: Height corresponding to peak electric field strength as a function of frequency 

 

Figure 2-7: Height corresponding to peak electric field strength as a function of frequency 

 

Figures 2-4 through 2-7 illustrate the variability of heights at which the peak 

electric field strength occurs. This variability can be seen over both frequency and power 

line topology. In those cases where the operating frequency is above 6 MHz, the peak 

field strength typically occurred at heights greater than 1 meter. Below 6 MHz, where 

the wavelengths are greater than four times the modeled power line height (12 meters), 

the increased in-phase coupling between the power line and ground will generally lead to 

the highest values of electric field at or near ground level. 
2.3.2 Peak Electric Field Strength at the Compliance Measurement 

Heights 

Although the peak field strength may occur at any height, the rules for Access 

BPL systems specify measurement heights of 1 meter below 30 MHz, and 1 to 4 meters 

at or above 30 MHz.[10] Figures 2-8 through 2-17 show the 80th percentile of peak 

electric field strength values along the power lines and over the range of simulated 

heights, relative to the peak field strength seen at the Part 15 compliance measurement 

height.[11] As previously stated in Section 2.2, the power line simulations computed 

electric field strength values at heights of 1 to 20 meters in one meter increments. The 

80th percentile values eliminate the localized peaks that are unlikely to be encountered by 

a radio receiver randomly located in close proximity to an Access BPL power line.[12]

 

Figure 2-8: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 

 

 
Figure 2-9: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 

 

 

 

Figure 2-10: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 
Figure 2-11: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 

 

 

 

Figure 2-12: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 
 

Figure 2-13: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 

 

 

Figure 2-14: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 
 

Figure 2-15: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

 

 

 

Figure 2-16: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

 
Figure 2-17: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

 

 As can be seen in Figures 2-8 through 2-17, and in Appendix A, the Part 15 

measurement heights underestimated the 80th percentile of peak electric field strength for 

the various power line models by no more than 1 dB. The use of these measurement 

heights is expected to result in reasonable estimates of peak field strength at the most 

locations surrounding overhead Access BPL power lines. 

2.3.3 Antenna Measurement Height Correction Factor above 30 MHz 

Above 30 MHz, the option to perform compliance measurements at a 1 meter 

measurement height coupled with a 5 dB height correction factor provides a much 

simpler measurement approach than to perform measurements over the specified 1 to 4 

meter range of measurement heights. Figures 2-18 through 2-23 illustrate the difference 

between the overall peak field strength (80th percentile values), which could occur at any 

height, relative to the peak field strength at the specified measurement height(s) for two 

of the simulated power line configurations. These figures show two cases: use of the 

specified 1 to 4 meter measurement height, and use of the optional 1 meter measurement 

height. The NEC simulation data were scaled to the peak levels seen in either the 

horizontal or vertical polarizations at the FCC-specified compliance measurement 

locations for the 1 meter and 1 to 4 meter height cases.[13] 

 

The results for other power line configurations modeled by NTIA are provided in 

Appendix A. 
2-18: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

 

 

2-19: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
2-20: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

 

 

 

2-21: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

 
2-22: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

 

 

 

 

2-23: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

 
NTIA’s simulation results shown here and in Appendix A indicate that scaling the 

field strength data to meet the Part 15 limits using a 1 meter antenna height tends to 

underestimate the peak field strength at any height by anywhere from 2.5 to 7.5 dB. The 

optional use of a 1 meter measurement height, with the corresponding 5 dB height 

correction factor, would result in limiting peak field strength to levels that would likely 

be seen if the measurements were performed at the specified 1 to 4 meter height above 30 

MHz. 

2.4 MEASUREMENT DISTANCE ALONG THE POWER LINE 

 As noted in NTIA’s Phase 1 Study, compliance measurement testing 

commissioned by BPL equipment vendors and service providers has generally focused on 

radiated emissions measured on radials from the BPL device under test. However, FCC 

rules state that Part 15 devices and all attached wiring should be considered when 

measuring radiated emissions.[14] In the Commission’s BPL Report and Order, the 

measurement guidelines specify the measurement locations along the power line away 

from a BPL device.[15] In this section, NTIA provides its simulation results from 

evaluating the field strength along the length of the power line and comparing this to the 

field strength levels at the prescribed measurement locations. 

NTIA evaluated the field strength along the length of the power line in 1 meter 

increments for six simulated power line configurations described in Section 2.2. These 

calculations were performed over the frequency range of 2 to 28 MHz. Figures 2-24 

through 2-31 show the electric field strength levels along the power line for a subset of 

the cases considered. Each figure includes an electric field strength level that 

corresponds to the Part 15 radiated emissions limit, when extrapolated from a horizontal 

distance of 30 meters to the horizontal measurement distance of 10 meters, and assuming 

a power line height of 12 meters.[16] In addition, these figures show the Part 15 

compliance measurement points specified in the measurement guidelines for overhead 

Access BPL systems. The peak value of electric field strength at these measurement 

points was used to scale the simulated signal source level so that the power line model 

satisfies the Part 15 limit based on the compliance measurement procedure. The 

emissions limit is extrapolated to the 10 meter measurement distance using the slant 

range distance between the simulated power line and the simulated measurement antenna 

at a height of 1 meter. Electric field strength values were determined from NEC 

magnetic field strength simulations of the power line models using the methodology 

described in Section 2.2. Results for other power line configurations are provided in 

Appendix B. 

 
Figure 2-24: Vertical electric field strength along tri36n power line model at 2 MHz

Figure 2-25: Vertical electric field strength along ver26n power line model at 2 MHz
Figure 2-26: Vertical electric field strength along tri36n power line model at 10 MHz

Figure 2-27: Vertical electric field strength along ver26n power line model at 10 MHz
Figure 2-28: Vertical electric field strength along tri36n power line model at 18 MHz

Figure 2-29: Vertical electric field strength along ver26n power line model at 18 MHz
Figure 2-30: Vertical electric field strength along tri36n power line model at 26 MHz

Figure 2-31: Vertical electric field strength along ver26n power line model at 26 MHz

The figures presented here, and those presented in Appendix B, reveal that there 

are some cases where the peak field strength may be underestimated by up to 5 dB. 

These cases generally occur at frequencies at or below 10 MHz. Where the results show 

occurrences of stronger field strength levels than the peak field strength levels seen at the 

Part 15 measurement locations specified for Access BPL systems, these occurrences are 
spatially limited along the length of the power line. Based on the power line simulations 

considered in this analysis, the emissions from Access BPL devices can be characterized 

for demonstrating compliance with the Part 15 limits using a limited number of 

measurement points, as specified in the Commission's measurement guidelines. 

2.5 MEASUREMENT DISTANCE EXTRAPOLATION 

The distance extrapolation rules for Part 15 devices define a 40 dB per decade of 

distance roll-off factor from the equipment under test (EUT) for frequencies below 30 

MHz, and a 20 dB per decade distance extrapolation factor above 30 MHz.[17] Distance 

from the EUT is described as the horizontal distance projected on the ground. NTIA’s 

measurements of Access BPL systems, documented in its Phase 1 Study, shows that the 

roll-off of radiated emissions with increasing distance from the overhead MV power lines 

occurs at a slower rate than the distance extrapolation factors specified above.[18]

 

In the BPL Report and Order, the Commission modified the measurement 

guidelines as they apply to distance extrapolation for Access BPL systems on overhead 

MV power lines by replacing the horizontal distance between the Access BPL power 

lines and the measurement antenna with the slant range distance between them.[19] Prior 

to adoption of the measurement guidelines, NTIA analyzed the use of slant range distance 

to compare the Part 15 limits, extrapolated to other measurement distances, with the 

expected field strength decay of a variety of modeled power line structures. NTIA found 

that this modification to the rules for distance extrapolation resulted in good agreement 

between the extrapolated field strength limit and the rate in which field strength decays 

from the overhead MV power line.[20] 

2.5.1 New Approach for Distance Extrapolation 

When it is necessary to make field strength measurements for overhead Access 

BPL systems at distances other than the specified Part 15 measurement distance, the field 

strength measurements are extrapolated to the Part 15 measurement distance as described 

in Equations 2-2 and 2-3 below. Figure 2-32 illustrates the concept of distance 

extrapolation using the slant path distance between the antenna and the BPL power line. 

 

 (Equation 2-2) 

where:

dslant is the slant path distance, in meters; 

 dh is the horizontal distance, in meters; 

hpwr_line is the height of the power line wiring carrying BPL signals, 

in meters; and 

hant is the measurement antenna height, in meters. 
 (Equation 2-3) 

where: 

N is distance extrapolation factor: 40 for frequencies < 30 MHz, or 20 for 

frequencies ≥ 30 MHz; 

dlimit is the horizontal measurement distance corresponding to the Part 15 

emissions limits: 30 meters, for frequencies < 30 MHz, or 10 meters, for 

frequencies ≥ 30 MHz; 

dslant is the slant path distance, in meters; 

Emeas is the measured electric field strength at a horizontal distance, dh, in 

dBV/m; and 

Eextrap is the electric field strength value after applying the distance extrapolation 

factor, in dBV/m. 

 

Figure 2-32: Slant path distance used for distance extrapolation of measurement limits

 

Table 2-2 shows the emissions levels at a measurement distance of 10 meters that 

satisfy the Part 15 limits for the distance extrapolation methodology based on horizontal 

distance and the slant-range methodology adopted in the BPL Report and Order. Figures 

2-33 and 2-34 illustrate the electric field strength levels relative to the measurement 

distance for both distance extrapolation techniques.[21]

 

 

 

Table 2-2: An example of Access BPL emissions levels that meet Part 15 limits when 

extrapolated to a 10 meter measurement distance using horizontal and slant range extrapolation

Measurement Location
 Assumed power line height 12 meters 

 Measurement height 1 meters 

 Measurement distance 10 meters 

Part 15 Limit & Distance Extrapolation

 < 30 MHz limit 29.5 dBμV/m 30 meters 

 ≥ 30 MHz limit (Class A) 39.1 dBμV/m 10 meters 

 Extrapolation < 30 MHz 40 dB/decade of distance 

 Extrapolation ≥ 30 MHz (Class A) 20 dB/decade of distance 

Extrapolated levels @ 10 m under 47 C.F.R. § 15.31(f)(1)-(2)

 < 30 MHz limit 48.58 dBμV/m 

 ≥ 30 MHz limit (Class A) 39.10 dBμV/m 

Extrapolated levels @ 10 m using slant-range distance specified for BPL devices

 < 30 MHz limit 41.70 dBμV/m 

 ≥ 30 MHz limit (Class A) 35.66 dBμV/m 

 

 

Figure 2-33: Extrapolated field strength levels meeting Part 15 emissions limits based on horizontal 

distance to a device under test, in accordance with 47 C.F.R. § 15.31(f)(1)-(2)

 
Figure 2-34: Extrapolated field strength levels meeting Part 15 emissions limits based on slant-range 

distance to the BPL power line

 

2.5.2 Calculated Electric Field Strength Decay for Distance Extrapolation 

NTIA evaluated the field strength decay relative to the distance characteristics of 

the various power line models to evaluate the Commission’s slant-range distance 

extrapolation methodology. The signal source for each power line model was scaled such 

that the radiated field strength met the Part 15 emission limits extrapolated to the 10 

meter measurement distance for the specified measurement points along the length of the 

power line. Figures 2-35 through 2-39 show the electric field strength of the modeled 

power lines and the extrapolated field strength levels meeting the Part 15 emissions limit 

for distances out to 30 meters from the power line for a subset of frequencies modeled 

below 30 MHz. Additional results are provided in Appendix C. 

 
Figure 2-35: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 2 MHz

 

Figure 2-36: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 8 MHz
Figure 2-37: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 14 MHz

 
Figure 2-38: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 20 MHz

Figure 2-39: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 26 MHz
The simulation results in the 4 to 8 MHz frequency range showed that some of the 

power line models exhibited slower rates of field strength decay with distance than would 

be expected by the distance extrapolation rate in the Part 15 rules for Access BPL 

systems. This difference in the roll-off of field strength is as much as 6 dB less than the 

distance extrapolation rate. 

 

At or above 10 MHz, the simulation results show good agreement between the 

rate that field strength decays and the distance extrapolation rate in the Part 15 rules, 

when slant path distance to the Access BPL device and power lines is used. The effect of 

the combination of direct and ground reflected rays at the simulated distances becomes 

more pronounced at frequencies above 14 MHz. 

2.6 USE OF LOOP ANTENNA BELOW 30 MHz 

Below 30 MHz, electric field strength is determined by measurement of the peak 

magnetic field in the horizontal plane using a loop antenna situated 1 meter above the 

ground. These measurements, conducted at a measurement distance of 10 meters from 

the power line, fall well within the near field region for many overhead MV power lines. 

To assess the validity of making measurements using the loop antenna below 30 MHz, 

NTIA evaluated the ratio of the peak vertical electric field to the peak magnitude of the 

horizontal magnetic field given by Equation 2-4 below: 

 (Equation 2-4) 

where η is the wave impedance, in Ω; 

Ez is the vertically polarized electric field strength in μV/m; and 

Hx, Hy are the x- and y-components of the horizontally polarized 

magnetic 

field strength in μA/m. 

 

The value of η is nominally 377 Ω in the far field. The magnetic and electric field 

strength data were calculated at a distance of 10 meters from the various NEC power line 

models at a height of 1 meter. The peak vertical electric field was calculated for the 

entire length of the modeled power lines, in one-meter steps. The magnitude of the 

horizontal magnetic field was calculated as shown in the denominator of Equation 2-4 

and its peak value along the length of the power line was determined. The ratio of these 

two values (η) was then computed. Figure 2-40 illustrates the values of η determined for 

a variety of NEC power line models for the frequency range of 2 to 28 MHz. The 

calculated values of η tend to vary from approximately 200 to 400 Ω. 
Figure 2-40: Ratio of peak electric to peak magnetic field strength at 10 meters from the power line

2.7 MEASUREMENT ANTENNA POLARIZATION 

The Commission’s measurement guidelines for Access BPL systems specify 

measurement with a loop antenna below 30 MHz, with the plane of the loop antenna 

oriented vertically at a height of 1 meter. The loop antenna is to be rotated 180° about its 

vertical axis to identify the maximum field strength. For frequencies above 30 MHz, the 

Commission specified measurements in both the vertical and horizontal polarizations 

using an electric field sensing antenna. The measurements at or above 30 MHz are made 

at antenna heights of 1 to 4 meters. 

 

A vertically oriented loop antenna measures the horizontal magnetic field. This 

corresponds to the vertical component of the electric field. By rotating the antenna about 

its vertical axis, the peak horizontal magnetic field, and thus the peak vertical electric 

field, can be measured. This is ideally the case in the far field region where the electric 

and magnetic fields are orthogonal and their values differ by the wave impedance, 377 Ω

(a reasonable assumption in the near field), as shown in Section 2.6. 

 

Although the measurement guidelines specify that field strength measurements 

should address the horizontal magnetic field (vertical electric field) below 30 MHz, 

NTIA calculated both the horizontal and vertical polarizations of field strength from a 

number of NEC power line models. The calculations were performed from 2 to 30 MHz, 

in 2 MHz increments. The resulting field strength values were used to identify which 

electric field polarization corresponds to the overall peak at the 10 meter measurement 
distance for each power line model. The vertical electric field polarization was 

consistently the strongest for the frequencies simulated below 30 MHz. 

2.8 GUIDELINES FOR CHOOSING REPRESENTATIVE 

 SYSTEMS 

The Commission’s measurement guidelines specify in-situ testing of three 

representative overhead, and three underground, BPL installations that include all Access 

BPL electronic devices such as couplers, injectors, extractors, repeaters, boosters and 

concentrators.[22] NTIA has shown in its field tests and NEC modeling of BPL power 

lines that, in addition to the BPL devices themselves, certain typical features of a MV 

power line give rise to the strongest levels of radiated emissions. These features include 

distribution transformers, risers connecting overhead and underground distribution 

circuits, distribution line endpoints and sharp direction changes.[23]

 

Other features to consider when picking representative sites for in-situ testing 

include power lines with asymmetrical features, stacked 3-phase conductors, transitions 

between three phases and one or two phases, and, where appropriate for the BPL 

equipment involved, multiple co-located BPL devices. Figures 2-41 through 2-45 

provide examples of these characteristics. 

Figure 2-41: Offset 3-phase power line conductors
Figure 2-42: Offset 2-phase power line conductors

 

 

Figure 2-43: Stacked 3-phase power line conductors
Figure 2-44: Transition from 3-phase to 2-phase conductors

 

Figure 2-45: Multiple BPL devices located on the same utility pole
2.9 SUMMARY 

The FCC’s BPL Report and Order specified the rules and measurement guidelines 

for Access BPL systems. These rules and measurement guidelines were applied in the 

analyses described in this section. 

 

The results from NEC simulations of a number of power line structures indicate 

that the peak field strength seen in close proximity to a BPL energized overhead power 

line will occur at various heights, and often near the height of the power line. NTIA 

further analyzed the peak field strength at the specified measurement heights and found 

that use of the Commission’s measurement guidelines effectively estimated the 80th

percentile values of peak field strength at any height. As noted earlier, the 80th percentile 

values eliminate the localized peaks that are unlikely to be encountered by a radio 

receiver randomly located in close proximity to an Access BPL power line. 

 

The Commission’s measurement guidelines allow field strength measurements on 

overhead Access BPL power lines operating in the Very High Frequency (VHF) band to 

optionally be performed at a 1 meter height combined with application of a 5 dB height 

correction factor. This simplification of the measurement procedure substantially reduces 

the number of measurements to be performed. Results from NTIA’s NEC simulations 

show that measurements at a 1 meter height tend to underestimate by anywhere from 2.5 

to 7.5 dB the peak field strength that would be seen using a measurement height in the 1 

to 4 meter range. The use of a 5 dB height correction factor improves the field strength 

estimate at the 1 meter measurement height to a reasonable level while greatly reducing 

the number of measurements taken. 

 

The BPL Report and Order specifies measurement at a limited number of 

locations along the power line. When the electric field strength was scaled to be within 

the Part 15 limits using the Access BPL measurement guidelines, NTIA’s NEC 

simulation results indicated that the percent of measurement points where the field 

strength exceeded the Part 15 limits was small. 

 

NTIA evaluated the Commission’s modification of the distance extrapolation 

rules, which replaced the use of the horizontal distance between the BPL device and the 

measurement antenna with the slant range distance between them. NTIA’s NEC 

simulations in the 4 to 8 MHz frequency range exhibited somewhat slower rates of field 

strength decay with distance than would be expected by the distance extrapolation rate in 

the Part 15 rules for Access BPL systems. This difference was up to 6 dB less than the 

distance extrapolation rate. At or above 10 MHz, the simulation results show good 

agreement between the rate that field strength decays and the Part 15 distance 

extrapolation rate using the slant range distance to the Access BPL device and power 

lines. As noted earlier, the effect of the combination of ground and reflected rays at the 

simulated distances becomes more pronounced at frequencies above 14 MHz. 

 

The use of slant range distance with the extrapolation rates (40 dB per decade of 

slant range distance below 30 MHz, and 20 dB per decade of slant range distance at or 

above 30 MHz) defined in the rules most accurately estimates electric field strength when 
extrapolation is performed in close proximity to the BPL device and associated power 

lines. At great distances, the accuracy of this approach diminishes. At larger distances 

between the BPL device and measurement antenna, the slant range distance and the 

horizontal distance are approximately the same, and the extrapolation rate effectively 

becomes the same as if the horizontal distance was used. The Commission’s rules state 

that measurements shall not be performed at distances greater than the specified 

measurement distance, or less, unless it is impractical to do so.[24] 

Below 30 MHz, the electric field strength is determined by measuring the peak 

magnetic field strength in the horizontal plane using a loop antenna situated 1 meter 

above the ground, and applying a magnetic to electric field conversion factor of 377 Ω. 

These measurements, conducted at a distance of 10 meters from the BPL device and 

associated power lines, fall well within the near field region for many overhead MV 

power lines. NTIA evaluated the relationship between the magnetic and electric fields at 

10 meters using a number of NEC power line models and determined that use of the loop 

antenna with this conversion factor provides a reasonable approximation at this distance. 

NTIA simulations investigating the field strength of both the vertical and horizontal 

polarizations showed that below 30 MHz, the vertical electric field (horizontal magnetic 

field) corresponds to the peak field strength when measured at 10 meters from the power 

line. This is consistent with the polarization specified by the Commission’s measurement 

guidelines for Access BPL systems. 

 

In Section 2.8, NTIA provided recommendations for choosing representative 

overhead MV Access BPL locations for in-situ testing. NTIA field tests and NEC 

modeling of BPL power lines identified that, in addition to the BPL devices themselves, 

many features of MV power lines give rise to the strongest levels of radiated emissions. 

NTIA suggests that a variety of these features should exist in power lines chosen as 

representative sites for compliance measurement testing. 

 

SECTION 3 

SPECIAL PROVISIONS FOR PREVENTION OF INTERFERENCE 

FROM BPL SYSTEMS 

3.1 INTRODUCTION 

NTIA’s Phase 1 Study identified frequency bands in the 1.7 to 80 MHz frequency 

range for which radio operations have been specially protected in the FCC’s rules or 

International Telecommunication Union (ITU) Radio Regulations.[25] NTIA’s comments 

on the BPL NPRM recommended that the FCC adopt special mechanisms for preventing 

interference in addition to the baseline protection afforded by field strength limits, 

prohibition of harmful interference from BPL systems, and compliance measurement 

provisions.[26] The Commission adopted rules in its BPL Report and Order that 

delineated frequencies and areas in which these special provisions would apply.[27]

 

Aeronautical and maritime safety radiocommunications receivers, as well as radar 

and radioastronomy receivers operating at frequencies below 80 MHz may experience 

harmful interference from in-band emissions from relatively distant Access BPL 

systems. The Commission’s BPL rules reduce the probability of BPL interference to 

such receivers by defining excluded frequency bands, exclusion zones, and consultation 

areas around the most sensitive federal radiocommunications facilities.[28] Within these 

areas, BPL systems are either prohibited outright or may be restricted from transmitting 

in specific frequency bands by mutual agreement between BPL service providers and 

federal radio operators. NTIA analyzed BPL emissions in these bands and confirmed the 

effectiveness of the protection radii adopted in these rules. 

 

Excluded frequency bands (discussed in Section 3.4.1) place the greatest 

constraints on BPL deployment, including limitations on the flexibility for Access BPL 

systems to avoid other locally-used radio frequencies. Thus, frequency bands used for 

safety communications where co-channel emissions from numerous BPL devices may be 

received via line-of-sight and/or ionospheric interfering signal paths make up the 

excluded bands. 

 

Exclusion zones (discussed in Section 3.4.2) are applied to protect reception at 

known receiver locations where safety communications must operate with weak desired 

signals and cooperation between BPL service providers and federal radio operators is 

unlikely to result in lesser constraints on BPL. Likewise, exclusion zones are applied 

around sensitive radio astronomy sites, which generally are located in remote, lightly 

populated areas (i.e., little or no actual constraint on Access BPL market penetration). 

 

Consultation areas (discussed in Section 3.4.3) are specified for receivers at 

known locations that must operate with very weak desired signals and where harmful 

interference must be prevented with a relatively high degree of certainty (rather than 

eliminated after discovery). Actual radio operating frequencies and other technical or 
operational details (e.g., manufacturer and type of BPL equipment, location of BPL 

service) should be considered during consultations. 

 

Sections 3.4 and 3.5 provide the technical basis for these exclusion zone and 

consultation area distances. The underlying interference predictions demonstrate that 

Access BPL systems located beyond these distances would: 

 

• be unlikely to cause substantial interference to receivers that are intended to be 

protected by these provisions, even given worst-case-oriented BPL deployment 

configurations; and 

 

• present a very low probability of endangerment or actual harmful interference to 

safety communications and non-safety communications, respectively. 

 

3.1.1 Background 

NTIA analyzed the BPL emissions levels that might be expected from MV 

overhead and underground power lines to determine the minimum radii of exclusion 

zones and consultation areas needed to meet the protection criteria for critical federal 

communication, radar and radioastronomy receivers. MV overhead lines are attached to 

utility poles at heights that typically range from 8 – 12 meters above ground. BPL 

signals are typically injected on one or more of the phase conductors at a utility pole. 

Underground power lines radiate the strongest emissions from above-ground segments, 

including mainly: pad mounted transformer enclosures; vertical risers where the power 

line emerges from underground and is routed up the side of a pole inside a metal, 

protective U-channel for connection with overhead power lines; and short line segments 

emerging from the ground and running through metal pipes for connections to the users’ 

premises (low-voltage) or power substation (MV). The BPL signal typically is injected 

on the underground segment at one of the transformer pads. 

 

NTIA’s initial analyses of these distances employed a 5 dB height correction 

factor to account for stronger predicted levels of BPL emissions from the power line at 

heights other than that used for compliance measurements. In its Phase 1 Study and in 

the Technical Appendix to its Comments on the BPL NPRM, NTIA showed that the peak 

field strength typically occurs at heights greater than the 1 meter measurement height 

used for compliance testing, and is often found at or near the height of the power line.[29]

 In the BPL Report and Order, the Commission adopted NTIA’s recommended height 

correction factor, which may be optionally applied above 30 MHz when coupled with an 

antenna measurement height of 1 meter. The Commission indicated that BPL emissions 

above 30 MHz may be measured with an antenna height ranging from 1 to 4 meters. 

NTIA’s revised analysis no longer assumes the 5 dB correction (reduction of BPL 

emissions) factor in calculating the size of these protection areas. 

 

NTIA’s earlier analysis also assumed that the receiver antenna gain for fixed/or 

mobile-base stations was 0 dBi in the direction of the power line carrying BPL signals. 
This assumption was felt to be valid for many high-gain antennas operating in the near 

field of a BPL power line. However, NTIA conducted NEC simulations with a 

representative high-gain antenna (14 dBi maximum) to validate this assumption and 

found that the receiver antenna gain in the direction of the BPL power line may be as 

much as 5 dBi, depending on frequency. In response to these results, NTIA has revised 

its analysis to account for receiver antenna gain toward the power line. 

 

Theory and limited NTIA measurements show that Access BPL using 

underground power lines poses very small, relatively localized interference risks, 

radiating potentially significant emissions only from above-ground segments. Each 

phase wire of MV underground power lines has a ground wire that is loosely, coaxially 

braided or wound around the insulation of the phase conductor. This ground wire 

suppresses radiation. Also, soil is a high-loss propagation medium in the 1.7-80 MHz 

frequency range. Above-ground segments of underground power line systems act as 

point radiators similar to other Part 15 devices. 

 

The calculations to determine the exclusion zones and consultation radii consider 

only the effect of local co-frequency BPL devices on radio receivers over line-of-sight 

and diffracted interfering signal paths. Ionospheric propagation of distant BPL signals 

and ionospheric backscatter from local BPL devices are not considered in this section of 

the report. 

3.2 POTENTIAL VICTIM RECEIVERS 

 The NTIA Phase 1 Study included a characterization of Federal Government 

spectrum usage in the 1.7 to 80 MHz band, representative systems, and typical system 

parameters.[30] A number of these radiocommunication systems are considered 

particularly sensitive as they pertain to aeronautical and maritime safety-of-life services. 

Other federal systems that warrant protection include over-the-horizon radars and 

radioastronomy observatories. These potential victims of in-band emissions from Access 

BPL systems are described in the following sections. 

 

3.2.1 Communications Receivers 

 The United States Coast Guard operates high frequency (HF) systems for 

communications between shore stations and ships, and from ship-to-ship. These systems 

support command and control communications with cutters, aircraft, and shore facilities 

for various purposes including: off shore search and rescue; drug interdiction; 

enforcement of laws and treaties; and Arctic and Antarctic operations. The Coast Guard 

relies on the HF band for services such as distress and safety communications, broadcast 

of maritime safety information, emergency medical assistance communications, 

broadcast of weather observation reports, and receipt of vessel position reports for safety 

purposes. In addition, the Coast Guard has an HF network that ties its major bases 

together throughout the continental United States (CONUS), Alaska, Hawaii, Puerto 
Rico, the U.S. Virgin Islands, and the trust territories of the Pacific Ocean. The typical 

technical characteristics for these maritime mobile base stations are described in Table 3-

1. 

 

Table 3-1: Typical technical characteristics of Maritime Mobile base stations in the 1.7-30 MHz Band

Bandwidth 

(kHz)

Ant. Gain 

(dBi)

Ant. 

Height (Ft)

Ant. Type/ 

Polarization Modulations

2.8 0-2 Not 

available

Whip, 

Cone/V 

Single sideband-suppressed carrier, single 

channel, analog, telephony 

 

The United States Customs and Border Protection Customs Over the Horizon 

Enforcement Network (COTHEN) provides communications support for more than 235 

aircraft, numerous maritime interdiction vessels, several command offices, and numerous 

allied agencies including the United States Coast Guard, Drug Enforcement 

Administration, Border Patrol, Army, Navy, and Joint Interagency Task Forces. The 

typical technical characteristics for the COTHEN fixed base stations are described in 

Table 3-2. 

 

Table 3-2: Typical technical characteristics of COTHEN base stations in the 1.7-80 MHz Band

Bandwidth

(kHz)

Ant. Gain

(dBi)

Ant. 

Height

(Ft)

Ant. Type/

Polarization Modulations

2.8 0 30-100 Whip/V& H Analog, single channel, suppressed carrier, 

telephony 

 

 The aeronautical mobile service is subdivided into two distinct radio services; 

namely, aeronautical mobile route (R) and aeronautical mobile off-route (OR) services. 

By definition, the aeronautical mobile (R) service is reserved for communications relating 

to safety and regularity of flight, primarily along national or international civil air routes; 

while the aeronautical mobile (OR) service is intended for other communications, 

including those relating to flight coordination, primarily outside national or international 

civil air routes.[31]  

 Table 3-3 shows typical technical characteristics of federal systems in the 

aeronautical mobile (R) service. Table 3-4 shows typical technical characteristics of 

federal aeronautical mobile (OR) service systems in the HF band. 

 

Table 3-3: Typical technical characteristics of Aeronautical Mobile (R) base stations 

(1.7-30 MHz Band)

Bandwidth 

(kHz)

Ant. Gain 

(dBi)

Ant. Height 

(Ft)

Ant. Type/

Polarization Modulations

2.8 0-3 Not 

available Various /V Analog, single channel, suppressed carrier, telephony

 

Table 3-4: Typical technical characteristics of Aeronautical Mobile (OR) base stations 

(1.7-30 MHz Band)

Bandwidth 

(kHz)

Ant. Gain 

(dBi)

Ant. Height 

(Ft)

Ant. Type/

Polarization Modulations
3.5 0 6-32 Whip/V Analog and digital, single channel, reduced or 

suppressed carrier, telephony and data

 

The size of the exclusion zones and consultation areas recommended by NTIA for 

base stations associated with the land mobile, maritime mobile, aeronautical mobile (R) 

and (OR) services result from analyzing the distances at which radiated emissions from 

an Access BPL source raises the noise floor by a certain amount.[32] The exclusion zone 

and consultation area radii were chosen to be the distance beyond which the probability 

that a communications receiver experiences a 1 dB increase in noise floor is negligible. 

3.2.2 Radar Receivers 

HF band over-the-horizon (OTH) radar systems are employed by the Department 

of Defense. The OTH radars use sky wave propagation to detect targets at long ranges 

from the radar transmitter site. The target return is a result of the backscatter signal 

traversing the path to the ionosphere and back to the original transmitter site (primary 

radar) or an alternative site (secondary site). OTH-HF radars are capable of detecting 

targets at distances beyond the horizon and therefore, targets located well beyond the 

range of the conventional microwave radar. This increased range is possible due to the 

ability of the HF signals to propagate well beyond the line-of-sight either by ground wave 

diffraction around the curvature of the Earth or by sky wave. The basic technical 

characteristics of the OTH radar receiver are shown in Table 3-5. 

 

 

 

Table 3-5: Technical characteristics of the OTH radar receiver (1.7-30 MHz Band)

Bandwidth 

(kHz)

Ant. Gain 

(dBi)

Ant. Height 

(Ft)

Ant. Type/

Polarization Modulations

4.2-100 9-36 * Not available Phased Array/ 

Vertical

FM/CW or angle-modulated, single 

channel, with analog or digital signals. *

 The 9 dBi and 36 dBi antenna gains are measured at 5 MHz to 28 MHz, respectively.

The protection requirement used to develop the exclusion zone for OTH radar 

receivers in the 1.7 to 30 MHz band is a spectral power flux density (PFD) threshold of 

-258 dBW/m2

-Hz.[33] This analysis assumes that the interfering BPL signal is received 

through a 0 dBi side lobe of the radar antenna. 

3.2.3 Radioastronomy Receivers 

Radio astronomical measurements are made from the Earth’s surface from 2 MHz 

to beyond 800 GHz. The sensitivity of radio astronomy receivers greatly exceeds the 

sensitivity of typical communications and radar equipment. The sensitivity is defined by 

the smallest power level change, ΔP, at the receiver input that can be detected and 

measured. The interfering signal threshold levels are defined as the interfering signal 

level which introduces an error of 10 percent in the measurement of ΔP. 

The protection criterion applicable for terrestrial interference sources is based on 

reception of an interfering signal through 0 dBi side lobes of a radioastronomy antenna. 
The International Telecommunication Union Radiocommunications Sector (ITU-R) 

protection level for radioastronomy is a spectral PFD of -258 dBW/m2

-Hz in the 73.0-

74.6 MHz frequency band.[34] This level is assumed for the radioastronomy exclusion 

zone radii analysis.

3.3 POTENTIAL SOURCES OF INTERFERENCE 

Using the NEC software, NTIA modeled the field strength of MV overhead and 

underground BPL power lines for this analysis. A description of these models follows 

below. 

3.3.1 Overhead Power Line Model 

NTIA modeled an overhead BPL power line as three horizontal parallel copper 

wires, each 340 meters long and 8.5 meters (27.9 feet) above ground having average 

characteristics (conductivity σ = .005 S/m, relative permittivity εr = 15). Each wire had a 

diameter of 1 centimeter (approximating American Wire Gauge (AWG) gauge 4/0) and 

the wires were separated in the horizontal plane by 0.60 meter. The feed point was at the 

center of one of the outside wires, which ran parallel to the x axis (y = 0). The equivalent 

of a BPL coupler was placed on the center segment of the wire and was modeled as a 

voltage source of 1 volt in series with a 150 Ω resistor that represented the source 

impedance. The other two phase wires ran parallel to the x axis at y = 0.6 and y = 1.2 

meters. All wires were connected at the ends to one another through 50 Ω impedances to 

model the loads. The overhead power line was modeled at a number of discrete 

frequencies ranging from 4 MHz to 74 MHz. 

3.3.2 Underground Power Line Model 

NTIA created a NEC model of an Underground Residential Distribution (URD) 

cable and a shielded, pad-mounted transformer for the radioastronomy (Section 3.4.3) 

and aggregation (Section 5) analyses. The modeled cable consisted of a center copper 

conductor 1 centimeter in diameter, surrounded by simulated cross-linked polyethylene 

insulation (using NEC’s Insulated Wire feature) having a thickness of 6 millimeters. 

Around the outside of the insulation were three 12 AWG multi-grounded neutral copper 

wires. 

 

The URD cable in the NEC model spanned 340 meters (+/- 170 meters along the 

x-axis), 1 meter below ground level. Near the origin, the cable was routed up to ground 

level, breaking the surface inside a wire-grid rectangular structure one meter on a side 

and one-half meter high. This structure represented the pad-mounted transformer casing, 

and was given steel conductivity. The wires composing the transformer casing were 4 

millimeters thick (Figure 3-1). 

 

Inside the transformer casing, only the center conductor of the URD cable continued 

above ground. The simulated BPL device was placed on this short loop of wire, 0.2 

meters off the ground. 
Figure 3-1: Representation of a NEC model of an underground BPL power line and transformer pad

 

3.3.3 Part 15 Scaling of Power Line Models 

NTIA computed electric field strength values for these NEC power line models 

using the measurement guidelines for Access BPL systems. Below 30 MHz, the 

measurement guidelines specify measurement of magnetic field with a loop antenna 

rotated about its vertical axis (horizontal magnetic field) at a height of 1 meter. 

Conversion to electric field strength resulted from application of Equation 2-1 (page 2-2). 

 

Below 30 MHz, the FCC Part 15 radiated emissions limit is specified as 30 μV/m 

at 30 meters horizontal distance.[35] To convert the limit to the 10 meter distance 

specified in the measurement guidelines for Access BPL systems, the slant range between 

an overhead power line and the measurement point must be used in conjunction with a 40 

log correction factor. Application of Equations 2-2 (page 2-22) and 2-3 (page 2-23) with 

a modeled overhead power line height of 8.5 meters and measurement height of one 

meter, the slant range adjustment to the electric field strength limit results in an 

extrapolated value of the Part 15 limit at 10 meters as shown below. The peak value of 

Ev from the specified measurement locations along the power line was scaled to achieve 

the value of E10m shown below. The specified measurement locations were at points 1⁄4, 

1⁄2, 3⁄4, and 1 wavelength down the line from the BPL source. 

 

 
Above 30 MHz, the Part 15 Class A emission limit of 90 μV/m, at a distance of 

10 meters, applies and the measurement height ranges from 1 to 4 meters. The peak 

value of the horizontal and vertical electric field strength from the specified measurement 

locations along the overhead power line and at the specified measurement heights was 

scaled to the 90 μV/m emissions limit.[36]

 

The underground BPL system was analyzed at 74 MHz in this study; therefore, 

the Class A emission limit of 90 μV/m, 10 meter measurement distance, and the 1 to 4 

meter measurement heights were applied. Instead of measurement points along the 

power line, as would be the case for overhead power lines, the underground system was 

measured at 16 evenly spaced radials surrounding the BPL signal source. The peak value 

of the horizontal and vertical electric field strength from the 16 radials surrounding the 

underground BPL source and at the specified measurement heights was scaled to the 90 

μV/m emissions limit. 

 

With the Part 15 calibration completed, NTIA used NEC to calculate field 

strength values over a range of horizontal distances from the BPL device and elevation 

angles determined by the assumed receive antenna. 

3.4 ANALYTICAL APPROACH 

3.4.1 Communications Receivers 

This analysis evaluates the protection radii needed around base station receivers 

for the various federal radiocommunication systems discussed in Section 3.2. The NEC 

software tool was used to model a representative radio receiver antenna. The model was 

initially patterned as a horizontal dipole at 42.7 meters above ground with a gain of 0 dBi 

in the direction of the power line.[37] NEC models were used to calculate the electric field 

strength values at points along and away from the power line at the assumed height of the 

receiver antenna, and then translate these values into received interfering signal power 

levels. 

 

NTIA subsequently developed a second NEC model to address the typical gain in 

the direction of the power line for a high-gain receiver antenna. This high-gain antenna 

was patterned after a stacked log-periodic antenna used for aeronautical 

radiocommunications.[38] This antenna model has a maximum gain of approximately 14 

dBi for frequencies between 4 to 30 MHz, with a gain in the direction of the power line 

of up to 5 dBi. In order to model more accurately the BPL signal power seen by a 

communications receiver with a high-gain antenna, NTIA utilized NEC’s Maximum 

Coupling feature to determine the loss of power between the modeled BPL source and the 

modeled stacked log-periodic antenna receive point. 

 

The use of exclusion zones and consultation areas is intended to reduce the risk of 

harmful interference at these protected receiver sites. Their radii are determined by 

noting the distance from the modeled power line where the radiated emissions from a 

BPL source raise the noise floor (e.g., (I+N)/N) by a certain amount. The radii chosen 
were determined to be the distances beyond which the probability was negligible that a 

communications receiver would experience an increase in noise floor of 1 dB. 

 

The BPL interfering signal power “I” was determined from NEC power line 

simulations. Calculations of electric field strength for the 0 dBi receiver antenna case 

were made along the length of the modeled power line in 0.5 meter steps. These 

calculations were performed at increasing distances away from the power line at a height 

of 42.7 meters, the height of the assumed communications receiver antenna. For the 

high-gain antenna case, the field strength calculations along the power line were 

performed at 5 meter steps along the power line to reduce computation time for the 

analysis. 

 

The noise power “N” was assumed to be the median noise level for a quiet rural 

noise environment. This assumption is reasonable, as most of these protected receiver 

sites were selected because they exhibit very low background noise levels. In addition, 

personnel at these sites (where manned) actively work with local utilities to prevent or 

correct any increases in ambient noise due to power line noise sources. The noise levels 

used in this analysis are listed in Table 3-6. 

 

Table 3-6: Ambient noise level assumptions used in the communications receiver analysis[39]

Frequency Bandwidth Noise Power Level

4 MHz 2.8 kHz -135.3 dBW

10 MHz 2.8 kHz -136.7 dBW

15 MHz 2.8 kHz -144.7 dBW

20 MHz 2.8 kHz -147.9 dBW

25 MHz 2.8 kHz -150.2 dBW

30 MHz 16 kHz -144.6 dBW

40 MHz 16 kHz -147.5 dBW

 

NTIA calculated the percentage of simulation points that, at a given distance 

around the modeled power line, resulted in a 1 dB noise floor increase. These 

calculations were performed at increasing distances away from the modeled power line. 

3.4.2 Radar Receivers 

In analyzing the protection radii for radar receivers, NTIA employed the NEC 

overhead power line model described in Section 3.3.1 and the Irregular Terrain Model 

(ITM) software to calculate the basic transmission loss due to the distance separation and 

diffraction of a radio frequency (RF) signal over a spherical earth.[40] The protection 

requirement used in this analysis for radar receivers in the 1.7 to 30 MHz band is a PFD 

threshold of -258 dBW/m2

-Hz. This protection criterion assumes reception of a 

terrestrial interfering signal through a 0 dBi side lobe of a radar antenna. 

 

NTIA used NEC to calculate the peak electric field strength at horizontal 

distances of 1 to 10 kilometers from the BPL device and an elevation of 42.7 meters, the 
assumed height of the receiving antenna.[41] The electric field strength values computed 

by NEC were converted into PFD values using Equation 3-1 below: 

 

 

(Equati

on 3-1) 

where 

PFDNEC is the power flux density computed by NEC, in dBW/m2

-

Hz; 

dist is the distance separation between the BPL source and the 

radar receiver, in meters; 

E is the electric field strength, scaled to meet Part 15 limits, 

in V/m; 

BWmeas is the Part 15 measurement bandwidth, in Hz;[42] and 

nequiv is the number of equivalent-power BPL sources 

contributing to the PFD calculation. 

PFD values are calculated based on the root mean square (RMS) value of electric 

field strength; therefore, the peak electric field strength values determined by the NEC 

simulation were adjusted downward by a factor of 6 dB.[43] The analysis assumes that the 

calculated PFD is based on the equivalent of four equal-power BPL signals (nequiv = 4) 

operating at the Part 15 limit, accounting for potential aggregation of multiple cofrequency emission sources beyond the protection radius surrounding the radar antenna. 

The four simulated power lines were assumed to be oriented broadside (θ = 90o) to the 

receiving antenna. This assumption was used to provide a reasonable simplification of the 

analysis, where a widely deployed BPL system may encompass many more than four cofrequency BPL devices generating various field strength levels at or below the Part 15 

limit with a variety of distances and orientations with respect to the receiving antenna. 

 

Simulations using NEC were run to a distance of 10 km from the power line since 

NEC does not account for the diffraction losses that would be expected at greater 

distances. ITM transmission loss data was used to calculate PFD values from 10 km out 

to 50 km. The ITM results were based on use of the same ground parameters as NEC, 

and the same power line height of 8.5 meters and an assumed radar antenna height of 

42.7 meters.[44] ITM input parameters are detailed in Table 3-7. 

 

Table 3-7: ITM input parameters

Input Variable Value

Frequency[45] 25 MHz
Antenna Heights Transmitter – 8.5 m, Receiver – 42.7 m

Siting Criteria Transmitter – Random, Receiver – Very 

Careful

Terrain Irregularity 

Factor, Δh 30 m

Polarization Horizontal

Relative Permittivity 15

Ground Conductivity 0.005 S/m

Climate Continental Temperate

Surface Refractivity 301 N-units

Percent Time 90.0%

Percent Location 50.0%

Percent Confidence 50.0%

Mode of Variability Individual

 

To determine the PFD values accounting for diffraction losses that come into play 

at large distances from the power line, the transmission losses beyond 10 km calculated 

by ITM were scaled relative to the value that ITM computed at 10 km (Equation 3-2). 

Within 10 km of the power line, the adjusted PFD was the same as the PFD computed 

using NEC electric field strength directly (Equations 3-1 and 3-3a). Beyond 10 km, the 

scaled ITM loss values, at each distance, and the PFD computed at 10 km from NEC 

were used to compute the adjusted PFD 

(Equation 3-3b). 

 (Equation 3-2) 

where 

 dist is the horizontal distance from the power line, in km; 

 LossITM is the path loss at a distance, in dB; and 

 ScaledLossITM is the path loss at a distance relative to the path loss at 

 10 km from the power line, in dB. 

PFDAdjusted(dist) = PFDNEC(dist), for 0≤ dist < 10 km (Equation 3-3a) 

PFDAdjusted(dist) = PFDNEC(10 km) – ScaledLossITM(dist), for dist ≥ 10 km (Equation 3-3b) 

 

 where 

 PFDNEC is the power flux density computed by NEC, in dBW/m2

-

 Hz; and 

 PFDAdjusted is power flux density, at a distance, adjusted by the relative 

 path loss beyond 10 km, if applicable, in dBW/m2

-Hz. 

 
3.4.3 Radioastronomy Receivers 

The methodology described in Section 3.4.2 was also used to analyze protection 

area requirements for radioastronomy receivers. The peak electric field strength, 

computed at any distance, was converted into PFD values at the receiver for comparison 

to the -258 dBW/m2

-Hz interference threshold.[46] This protection criterion is applicable 

for terrestrial interference sources based on reception of the interfering signal through 0 

dBi side lobes of a radioastronomy antenna. 

 

NEC was used to calculate electric field strength values at horizontal distances of 

1 to 10 kilometers from the BPL device and at an elevation of 20 meters, the assumed 

height of the radioastronomy antenna. These field strength values were converted into 

PFD values using Equation 3-1. 

 

The calculated values of peak electric field strength were adjusted downward by a 

factor of 6 dB to approximate the RMS values required for determining PFD values. As 

in the radar receiver analysis, the calculated PFD is based on the assumption of an 

equivalent of four equal-power BPL signals (nequiv = 4), accounting for potential 

aggregation of multiple co-frequency emission sources beyond the protection radius 

surrounding the radar antenna. The four simulated power lines were assumed to be 

oriented broadside (θ = 90o) to the receiving antenna. This assumption was used to 

provide a reasonable simplification of the analysis, where a widely deployed BPL system 

may encompass many more than four co-frequency BPL devices generating various field 

strength levels at or below the Part 15 limit with a variety of distances and orientations 

with respect to the receiving antenna. 

 

As indicated above, electric field strength simulations using NEC were only run 

to a distance of 10 km from the power line, as NEC does not account for the diffraction 

losses that would be expected at greater distances. ITM transmission loss data was used 

to calculate PFD values from 10 km out to 50 km. The ITM input parameters remained 

the same as for the radar receiver case, with the exception that the radioastronomy 

receiver antenna was assumed to have a height of 20 meters and the analysis frequency 

was assumed to be 74 MHz.[47] To determine the PFD values accounting for diffraction 

losses that come into play at large distances from the power line, the transmission losses 

beyond 10 km calculated by ITM were scaled relative to the value that ITM computed at 

10 km (Equation 3-2). Within 10 km of the power line, the adjusted PFD was the same 

as the PFD computed using NEC electric field strength directly (Equations 3-1 and 3-

3a). Beyond 10 km, the scaled ITM loss values, at each distance, and the PFD computed 

at 10 km from NEC were used to compute the adjusted PFD (Equation 3-3b). 

 

For the underground BPL analysis, the ITM input parameter for the transmitter 

antenna was set to 0.2 meter.[48] This is the height at which the BPL device protrudes 

above ground in the NEC underground power line model. In addition, the transition to 

ITM-computed transmission losses was made at a distance of 1 km, the minimum 

separation distance supported by ITM. Unlike the overhead BPL case, the far field 

region for the underground BPL case is close to the BPL device because the underground 

wiring only protrudes above ground for a length on the order of 1 meter. The extent of 
the near field region for the underground case is only meters or tens of meters from the 

BPL device. 

3.5 SIMULATION RESULTS 

A summary of the simulation conditions described in Section 3.4 is provided in 

Table 3-8. The results for communications receivers based on limiting the noise floor 

increase to 1 dB are provided in Section 3.5.1. The results for limiting the PFD seen by 

radar and radioastronomy receivers to less than -258 dBW/m2-Hz are described in 

Sections 3.5.2 and 3.5.3, respectively. 

 

Table 3-8: Simulation Conditions

Power Line Models Overhead Underground

Conductors 3 horizontal 1 power / 3 neutral

Conductor Material Copper Copper

Conductor Thickness 1 cm (approx. AWG 4/0) 1 cm (approx. AWG 4/0)

Conductor insulation N/A 6 mm cross-linked 

polyethylene

Conductor spacing 0.6 m -

Length 340 m 340 m

Height above ground 8.5 m -1 m

Coupler location Center conductor, center of 

span

Power conductor, 0.2 m 

above ground

Source 1 Volt in series with 150 Ω 1 Volt

Load 50 Ω between conductors -

Shield enclosure size N/A 1 m x 1 m x 0.5 m high

Shield material N/A Steel

Shield thickness N/A 4 mm (wire grid)

Ground Conditions

Conductivity σ = 0.005 S/m

Relative permittivity εr = 15

Simulation Frequencies

Communication Receiver 4, 10, 15, 20, 25, 30, 40 MHz

OTH Radar 25 MHz

Radioastronomy 74 MHz

Number of BPL emitters (equal power, co-frequency, broadside orientation) 

Communication Receiver 1, 2

Radar / Radioastronomy 4

Receiver Antenna

Communication Receiver Low Gain High Gain

Type Horizontal dipole Stacked log-periodic

Gain towards power line 0 dBi 5 dBi

Height 42.7 m 12.5m (average)
OTH Radar

Gain towards power line 0 dBi

Height 42.7 m

Radioastronomy

Gain towards power line 0 dBi

Height 20 m

Noise Conditions Quiet Rural, as per Table 3-6

ITM Conditions

Frequency Radar – 25 MHz Radioastronomy – 74 MHz

Antenna Heights

Transmitter (Power line) Overhead Underground

Height 8.5 m 0.2 m

Receiver Radar Radioastronomy

Height 42.7 m 20 m

Siting Criteria Transmitter – Random Receiver – Very Careful

Terrain Irregularity Factor, 

Δh

30 meters

Polarization Horizontal

Relative Permittivity 15

Ground Conductivity 0.005 S/m

Climate Continental Temperate

Surface Refractivity 301 N-units

Percent Time 90.0%

Percent Location 50.0%

Percent Confidence 50.0%

Mode of Variability Individual

Interference Criteria

Communication Receiver Noise Floor Increase ((I+N)/N) = 1 dB

Radar / Radioastronomy PFD = -258 dBW/m2-Hz

 

3.5.1 Communications Receivers 

Figures 3-2 through 3-8 illustrate the percentage of points along a simulated BPL 

power line where the noise floor increase due to BPL emissions from 4 to 40 MHz 

exceeds 1 dB, in a receiver having antenna gain of 0 dBi towards the power line. These 

results are plotted relative to the horizontal distance away from the power line. Figures 

3-9 through 3-11 show the simulation results at 4, 15 and 25 MHz for a 14 dBi gain 

receiving antenna having up to 5 dBi of gain in the direction of the power line. In these 

plots, the results are shown for the case of a single Access BPL device operating at the 

Part 15 limit, and for the assumed case of two equal-power co-frequency Access BPL 

devices operating at the Part 15 limit. This latter assumption may encompass more than 

two co-frequency BPL devices generating various field strength levels below the Part 15 

limit. Figure 3-12 summarizes the minimum radii needed to limit the noise floor increase 

to 1 dB or less, assuming the presence of two equal-power co-frequency BPL devices 
operating at the Part 15 limit. The minimum radii correspond to the horizontal distances 

at which 0 percent of the data points around the simulated power line result in a 1 dB 

noise floor increase. 

 

Figure 3-12 shows that distances beyond which a 1 dB increase in noise are 

predicted to be possible increase slowly as frequency increases from 1.7 MHz to over 10 

MHz, mainly as a result of decreasing median noise power levels. Between 15 MHz and 

30 MHz, the greater radiation efficiency of the BPL power line significantly increases the 

distances where the noise floor can increase by 1 dB or more. The gain of the modeled 

high-gain antenna in the direction of the BPL power line is greatest between 15 MHz and 

30 MHz as well. 

 

Distance results for 4 MHz have been applied to establish the adopted 1 km 

exclusion zone dimension for the 2,173.5 to 2,190.5 kHz band used by coast stations.[49] 

Upward rounding of the 4 MHz distance of 895 meters to 1 km and application of that 

distance from the boundary of the coast station facility accommodates receiver antenna 

location flexibility, error tolerance in the reported antenna coordinates, and the possibility 

that other BPL power line configurations not evaluated herein may generate higher field 

strength. 

 

Among the frequencies considered, the largest distance within which a 1 dB 

increase in noise is predicted occurs at 25 MHz (distance of about 3.9 km). Upward 

rounding of this distance to 4 km would accommodate error tolerance in the reported 

antenna coordinates and the possibility that other BPL power line configurations and BPL 

signal aggregation not evaluated herein may generate higher field strength. 

 

Figure 3-2: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line
 

 

 

Figure 3-3: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line

 

 

Figure 3-4: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line
 

 

 

Figure 3-5: Protection Percentage of points exceeding a 1 dB increase in noise floor as a function of 

distance from the power line

 

 

Figure 3-6: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line
 

 

 

Figure 3-7: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line

 

 

Figure 3-8: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line
 

 

 

Figure 3-9: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line

 

Figure 3-10: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line

 

 
 

Figure 3-11: Percentage of points exceeding a 1 dB increase in noise floor as a function of distance 

from the power line

Figure 3-12: Summary of minimum protection area radii to limit noise floor increase to 1 dB or less

 
3.5.2 Radar Receivers 

The calculated PFD at a radar receiving antenna located at various horizontal 

distances from multiple overhead BPL sources is shown in Figure 3-13. The results show 

the PFD at 25 MHz due to four equal-power co-frequency overhead BPL sources, 

positioned at a height of 8.5 meters above the ground and radiating at the Part 15 limit in 

the direction of the receiving antenna at the horizontal distances plotted below. As the 

results presented in Section 3.5.1 illustrate, the modeled overhead power line radiates 

most effectively at 25 MHz, and therefore, this frequency was chosen for evaluation in 

the radar receiver analysis. 

 

Figure 3-13 shows that the maximum PFD levels begin to exceed the assumed 

threshold of -258 dBW/m2-Hz at horizontal distances of 36 km or less from the power 

line. The Commission, in its BPL Report and Order, adopted a radius of 37 km for 

consultation areas around a number of critical radar receiving facilities in the 1.7 to 30 

MHz frequency range.[50]

 

Figure 3-13: Power flux density relative to the distance from overhead BPL at 25 MHz (4 equal 

power co-frequency BPL signal sources)

3.5.3 Radioastronomy Receivers 

The PFD levels expected at a radioastronomy antenna located at various 

horizontal distances from overhead and underground BPL sources are shown in the 

figures below. These analyses assumed that there were four equal-power co-frequency 

BPL sources radiating at the Part 15 limit in the direction of the receiving antenna. 
 

For the overhead BPL power line case, the BPL sources were assumed to be 

positioned at a height of 8.5 meters off of the ground. In Figure 3-14, the PFD falls 

below the -258 dBW/m2

-Hz threshold interference level at distances greater than 27 km 

from the overhead BPL sources. In a letter to the FCC, NTIA requested that the 

Commission adopt an exclusion zone of 29 km around the boundary of the Very Large 

Array (VLA) radioastronomy site located in Socorro, New Mexico.[51] 

 

Figure 3-14: Power flux density relative to the distance from overhead BPL at 74 MHz 

(4 equal-power co-frequency BPL signal sources)

 

Figure 3-15 shows the results for the underground BPL case, assuming four 

equal-power co-frequency underground BPL sources radiating at the Part 15 limit in the 

direction of the receiving antenna. 
Figure 3-15: Power flux density relative to the distance from underground BPL at 74 MHz 

(4 equal-power co-frequency BPL signal sources)

 

For the underground BPL case, the power flux density falls below the threshold 

interference level at distances beyond 14 km from the underground MV power lines. 

This somewhat exceeds the 11 km protection radius associated with the 73.0-74.6 MHz 

exclusion zone around the boundary of the VLA radioastronomy location. From NTIA’s 

experience conducting field measurements on underground BPL systems, emissions 

levels are typically well below the Part 15 limits, and in many cases, the radiated BPL 

signal was not measurable.[52] 

3.6 SUMMARY 

Based on recommendations provided by NTIA resulting from these and earlier 

analyses, the Commission has specified excluded frequency bands, exclusion zones and 

consultation areas needed to prevent interference from BPL systems to certain federal 

radio operations in the 1.7 to 80 MHz frequency range. NTIA’s analysis shows that, at 

the distances corresponding to these protection area radii, BPL emissions are expected to 

result in only small increases in the noise floor of protected communications receivers, or 

PFD levels that fall below the interference protection requirement for sensitive 

radioastronomy or over-the-horizon radar receivers. 

 

These special safeguards provide an additional measure of interference protection 

beyond that afforded by field strength limits, prohibition of harmful interference from 

BPL systems, and compliance measurement provisions. The special protection 
provisions place only a minimal constraint on BPL deployment, as they impact only 

about two percent of the spectrum between 1.7 and 80 MHz. Additional special 

protection provisions may be needed if, at some time in the future, Access BPL devices 

are permitted to operate outside the 1.7 to 80 MHz frequency range. 

 

 
SECTION 4 

CASE STUDY OF POTENTIAL INTERFERENCE USING ADOPTED 

BPL RULES 

4.1 INTRODUCTION 

To examine the potential effectiveness of the rules for Access BPL, a case study 

was undertaken. The study modeled a residential neighborhood in which BPL devices 

had been installed on overhead power lines, with the radiation level from the BPL 

energized power line designed to meet FCC Part 15 rules and measurement guidelines 

adopted for Access BPL systems. Using this model, the potential noise floor increase 

seen by land mobile devices on roads adjacent to the line was determined. PFD levels 

resulting from BPL emissions that might be experienced at distant fixed receivers, such 

as for OTH radars, were also evaluated in this case study. 

 

The modeling effort detailed herein is not intended to be representative of a 

typical residential neighborhood; however, the power line and nearby roads are modeled 

using an actual residential area in which BPL devices have been installed, and this study 

is therefore instructive regarding conditions that might be encountered by nearby land 

mobile receivers and by distant receivers under the adopted rules. It is an extension of 

NTIA’s previous work that attempted to characterize typical interference potential due to 

BPL signals injected into a generic power line layout. 

4.2 METHODOLOGY 

The Commission’s BPL Report and Order specified measurement guidelines to 

enable BPL providers to determine compliance of their systems with FCC Part 15 limits. 

The relevant measurement guidelines are as follows: 

 

• For systems using data burst rates of at least 20 bursts per second, quasi-peak 

measurements are to be employed; 

• For frequencies above 30 MHz, electric field sensing antennas are to be used, 

with the measurement height from 1 to 4 meters to maximize the measured field 

at the Part 15 reference distance of 10 meters. Alternatively, the measurement 

may be made at 1 meter height, with a correction factor of 5 dB added to the 

measured field; 

• For frequencies below 30 MHz, a magnetic field sensing loop is to be employed 

at a measurement height of 1 meter, with the loop rotated about the vertical axis to 

maximize the measured field at the Part 15 reference distance of 30 meters; 

• Measurements should normally be performed at a horizontal separation distance 

of 10 meters from the overhead line; 
• For field strength measurements, the slant range distance between the overhead 

wiring carrying the BPL signals and the measurement antenna is used to compute 

a distance correction factor for adjusting the field strength measurement; 

• For signals with a bandwidth that is less than the midband frequency, 

measurement points are to be at the device and at 1⁄4-wavelength multiples of the 

midband frequency wavelength down the line, to a distance equal to one 

wavelength of the midband frequency; 

• For signals with a bandwidth exceeding the midband frequency, measurement 

distance down the line are to be extended in 1⁄2-wavelength of the midband 

frequency increments until the distance equals or exceeds 1⁄2 wavelength of the 

lowest in-band frequency. 

 

A computer model was constructed based upon an actual power line structure 

where NTIA conducted measurements of BPL emissions. The model was created with 

the help of in-situ observations and measurements, and was designed for simulation using 

NEC-4.1. As closely as possible and within program constraints, this model was 

designed to conform to the actual features of the power grid, including the use of catenary 

wires, correct placement of transformers loads, wire height and placement on power 

poles, grounding wires, riser, pole placement and wire junctions. The overall extent of 

the model was approximately 328 meters in the x-axis direction, and 435 meters in the yaxis direction. The modeled power line height was 12 meters. All wires were 12.6 

millimeters in diameter and given the conductivity of copper (5.8×107 S/m). The ground 

plane for the model (a flat earth structure beneath the wires) had characteristics typical of 

“good” ground (dielectric constant of 15.0, conductivity of 0.005 S/m). Due to the 

computational complexity of this model, the simulations were constrained to frequencies 

below 30 MHz. 

 

Simulations were focused on wideband and narrowband cases, based upon the 

FCC testing methodology stipulated above. For the wideband case, the BPL signal was 

assumed to cover the frequency range of 4 to 22 MHz, with a midband frequency of 13 

MHz. For the narrowband case, signals were assumed to occupy 4 MHz bandwidth, with 

midband frequencies ranging from 4 MHz to 28 MHz, in 4 MHz increments. 

4.2.1 Structure Injection Points 

NTIA’s elaborate overhead power line model has enough topological power-line 

features and sufficient geographic extent that simulations can be run for BPL devices 

placed at several points on the model. In this effort, three points in the power line 

structure were selected, as shown in Figure 4-1. 

 
Figure 4-1: Overhead view of the power line model depicting BPL injection points (red dots). 

Distribution transformers (impedance loads to neutral) are shown by black dots. 

 

In selecting the three points to be used, particular attention was paid to the 

magnitude and geographic extent of the radiated field around the power line structure by 

initial, wide-area NEC simulations of the magnetic field, as illustrated in Figure 4-2. In 

part, it may be assumed that the level of such radiation is influenced by the number and 

type of discontinuities (impedance and topological changes) encountered near each 

point. This methodology was used in order to better simulate expected radiation levels 

over a range of operating conditions and power line configurations. 

4.2.2 Simulation Frequencies 

For both narrowband and wideband cases, simulations were conducted at 2 MHz 

intervals including the lower and upper bounds of each band. The 4 MHz narrowband 

signals, centered at 4, 8, 12, 16, 20, 24 and 28 MHz, were simulated at three frequency 

points (lower bound, midband and higher bound), while wideband signals were simulated 

at 10 frequency points, from 4 to 22 MHz. The frequencies and midband points are 

detailed in Table 4-1. 

 

 

 
Figure 4-2: X-axis (horizontal) magnetic field due to BPL-energized power line (4 MHz), one meter 

off the ground, excited at point “3” and depicted in overhead view. Lighter shades represent 

stronger fields. 
Table 4-1: NEC simulation frequencies 

Frequency Band 

(MHz)

Midband Frequency 

(MHz)

Simulation Frequencies 

(MHz)

Narrowband Case

2-6 4 2, 4, 6

6-10 8 6, 8, 10

10-14 12 10, 12, 14

14-18 16 14, 16, 18

18-22 20 18, 20, 22

22-26 24 22, 24, 26

26-30 28 26, 28, 30

Wideband Case

4-22 13 4,6,8,10,12,14,16,18,20,22

4.2.3 Part 15 Scaling 

4.2.3.1 Measurement points 

As discussed previously, the rules adopted by the FCC specify measurement 

locations along the power line under two broad conditions: narrowband signals and 

wideband signals. For the narrowband case, measurement points are defined at the BPL 

energizing device, and 1⁄4, 1⁄2, 3⁄4, and 1 wavelength of the midband frequency away from 

the device down the power line. For the wideband case, the measurements are to 

continue down the power line at midband 1⁄2 wavelength intervals, until the total 

measurement distance exceeds 1⁄2 wavelength at the lowest frequency. 

 

Lines parallel to and 10 meters away from, the power line segments were derived 

from the model layout, and measurement points along those lines were identified. For the 

wideband case, 4 MHz was assumed to be the lowest operating frequency (corresponding 

to a wavelength of 74.95 meters), with a midband frequency of 13 MHz (23.06 meter 

wavelength). As Table 4-2 illustrates, the measurement regime indicates measurements 

in this case should be made at points out to 2 wavelengths distant at the midband 

frequency from the BPL device. 

 

Table 4-2: Distances down the line from BPL device for wideband-case Part 15 measurement points 

Wavelength from 

BPL Device 0 1/4 1/2 3/4 1 1 1/2 2

Distance Down 

Power Line (m) 0 5.765 11.531 17.296 23.06 34.592 46.123

 

For the narrowband case, simulations were run at locations along the power line 

appropriate for each band’s midband frequency (Table 4-3). 

 

 

 
Table 4-3: Distances down the line from BPL device for Part 15 measurement points in narrowband 

case, by frequency 

Distance Down Power Line, by Wavelength 

(m)

Narrowband Center 

Frequency (MHz)

0 1/4 1/2 3/4 1

4 0.000 18.738 37.475 56.213 74.950

8 0.000 9.369 18.738 28.106 37.475

12 0.000 6.246 12.492 18.738 24.983

16 0.000 4.684 9.369 14.053 18.738

20 0.000 3.748 7.495 11.243 14.990

24 0.000 3.123 6.246 9.369 12.492

28 0.000 2.677 5.354 8.030 10.707

 

Coordinates for points along the power line, 10 meters distant from the line (as 

specified in the BPL Report and Order, Appendix C) were calculated at the distances 

from the BPL injection device as specified above. Exceptions to this scheme were points 

at which a power line “T” branch or end caused a calculated point to be closer or farther 

than 10 meters from the power line. When these points were encountered, simulation 

results were not used. 

4.2.3.2 Scaling output power to meet FCC Part 15 limits 

Initial NEC simulations were used to determine the power output of each modeled 

BPL device that would meet Part 15 limits using the adopted BPL measurement 

guidelines. For the frequencies considered in this analysis (all below 30 MHz), the FCC 

Part 15 radiated emissions limit, E30m, is specified as 30 μV/m at 30 meters horizontal 

distance.[53] To adjust electric field strength levels computed at the 10 meter distance 

specified in the Access BPL measurement guidelines, the slant range between the power 

line and measurement point must be used in conjunction with a 40 log correction factor. 

With the modeled power line height of 12 meters and measurement point height of one 

meter, the slant range adjustment results in an extrapolated limit at 10 meters as shown 

below using Equations 2-2 and 2-3. 

 

 

For all frequencies below 30 MHz, the Part 15 measurement bandwidth is 

specified as 9 kHz. 

 

The BPL energized power line radiation was simulated for the wideband case at 

the specified frequencies within the band (See Table 4-1). Magnetic field values at the 

geographic measurement points specified in the Part 15 measurement guidelines for 

Access BPL systems were calculated and converted to electric field values following 

Equation 2-1. The maximum of these electric field values calculated by NEC over all 
measurement points and frequencies (Emax) was subsequently divided by E10m to obtain a 

scaling factor, “A”, used to scale the electric field strength data in the wideband case. 

 

 (Equation 4-1) 

 

For the narrowband case, simulations were run for all specified frequencies within 

each band to determine the magnetic field values at the appropriate measurement points 

for each band (See Table 4-1). As with the wideband case, all values were converted to 

electric field values, and the maximum electric field value at any measurement point and 

frequency for each band was divided by E10m to obtain the scaling factor, A, for each 

band. 

4.2.4 Simulation of Potential Interference 

After scaling the output power to meet the Part 15 limits for each frequency, 

bandwidth case, and BPL device location, the interference potential for each situation 

was simulated. Field-strength values were obtained from simulations both along and 

away from the modeled power line. From these results, noise floor level increases for a 

simulated land-mobile receiver located on a road next to the power line were calculated. 

Additionally, PFD calculations were carried out to determine the possible impact upon a 

radar receiver at a large distance from the power line. 

4.2.4.1 Ambient noise levels 

Noise levels calculated for this analysis were median values for the location in 

question over time of day and season. To simulate the local (i.e., private residence) BPL 

operating conditions under which land mobile receivers might encounter BPL signals, the 

residential manmade noise conditions shown in Table 4-4 were used. As in the NTIA’s 

Phase 1 Study, ambient noise was calculated using the Institute for Telecommunication 

Sciences NOISEDAT computer program.[54] A bandwidth of 2.8 kHz was used 

consistent with that of a land mobile receiver. 
Table 4-4: Ambient noise power, by frequency, in a 2.8 kHz bandwidth 

4.2.4.2 Simulation of increased noise levels along an overhead power line 

NTIA analyzed the noise floor increase that may be experienced by a land mobile 

radio operating in close proximity to a BPL-energized MV overhead power line. The 

analysis was undertaken to compute the percentage of points along the power line that 

experienced a given increase in the noise floor above the ambient level.[55] To 

accomplish this, NTIA ran NEC simulations to obtain electric field values around the 

modeled power line. The points at which the electric field was calculated were in the 

path of roads found along the actual power line upon which the model was based, as 

shown in Figure 4-3. Electric field strength values were computed at two meters off the 

ground to simulate the height of a vehicle-mounted land mobile radio antenna, and at one 

meter increments along the path. The land mobile radio system was assumed to be using 

a vertical whip antenna. Accordingly, only the z-axis (vertical) electric field values were 

used. 

 

The path around the modeled power line along which electric field strength values 

were calculated varied in distance from the power line. Along one section of the modeled 

power line, the horizontal distance from the power line to the center of the road was 

approximately 3 meters, and ranged from 30 to 48 meters along another section. The 

path along which calculations were performed passed under a branch of the power line 

model at one point (Figure 4-3). 

 

 

Frequency (MHz) Noise Power, NdBW (dBW)

2 -104.28

4 -112.08

6 -116.98

8 -121.03

10 -124.13

12 -126.28

14 -128.28

16 -130.08

18 -131.63

20 -132.93

22 -134.13

24 -135.18

26 -136.13

28 -137.03

30 -137.83
Figure 4-3: Path of along-the-line land mobile simulations (thick grey line). This path corresponds to 

that followed by actual road next to the power that the model is based on, depicted in overhead view. 

 

Once derived, the electric field values were translated into received interfering 

signal power using Equation 4-2. 

 

 (Equation 4-2) 

where 

P is received BPL signal power, in dBW; 

E is the calculated vertical electric field strength, in V/m; 

 A is the Part 15 electric field scaling factor determined for the 

narrowband case, and for the wideband case, as described in 

Section 4.2.3.2; 

F is the measurement frequency, in MHz; 

Gr is the gain of the receiving antenna, in dBi; 

BW is the ratio of receiver to measurement bandwidth; 

φ is the average duty cycle; and 

δ is a quasi-peak to RMS measurement factor. 
As in NTIA’s Phase 1 Study, the average duty cycle (φ) was taken to be 55 

percent, which was midway between an always-on (100 percent) downstream signal and 

an intermittent (10 percent) upstream customer-to-internet signal. The gain (Gr) of the 

receiving antenna was taken to be a constant 0 dBi across all frequencies, and the ratio of 

receiver bandwidth to measurement bandwidth (BW) was 2.8 kHz to 9 kHz, 

respectively. Finally, to compensate for differences between ambient noise levels 

expressed in RMS values and BPL signal radiation measured using quasi-peak detection, 

a measurement factor (δ) adjustment of -2 dB was applied to the calculated received BPL 

signal power.[56]

 

The increase in the noise floor due to BPL emissions, or (I+N)/N, was calculated 

using Equation 4-3. 

 

 (Equation 4-3) 

where 

 P is the received BPL signal power, in dB, from Equation 4-2; 

 N is the ambient noise power, in dB; and 

I is the interfering signal, in dB. 

 

The results of these calculations are used to determine the percentage of geographic 

locations that exceed given thresholds of noise floor increase. 

4.2.4.3 Simulation of PFD levels away from an overhead power line 

NTIA analyzed the PFD levels due to BPL emissions that may be seen by fixed 

receivers, such as OTH radar receivers, at increasing distances from the power line 

structure used in this case study. Both NEC and ITM were used to derive PFD values at 

1 km intervals on radials extending out from the power line injection points. The radials 

were spaced 1 degree apart, for a total of 360 radials, and extended from 1 to 50 km from 

the origin. 

 

Electric field strength values were calculated first using Equation 4-4 along each 

radial at 42.7 meters height, the height of the assumed receiver antenna. NEC 

calculations were performed to a distance of 10 km from the origin, a distance chosen to 

minimize variations due to the large size of the power line layout and diffraction effects 

due to the curvature of the earth. Beyond 10 km, ITM was used to calculate the basic 

transmission loss due to distance separation and diffraction of the RF signal over a 

spherical earth. 

 

 (Equation 4-4) 

where 
ESUM is electric field strength vector, in V/m; 

Ez is the z-axis (vertical) component of electric field, in V/m; 

Eφ is the phi-axis (perpendicular to radial and z-axis) component of 

electric field, in V/m; and 

Eρ is the rho-axis (along the radial) component of electric-field, in 

V/m. 

The PFD was then derived from ESUM using Equation 4-5. 

 

 (Equation 4-5) 

 where 

 A is the Part 15 electric field scaling factor determined for the 

narrowband case, and for the wideband case, as described 

in Section 4.2.3.2; 

 BW is the specified Part 15 measurement bandwidth (9 kHz for 

signals below 30 MHz); and 

 PFDNEC is the power flux density computed at various distances, ρ, 

along the radials, in dBW/m2-Hz. 

ITM transmission loss data and the PFD values at 10 km were combined to 

calculate PFD values from 10 km out to 50 km. The ITM results used the same ground 

parameters as NEC, and the same power line height of 12 meters and an assumed receiver 

antenna height of 42.7 meters.[57] ITM input parameters are detailed in Table 4-5. 

 
Table 4-5: ITM input parameters

Input Variable Value

Frequency 2-30 MHz in 2 MHz steps

Antenna Heights Transmitter – 12 m, Receiver – 42.7 m

Siting Criteria Transmitter – Random, Receiver – Very 

Careful

Terrain Irregularity Factor, Δh 30 m

Polarization Horizontal

Relative Permittivity 15

Ground Conductivity 0.005 S/m

Climate Continental Temperate

Surface Refractivity 301 N-units

Percent Time 50.0%

Percent Location 50.0%

Percent Confidence 50.0%

Mode of Variability Individual

 

To determine the PFD values accounting for diffraction losses that come into play 

at large distances from the power line, the transmission losses beyond 10 km calculated 

by ITM were scaled relative to the value that ITM computed at 10 km (Equation 4-6). 

Within 10 km of the power line, the adjusted PFD was the same as the PFD computed 

using NEC electric field strength directly (Equations 4-5 and 4-7a). Beyond 10 km, the 

scaled ITM loss values, at each distance, and the PFD computed at 10 km from NEC 

were used to compute the adjusted PFD 

(Equation 4-7b). 

 (Equation 4-6) 

 

 (Equation 4-7a) 

 (Equation 4-7b) 

4.3 

RESULTS 

A summary of the simulation conditions described in Section 4.2 is provided in 

Table 4-6. The results for computing the receiver noise floor increase along the 

simulated power line are provided in Section 4.3.1. The results for analyzing the PFD the 

might be seen by a fixed receiver located at some distance away from the power line are 

described in Section 4.3.2. 

 

 

 
 

 

Table 4-6: Simulation conditions

Overhead Power Line Model

Conductors 3 power conductors, catenary wiring between simulated power 

pole locations. Multi-grounded neutral conductor. Primarily 

vertical orientation, switching to horizontal at one location. 

Four simulated risers connecting to simulated underground 

load.

Conductor Material Copper

Conductor Thickness 12.6 mm (approx. AWG 4/0)

Conductor spacing 0.6 m with neutral conductor 1.2 m below

Model Size 328.2 m in the ‘x’ direction, 435 m in the ‘y’ direction

Height above ground Power conductors at 12 m with neutral wire at 9.6m

Coupler location A coupler was simulated roughly halfway down each of the 

two main branches and another at the junction of these 

branches

Source 1 Volt in series

Load 7 simulated transformer loads (3 Ω + 5 μH) between power 

conductors and neutral. Risers had simulated 

30 Ω loads between power conductors and ground.

BPL average duty cycle 55%

QP-to-RMS conversion -2 dB

Ground Conditions

Conductivity σ = 0.005 S/m

Relative permittivity εr = 15

Simulation Frequencies

Land Mobile Receiver 2 -30 MHz

Fixed (e.g., OTH Radar) 2 - 30 MHz

Receiver Antenna

Land Mobile Vertical Whip

Gain towards power line 0 dBi

Height 2 m

Fixed (e.g., OTH Radar)

Gain towards power line 0 dBi

Height 42.7 m

Noise Conditions Residential, as per Table 4-4

Land Mobile Simulation For Noise Floor Increase ((I+N)/N) Analysis

Victim Receiver Location Center of simulated roadway

Power Line Branch Parallel to x-axis Parallel to y-axis

Dist. From Power Line 3 m Ranging from 30 to 48 m
ITM Conditions For PFD Analysis

Frequency 2 – 30 MHz

Transmitter (Power line) Receiver (Fixed)

Antenna Heights 12 m 42.7 m

Siting Criteria Random Very Careful

Terrain Irregularity Factor, 

Δh

30 meters

Polarization Horizontal

Relative Permittivity 15

Ground Conductivity 0.005 S/m

Climate Continental Temperate

Surface Refractivity 301 N-units

Percent Time 50.0%

Percent Location 50.0%

Percent Confidence 50.0%

Mode of Variability Individual

 

4.3.1 Receiver Noise Floor Increase Along the Power Line 

Results were considered from simulations of potential interference to a land 

mobile receiver on roads next to the simulated power line for all three BPL device 

injection points across both narrowband and wideband systems, and across frequencies in 

the 2 to 30 MHz range. The results are presented in terms of the percentage of points 

along the BPL energized power line that increased the receiver noise floor by various 

levels. 

 

4.3.1.1 Receiver noise floor increase relative to the injection point 

The results shown in Figures 4-4 and 4-5 illustrate the percentage of simulated 

points along the modeled power line that result in a given level of noise floor increase for 

all simulation frequencies shown in Table 4-1 for narrowband and wideband BPL signals, 

respectively. These figures show that the percentage of locations resulting in a given 

increase in the noise floor varied somewhat by injection point. 

 

The most notable feature of the data is the sharp divergence in the percentage of 

points for a noise floor increase of 30 dB or more seen by the three modeled injection 

points. The close proximity of Injection Point 2 to the road and to a modeled transformer 

load likely accounts for the highest percentages of locations exceeding a 30 dB increase 

in the noise floor. Injection Point 3 is positioned close to the intersection of three power 

lines, but at least one utility pole away from nearby transformer loads. This may also 

have resulted in the increase in the receiver noise floor associated with this point being 

greater than that of Injection Point 1. Injection Point 1 was located farthest away from 

the street in this model, and one or more utility poles away from any discontinuities such 

as transformer loads. 

 
Figure 4-4: Increase in receiver noise floor [(I+N)/N] as a function of the percentage of measurement 

points around the power line for narrowband BPL signals 

 

 

 

Figure 4-5: Increase in receiver noise floor [(I+N)/N] as a function of the percentage of measurement 

points around the power line for wideband BPL signals 
4.3.1.2 Receiver noise floor increase as a function of frequency 

For both narrowband and wideband BPL signals, variation was noted in the 

calculated results over frequency. Table 4-6 shows the results for narrowband signals 

and Table 4-7 shows results for wideband signals based on simulations for Injection Point 

3. 

 

Table 4-6: Percentage of simulated points along the power line at which the receiver noise floor was 

increased by at least the specified amount for narrowband BPL signals 

Frequency Noise Floor Increase (dB)

Band (MHz) 3 10 20 30 40 50

2-6 95.22% 67.97% 34.29% 9.50% 0.00% 0.00%

6-10 95.83% 80.59% 38.81% 4.78% 0.00% 0.00%

10-14 97.39% 82.30% 47.41% 12.57% 0.00% 0.00%

14-18 98.94% 87.53% 61.04% 20.97% 2.46% 0.00%

18-22 98.94% 92.86% 63.90% 20.76% 1.56% 0.00%

22-26 98.49% 90.60% 49.17% 5.68% 0.00% 0.00%

26-30 99.20% 95.22% 60.78% 14.98% 0.00% 0.00%

 

 

Table 4-7: Percentage of simulated points along the power line at which the receiver noise floor was 

increased by at least the specified amount for wideband BPL signals 

Mid-band Noise Floor Increase (dB)

Frequency (MHz) 3 10 20 30 40 50

4 93.51% 56.71% 22.02% 1.81% 0.00% 0.00%

6 88.99% 60.94% 28.66% 0.00% 0.00% 0.00%

8 99.40% 87.03% 43.59% 3.62% 0.00% 0.00%

10 95.78% 81.75% 37.71% 3.17% 0.00% 0.00%

12 96.08% 79.49% 50.38% 7.69% 0.00% 0.00%

14 98.19% 78.58% 47.96% 14.78% 0.00% 0.00%

16 98.04% 82.20% 42.53% 0.60% 0.00% 0.00%

18 99.70% 97.89% 82.81% 39.06% 4.68% 0.00%

20 98.64% 92.91% 61.24% 11.46% 0.00% 0.00%

22 98.34% 86.73% 46.30% 10.86% 0.00% 0.00%

4.3.2 Power Flux Density Away from the Power Line 

The away-from-the-line analysis computed the PFD seen by a fixed receiver, such 

as an OTH radar receiver, as a function of distance of the receiver from the modeled 

Access BPL system. The PFD as a function of distance was determined for the three 

modeled BPL injection points and frequency bands for narrowband and wideband BPL 

signals. In considering these results, NTIA looked at median values for both narrowband 

and wideband BPL signals across radials leading away from the power line model and 

across the 2 to 30 MHz frequency band. 

 

Figures 4-6 and 4-7 depict median PFD versus distance from the origin for all 

simulated in-band frequencies for the three BPL injection points described in Section 
4.2.2. Variation in PFD as a function of horizontal distance for the different injection 

points on the structure was very small and did not exceed 3 dB at any given distance from 

the power line model. 

Figure 4-6: Power Flux Density as a function of distance from the origin for narrowband BPL signals 

across all simulated in-band frequencies

 
Figure 4-7: Power Flux Density as a function of distance from the origin for wideband BPL signals 

across all simulated in-band frequencies

When considering frequency as a factor, the median (with respect to azimuth) 

PFD results from Injection Point 3 as a function of distance take on more variation. As 

shown in Figures 4-8 and 4-9 for the narrowband and wideband BPL signals, 

respectively, the maximum variation as a function of frequency was approximately 13 dB 

at 1 km distance for narrowband BPL signals and nearly 15 dB at 4 km distance for 

wideband BPL signals. 

 
Figure 4-8: Power Flux Density as a function of distance from Injection Point 3 for narrowband BPL 

signals, organized by frequency band 

 

Figure 4-9: Power Flux Density as a function of distance from Injection Point 3 for wideband BPL 

signals, organized by frequency 

 

For the narrowband BPL signals shown in Figure 4-8, the PFD level at any given 

distance tends to increase as the frequency band increases. This trend results primarily 
from increasing radiated power as frequency increases. In other words, the total radiated 

power of this model tends to increase as frequency increases, while still meeting the Part 

15 electric field strength limit as measured using the Commission’s measurement 

guidelines. For wideband BPL signals, where Part 15 scaling relies on the measurement 

locations associated with the midband frequency (Table 4-2), the estimate of electric field 

strength for some individual frequencies may be somewhat less accurate. This may be 

observed in the variability of PFD levels for each frequency band shown in Figure 4-9, 

where the calculated PFD levels do not consistently increase with frequency. 

4.4 SUMMARY 

The NTIA case study illustrates application of the Commission’s Part 15 rules and 

measurement guidelines for Access BPL systems. NTIA analyzed the potential impact 

on mobile radiocommunication systems close to an overhead BPL-energized power line 

emitting RF energy at the Part 15 limit, as well as to fixed radiocommunication systems, 

(such as OTH radars) at great distances from the line. While previous analyses made use 

of simple power line models, this case study employed an elaborate power line model 

that included a variety of features found in an actual MV power distribution system 

carrying BPL signals. 

 

The results of this analysis are comparable to those found in NTIA’s earlier 

investigations, and indicate that the Part 15 measurement procedures described in the 

BPL Report and Order appear to estimate adequately the electric field strength levels 

around the power line near ground level.[58] 

 
SECTION 5 

IONOSPHERIC PROPAGATION AND AGGREGATION OF BPL 

EMISSIONS 

5.1 INTRODUCTION 

Thus far, NTIA’s Phase 2 Study regarding BPL interference potential has focused 

on local interference due to a small quantity of co-frequency BPL devices. Of additional 

interest, however, is the potential effect of a large scale BPL deployment on aggregate 

noise levels over a national scale. An aggregate effect from BPL interference, if any, 

would occur due to ionospheric or “sky wave” propagation. 

 

This sky wave phenomena, in which HF signals are refracted by charged particles 

in the ionosphere and returned to earth hundreds or thousands of miles away, is the same 

process through which short wave communications can be heard around the globe. Since 

current BPL systems make use of HF frequencies, and since modeling of BPL-energized 

power lines indicates much of the BPL emissions appear to radiate in an upward 

direction, these HF BPL emissions have the potential to travel many miles from their 

source. Moreover, because a given listening point may receive radiated BPL emissions 

from many sources, it is conceivable that an aggregation of signals could occur, raising 

the receiver noise floor level and rendering weak, desired signals unintelligible. In 

general, ionospheric propagation occurs for frequencies between 1.7 MHz and 30 MHz, 

as discussed in the NTIA Phase 1 Study.[59] 

 

The analysis presented in this section expands upon and clarifies results presented 

in the NTIA Comments on the BPL NPRM.[60] These results have been augmented by 

additional modeling and application of the measurement guidelines released in the 

Commission’s BPL Report and Order. 

5.2 ANALYTICAL MODELING OF SKY WAVE 

PROPAGATION 

5.2.1 Background 

In its BPL comments, NTIA detailed a preliminary analysis of aggregation of 

BPL emissions via ionospheric propagation. That analysis employed the VOACAP HF 

statistical propagation prediction software and overhead power line models using the 

NEC software. The goal of that effort was to obtain a preliminary determination as to 

whether noise-like BPL emissions, propagated by ionospheric refraction and aggregated 

at a point, could present a viable interference concern. 

 

NTIA’s initial ionospheric aggregation analysis consisted of two parts: an effort 

to determine probable “worst-case” conditions for aggregation, and a set of simulations 
of widespread BPL deployments on overhead MV power lines and possible aggregation 

effects. 

 

To estimate worst-case aggregation conditions, point-to-point VOACAP 

propagation calculations were used between several sites in North America over a wide 

range of times of day, months of the year and frequencies. NTIA then selected the 

conditions that produced the highest signal-to-noise levels at the various receive points to 

simulate widespread aggregation. 

 

NTIA’s aggregation simulation employed VOACAP in its “area” mode to 

calculate aggregate emissions received at multiple points from widespread BPL 

deployments. In the geographic center of every county in the United States, NTIA placed 

effective BPL emitters, each representing the total BPL emissions from its respective 

county. In the NTIA Comments, the power output of each effective BPL emitter was 

derived from NEC modeling of a simple overhead power line model described in the 

NTIA Phase 1 Study.[61] The model consisted of three 340-meter-long straight wires 

terminated together at the ends through impedances. In that report, NTIA calculated the 

radiated power output from the straight-wire power line model which would result in 

electric fields that met Part 15 limits, and the result was scaled by NTIA’s deployment 

model and county population to arrive at the power output of each effective BPL emitter. 

The emitters were then given frequency-dependent, far-field radiation patterns based 

upon an elaborate overhead power line model developed using the NEC software.[62]

 

Propagation simulations were sequentially run for each emitter to a fixed grid of 

receive points covering CONUS, and the results were summed in the power domain. 

NTIA ran these simulations for the suspected worst-case sets of conditions derived from 

the point-to-point simulations described above. 

 

This preliminary analysis led NTIA to conclude potential interference due to 

ionospheric aggregation of BPL signals was not a near-term challenge. 

 

5.2.2 Approach 

5.2.2.1 Power Line Models 

 

For this report, NTIA determined new radiated power levels for each effective 

BPL emitter using the elaborate overhead power line model. Additionally, these power 

levels were calculated using the new measurement guidelines adopted in the BPL Report 

and Order.[63] Thus, the new simulations were based entirely upon the elaborate overhead 

power line model, rather than a combination of this model and the simplified power line 

model from NTIA’s Phase I Study. This new approach resulted in different (but 

comparable) radiated power levels than those used in the NTIA Comments. Table 5-1 

shows the values of radiated power as a function of frequency used in this study, along 

with the values previously presented in the Technical Appendix to the NTIA Comments. 

 
NTIA created an additional NEC model of an underground BPL system (Figures 

5-1 and 5-2). Similar propagation analyses were completed over a large sample of hours 

of the day, frequencies, months of the year and solar conditions (more than 1,300 sets of 

conditions), including the same conditions that resulted in the greatest aggregated 

interference-to-noise ratios using the overhead power line model as an emitter. As with 

the overhead model, NTIA used NEC to derive frequency-dependent directive-gain 

radiation patterns and radiated power necessary to meet Part 15 limits from the 

underground model. Radiated power calculations were again performed using the new 

BPL measurement guidelines in the BPL Report and Order.[64] The radiated power levels 

are listed in Table 5-1. 

 

Figure 5-1: Underground power line model with ground removed. The underground line, comprised 

of three neutral wires surrounding a dielectric-insulated central wire, extends 340 meters end to end 

 

 
Figure 5-2: Underground power line model with ground included. The visible wireframe box 

represents a pad-mounted transformer, in which the BPL source is installed. 

Table 5-1: BPL structural radiated power at Part 15 limit

Frequency

(MHz)

Radiated Power (dBW/Hz) 

Overhead

(from Technical Appendix)

Radiated Power 

(dBW/Hz)

Overhead

Radiated Power 

(dBW/Hz)

Underground

2 -105.49 -103.04 -94.26

4 -104.87 -106.71 -87.84

6 -104.27 -104.38 -84.66

8 -103.68 -102.99 -82.73

10 -103.11 -102.89 -83.29

12 -102.55 -102.93 -79.38

14 -102.01 -104.06 -78.43

16 -101.49 -106.32 -74.75

18 -100.98 -97.48 -75.16

20 -100.49 -103.48 -79.52

22 -100.01 -104.29 -81.67

24 -99.55 -101.04 -82.24

26 -99.11 -105.71 -82.45

28 -98.68 -100.98 -83.47

30 -98.27 -98.04 -84.28

 

Greater NEC-calculated radiated power from underground structures is not 

unexpected, as ground losses subsequently attenuate this power significantly. Thus, it is 

to be expected that NTIA’s underground model radiated significantly more power than 

overhead systems while meeting Part 15 limits. With both the overhead and underground 
models, increased variability of radiated power with frequency is largely due to the vast 

increase in complexity of the model used over previous work. 

 

The BPL Report and Order specified that compliance measurements should take 

place at 1⁄4 wavelength intervals down the power line from the BPL device, to a distance 

of one wavelength of the mid-band frequency, at a measurement height of one meter.[65] 

To derive the original Part 15 values used in the analysis presented in the NTIA 

Comments, field strength values were calculated at 0.5 meter intervals along the entire 

length of the power line. Thus, the new methodology makes use of far fewer points to 

find peak field strength values around the power line. Nonetheless, the derived radiated 

power is in remarkable agreement with the previously derived values reported in the 

Technical Appendix to the NTIA Comments. 

 

The radiated power levels were derived by exciting the NEC models in question 

using a unit voltage source, finding the magnetic or electric field values through NEC 

simulation at appropriate points around the models as specified in the BPL measurement 

guidelines, and scaling all subsequent electric field values by the dividend of calculated 

electric field divided by the Part 15 limit. To translate the scaling to the power domain, 

NEC-calculated radiated power levels were scaled by the square of this factor. 

 

5.2.2.2 Use of Voice of America Coverage Analysis Program 

 

As in the NTIA Comments, NTIA calculated BPL interference and man made 

noise power values using VOACAP’s area mode in a fixed 31×31-point grid of receiving 

points covering CONUS and centered on Kansas City, Missouri.[66] NTIA again assumed 

BPL deployment densities based in part on U.S. Census data to simulate effective BPL 

emitters in the geographic center of each county in the United States (including Alaska 

and Hawaii).[67] As before, these emitters were given frequency-dependent directive-gain 

radiation patterns calculated using the elaborate NEC overhead power line model and 

located in the geographic center of each county. The radiation patterns used were 

arithmetically averaged in azimuth to simulate the random orientation of multiple BPLenergized power lines represented by each effective emitter. 

 

In this study, NTIA ran full ionospheric aggregation simulations over a 

comprehensive set of more than 8,500 sets of conditions (including all months of the 

year, hours of the day, low and high levels of solar activity and frequencies from 2 to 30 

MHz in 2 MHz increments). NTIA used these simulations to calculate the Interferenceplus-Noise-to-Noise ratio, or (I+N)/N, conditions due to large numbers of deployed BPL 

devices.[68] The results presented here were examined in terms of sets of conditions 

producing worst-case increases to the local receiver noise floor. 

 

VOACAP reports results of propagation in terms of signal-to-noise ratio (SNR). 

Table 5-2 indicates how the SNR values reported by VOACAP translate into noise floor 

increases. 
 

Table 5-2: Noise floor increase [(I+N)/N] as a fuction of Signal-to-Noise Ratio 

Noise floor increase, (I+N)/N (dB) SNR (dB)

3 0

1 -5.868

0.5 -9.135

0.1 -16.327

0.05 -19.363

0.01 -26.373

0.005 -29.386

 

5.3 SIMULATION CHARACTERISTICS 

NTIA ran simulations both with the Smoothed Sunspot Number (SSN) parameter 

set to a high value (150) to simulate excellent propagation characteristics during the peak 

of the 11-year solar cycle, and to a low value (25) to simulate depressed propagation 

characteristics at the low point in the solar cycle. Because of software design, all receive 

points used VOACAP’s quarter-wave vertical monopole antenna (type 22) over ground 

with dielectric constant εr=15 and conductivity σ set to 0.005 S/m.[69] In reality, ground 

characteristics vary in the United States, ranging from very poor (εr=3 and σ= 0.001 S/m) 

to excellent (εr=20 and σ=0.030 S/m). 

 

The manmade noise level was set to remote or quiet rural levels (-164 dBW/Hz at 

3 MHz) at all receive points, to best address receiving conditions at many federal 

sites.[70] As with receive-point antennas, software design allows one manmade noise 

level to be assigned to all receive points in VOAAREA’s calculation grid. Actual 

manmade noise levels in the United States can vary from quiet rural conditions to the 

very high noise levels that can be found in industrial areas. Furthermore, some 

preliminary studies now indicate that actual background noise levels at HF frequencies 

may have increased since benchmark noise studies were completed several decades 

ago.[71]

 

NTIA individually scaled the NEC-calculated radiated power levels by the 

number of active BPL devices expected to serve the urban households in each county in 

the United States. Urban households were used in this analysis as they present greater 

deployment densities than rural households, and as such, are more likely to be the bulk of 

early deployments of Access BPL service. As in the earlier analysis, NTIA assumed that 

a BPL injector had the data handling capacity to support an average of 30 customers, and 

1 of 4 urban households was a BPL customer. In other words, one BPL injector was 

assumed per 120 urban households. With nearly 85 million urban households in the 

United States, this assumption resulted in a total of over 705,000 modeled BPL devices in 

this analysis.[72] 
Several other factors were taken into consideration when predicting the receiver 

noise floor increase. First, NTIA considered that not all BPL devices will operate at the 

Part 15 limit; therefore, the average radiated signal was assumed to be 4 dB below the 

Part 15 limit. Second, the analysis was based on root-mean-square (RMS) values; 

therefore an adjustment was made to convert the quasi-peak BPL signal level to an RMS 

level.[73] Third, since the devices in the system do not all operate at the same frequency, 

an allowance of 6 dB was given (i.e., 1 in 4 BPL injectors are assumed to be cofrequency). Finally, the assumed duty cycle of BPL devices was set at a mean of 55 

percent. These adjustments to the BPL radiated power levels are listed in Table 5-3. 

 

Table 5-3: Adjustment Factors for Access BPL Devices 

Factor Adjustment (dB)

Devices operating at levels below Part 15 limits 4

Quasi-Peak to RMS Conversion 3

Co-frequency distribution factor 6

Duty Cycle 2.6

Total 15.6

 

The receive points in the VOAAREA calculation grid used 1 Hz bandwidths (set 

by adjusting the radiated interfering BPL signal power of each transmitting point to the 

power in dBW/Hz). The noise power levels provided by VOAAREA were in dBW/Hz. 

The received signal power from all effective BPL emitters at a given receive point was 

summed in the power domain independent of the noise power level, and the resulting 

summed BPL interfering power and the noise power at that point were used to calculate 

interference-to-noise. Thus, the aggregate interference-to-noise ratio at a point was into a 

1Hz bandwidth. 

 

Simulations were run across frequencies from 2 to 28 MHz (in 2 MHz 

increments), for all months of the year and for all hours of the day (approximately 4300 

simulations). Table 5-4 summarizes the assumptions listed above as they were applied to 

this simulation. 

 

Table 5-4: Simulation conditions 

Effective BPL emitters Overhead Underground

Excitation Voltage source on single line, 

centrally located

Voltage source in pad-mounted 

transformer, centrally located

Far field pattern

Source NEC-4.1 overhead model NEC-4.1 underground model

Variability Averaged over azimuth, variable by elevation and frequency

Type Directive gain

Power level

Source NEC-4.1 overhead model NEC-4.1 underground model

Structure emissions 

limits

Limited by Part 15 limits, as measured using BPL measurement 

guidelines

County-level scaling Scaled by urban households in county

Parameter used NEC-4.1 “radiated power” value (specified as output power after 
structure losses, but not ground losses, are considered)

Placement Geographic centers of all counties in the United States

Receive antennas

Antenna type Quarter-wave monopole (VOACAP type 22)

Ground conditions “Average” ground

Conductivity 0.005 S/m

Relative permittivity 15

Placement 31x31 grid of receive points throughout CONUS

Noise “Quiet rural” noise conditions (-164 dBW/Hz)

Simulation

Frequencies From 2 to 30 MHz in 2 MHz steps

Times of day From 0 to 23 hours UTC in 1-hour increments

Months of year From January to December

Solar conditions Smoothed Sunspot Numbers (SSN) 25 and 150

Primary path geometry Short path

Calculation methodology Short/long path smoothing

Calculated parameters Received signal strength (SDBW), received noise (NDBW)

Power Adjustment 

Factor

-15.6 dB (detailed in Table 5-3)

5.4 SIMULATION RESULTS 

In order to gauge whether a given aggregated BPL signal level presents a risk of 

harmful interference to a radiocommunication receiver, NTIA considered two threshold 

values of (I+N)/N, or receiver noise floor increase.[74] The lower threshold, a 1 dB 

increase in the noise floor (corresponding to a BPL interference-to-noise ratio of 

approximately -5.9 dB), was chosen as the level at which some harmful interference 

might occur. The higher threshold, increasing the noise floor by 3 dB (a BPL 

interference-to-noise ratio of 0 dB), was selected as a level at which harmful interference 

was considered to be a significant risk. 

 

Analysis of the impact of BPL aggregation was done by combining the BPL 

signal levels of the modeled overhead and underground BPL systems with the 

background noise levels, such that the combination met the noise floor increase 

thresholds listed above. This analysis enabled NTIA to examine the ionospheric 

aggregation effects while varying the relative numbers of overhead and underground 

systems. 

5.4.1 Comparison of Overhead and Underground Analysis Results 

The simulations found overhead systems produced aggregated signal levels 

greatly in excess of underground systems, even when both classes of systems were 

adjusted to meet Part 15 limits. The median value for overhead aggregated BPL signal 

level was approximately 20 dB higher than that of an equal number of underground 

systems, given the same ionospheric propagation characteristics, over all the conditions 

modeled. This finding suggests that, where feasible, installation of BPL devices 

operating in the 1.7 to 30 MHz frequency range on underground wiring could have 
significant advantages over the same devices operating on overhead systems, from the 

standpoint of signal aggregation due to ionospheric propagation. 

 

The relative impact of overhead and underground BPL aggregation can be seen 

graphically in the following results. Figures 5-3 and 5-4 illustrate the number of 

overhead plus underground devices needed to cause a worst-case 1 or 3 dB increase in 

the noise floor at any geographic location in the United States under best propagation and 

lowest local noise floor conditions. 

 

For these graphs, ionospheric aggregation modeling was used to derive sets of 

conditions for both low and high solar activity during which the greatest ratios of signalto-noise level due to aggregated BPL was produced. For all other sets of conditions and 

geographic locations, calculated aggregation resulted in less impact to the noise floor. 

Thus, for most calculated conditions, more BPL devices would be required to produce the 

same impact on the local noise floor as that illustrated in Figures 5-3 and 5-4. 

 

Calculations for periods of high solar activity indicated that maximum aggregated 

BPL signal levels occur primarily at higher frequencies in the HF band (18-30 MHz) 

during mid-to-late afternoon hours in the fall and winter. Calculations using low solar 

activity conditions found maximum aggregated BPL signal levels primarily at lower 

frequencies in the HF band (4-8 MHz). As was indicated by calculations assuming high 

solar activity conditions, maximum aggregated BPL signal levels were found during late 

afternoon hours during the fall and winter. 

 

Figure 5-3 depicts combinations of underground and above-ground BPL devices 

that produce increases in the noise floor of 1dB (lower curve) and 3 dB (upper curve). 

This figure is generated for the combination of ionospheric propagation and noise 

conditions (15:00 UTC during November at 30 MHz, with high-level solar activity) that 

produce the highest aggregate BPL signal relative to the local noise floor at any 

geographic point. Under these conditions, more than 1.35 million overhead BPL devices 

alone could be deployed before realizing a 1 dB increase in the noise floor at any 

geographic location. This number increases to 5.23 million overhead BPL devices for a 3 

dB aggregate noise floor increase. By reducing the number of overhead devices and 

adding underground BPL devices, the total number of deployed BPL devices can be 

greatly increased, while meeting the same levels of noise floor increase. 

 
Figure 5-3: Number of underground BPL devices compared to the number of overhead BPL devices 

required to meet specified increase in noise floor under high SSN conditions 

 

Figure 5-4 depicts numbers of overhead BPL devices compared to the number of 

underground BPL devices necessary to realize a 1 dB and 3 dB increase in the receiver 

noise floor under low solar cycle conditions. As with solar cycle maxima results, the 

fewest overall BPL devices necessary to meet the thresholds occurs when overhead BPL 

devices are used exclusively. For these conditions, approximately 916,000 overhead BPL 

devices would be required to raise the noise floor by 1 dB. By contrast, the exclusive use 

of underground BPL devices in the 1.7 to 30 MHz frequency range would allow nearly 

10 million BPL devices to be deployed before producing a 1 dB noise floor increase.
Figure 5-4: Number of underground BPL devices compared to the number of overhead BPL devices 

required to meet specified increase in noise floor under low SSN conditions 

 

5.4.2 Maps of Ionospheric Aggregation 

Figures 5-6 through 5-17 depict aggregated BPL interference-to-noise ratio 

(labeled as “Signal-to-Noise”) contour maps across CONUS for a number of BPL 

deployment cases. These maps combine the aggregate power contributions of overhead 

and underground BPL devices distributed by population throughout the United States in 

various ratios such that the maximum aggregate BPL SNR encountered at any geographic 

point produces an approximate 1 dB or 3 dB increase in the noise floor. 

 

Because of the way VOACAP produces output, only signal-to-noise ratios are 

indicated in the legends of the contour maps. To aid in interpreting Figures 5-6 through 

5-17, a sample contour map is provided in Figure 5-5. Figure 5-5 illustrates the 

translation of the values in these legends to the respective increases in the noise floor. 

The lighter shaded regions correspond to greater levels of noise floor increase due 

aggregation of BPL emissions. The peak location or locations are identified on the 

contour maps by a circular symbol having a cross inside it. 

 
 

Figure 5-5: Sample VOAAREA output map detailing the increase in the noise floor for each signalto-noise value in the map legend. 

 

 

 

Figure 5-6: Aggregation under high SSN conditions due to 24,095,730 underground devices and no 

overhead devices with maximum noise floor increase of 1 dB 

 
Figure 5-7: Aggregation under high SSN conditions due to 12,047,865 underground devices and 

760,168 overhead devices with maximum noise floor increase of 1 dB 

 

 

 

Figure 5-8: Aggregation example under high SSN conditions due to no underground devices and 

1,355,002 overhead devices with maximum noise floor increase of 1 dB 

 

 

 
Figure 5-9: Aggregation example under high SSN conditions due to 93,055,084 underground devices 

and no overhead devices with maximum noise floor increase of 3 dB 

 

 

 

Figure 5-10: Aggregation example under high SSN conditions due to 46,527,542 underground devices 

and 2,935,689 overhead devices with maximum noise floor increase of 3 dB 

 

 

 
Figure 5-11: Aggregation example under high SSN conditions due to no underground devices and 

5,232,871 overhead devices with maximum noise floor increase of 3 dB 

 

 

 

Figure 5-12: Aggregation example under low SSN conditions due to 9,816,125 underground devices 

and no overhead devices with maximum noise floor increase of 1 dB 

 

 

 
Figure 5-13: Aggregation example under low SSN conditions due to 4,908,062 underground devices 

and 458,047 overhead devices with maximum noise floor increase of 1 dB 

 

 

 

Figure 5-14: Aggregation example under low SSN conditions due to no underground devices and 

916,094 overhead devices with maximum noise floor increase of 1 dB 

 
Figure 5-15: Aggregation example under low SSN conditions due to 37,908,805 underground devices 

and no overhead devices with maximum noise floor increase of 3 dB 

 

 

 

Figure 5-16: Aggregation example under low SSN conditions due to 18,954,402 underground devices 

and 1,768,927 overhead devices with maximum noise floor increase of 3 dB 

 

 

 
 

Figure 5-17: Aggregation example under low SSN conditions due to no underground devices and 

3,537,855 overhead devices with maximum noise floor increase of 3 dB 

 

The aggregation examples of Figures 5-6 through 5-17 depict the two 

circumstances (one for low solar cycle activity and one for high) in which the fewest 

devices are needed to reach the thresholds indicated at any geographic point and across 

all conditions of time and frequency simulated. As can be seen from the figures, under 

these conditions of best propagation/lowest noise and using the assumptions developed in 

this study, more than 916,000 overhead BPL devices deployed nationwide would be 

necessary to produce increases in the noise floor of 1 dB at any geographic point—well 

above the 705,000 BPL devices expected in NTIA’s deployment model for passing 100 

percent of the urban households in the United States. Far more devices could be 

deployed without reaching either 1 dB or 3 dB thresholds if a significant percentage are 

deployed on underground power lines. 

 

In the vast majority of cases modeled (other times of day, months of the year and 

frequencies), many more devices, both underground and above ground, were required to 

produce the stipulated increases in the noise floor. 

 

5.5 SUMMARY 

NTIA modeled two power line structures and conducted comprehensive 

aggregation studies using VOAAREA propagation software to determine the potential for 

harmful interference to federal radiocommunication systems in the 1.7 to 30 MHz 

frequency range due to BPL signals propagated via the ionosphere. This analysis made 

use of several factors that differed from those used previously in the Technical Appendix 
to the NTIA Comments. These factors included BPL transmitter characteristics based 

entirely on an elaborate power line model, the use of the Part 15 measurement 

methodology in the BPL Report and Order, a more comprehensive set of ionospheric 

aggregation simulations, and the use of an underground power line model to further 

characterize aggregated interference potential. 

 

The simulation results for the deployment of Access BPL on MV overhead power 

lines operating in the 1.7 to 30 MHz band show that, for a wide scale deployment of 

overhead BPL devices (such that BPL services passes 100 percent of the urban 

households in the United States), the noise floor increase is expected to be less than 1 dB 

for the worst case propagation conditions. In reality, approximately 20 percent of the 

MV power lines are underground and many BPL systems operate in the VHF band. From 

these results, a widespread deployment of Access BPL systems in the United States is not 

expected to pose a problem for federal radiocommunication systems operating in the 1.7 

to 30 MHz band. 
 
SECTION 6 

SUMMARY OF RESULTS 

6.1 INTRODUCTION 

The Commission’s BPL Report and Order specified the rules and measurement 

guidelines for Access BPL systems. NTIA applied these rules and measurement 

guidelines in a number of analyses to evaluate their effectiveness at limiting the risk of 

interference to federal radiocommunication systems. The results of these analyses are 

summarized below. 

6.2 PHASE 2 ANALYSES 

6.2.1 Part 15 Rules and Measurement Guidelines 

In the NTIA Phase 1 Study, NTIA noted that adopting effective BPL 

measurement guidelines is critical to minimizing the risk of harmful interference to 

federal radiocommunications. NTIA further noted that emissions from Access BPL 

systems operating on overhead MV power lines were atypical of most Part 15 devices in 

that the peak field strength often occurs at heights significantly greater than 1 meter, and 

it may occur at various distances along the power line. The radiated field strength 

diminishes with distance from the source at a slower rate than that of a typical point 

source radiator. Measurements of BPL field strength are typically performed in the near 

field where the relationship between electric and magnetic field are not easily predicted. 

NTIA developed a number of power line models using the NEC software package to 

facilitate the analysis of these characteristics of BPL emissions when applying the new 

Access BPL measurement guidelines adopted by the Commission. 

 

The results of NTIA’s analysis of the characteristics of BPL emissions indicate 

that the peak field strength seen in close proximity to a BPL-energized overhead power 

line will occur at various heights, and often near the height of the power line. NTIA 

further analyzed the peak field strength using the specified measurement heights and 

found that at these measurement heights, the 80th percentile values of peak field strength 

at any height are effectively estimated by use of the Commission’s measurement 

guidelines. As noted earlier, the 80th percentile values eliminate the localized peaks that 

are unlikely to be encountered by a radio receiver randomly located in close proximity to 

an Access BPL power line. 

 

The measurement guidelines allow field strength measurements on overhead 

Access BPL power lines operating in the VHF band to be performed at a 1 meter height 

combined with application of a 5 dB height correction factor for BPL systems operating 

at or above 30 MHz. NTIA’s analysis demonstrated that the peak field strength may be 

reasonably estimated after application of this height correction factor. 

 
The FCC’s measurement guidelines require field strength measurements to be 

performed at specific points along the power line within 1 wavelength of a BPL 

source.[75] When the electric field strength was scaled to be within the Part 15 limits 

using the Access BPL measurement guidelines, NTIA’s NEC simulation results indicated 

that the percent of measurement points where the field strength exceeded the Part 15 

limits was small. 

 

NTIA evaluated the Commission’s modification of the distance extrapolation 

rules, which replaced the use of the horizontal distance between the BPL device and the 

measurement antenna with the slant range distance between them. NTIA’s NEC 

simulations in the 4 to 8 MHz frequency range exhibited somewhat slower rates of field 

strength decay with distance than would be expected by the distance extrapolation rate in 

the Part 15 rules for Access BPL systems. This difference was up to 6 dB less than the 

distance extrapolation rate. At or above 10 MHz, the simulation results show good 

agreement between the rate that field strength decays and the Part 15 distance 

extrapolation rate using the slant range distance to the Access BPL device and power 

lines. As noted earlier, the effect of the combination of direct and ground-reflected rays at 

the simulated distances becomes more pronounced at frequencies above 14 MHz. 

 

One limitation with this methodology arises when measurements are to be 

performed at distances significantly beyond the specified 10 meter measurement distance 

called for in the Commission’s measurement guidelines. In this case, the length of the 

slant range distance approaches that of the horizontal separation distance between the 

BPL device and measurement antenna, and the extrapolation rate effectively becomes the 

same as if the horizontal distance was used. The resulting extrapolation may 

overestimate the rate of field strength decay with distance and lead to the establishment 

of an operating level for the BPL device that exceeds Part 15 limits at 10 meters. It 

should also be noted that the Commission’s rules state that measurements should not be 

performed at a distance greater than 30 meters unless it can be demonstrated that 

measurements at a distance of 30 meters or less are impractical.[76]

 

Below 30 MHz, electric field strength is determined by measurement of the peak 

magnetic field strength in the horizontal plane using a loop antenna situated 1 meter 

above the ground, and application of a magnetic to electric field conversion factor. As 

these measurements are performed at a distance of 10 meters from the BPL device and 

associated power lines, they fall well within the near field region where the relationship 

between magnetic and electric field strength is not easily predicted. NTIA’s evaluation 

of the relationship between magnetic and electric field at this distance shows that use of 

the loop antenna with this conversion factor yields a reasonable approximation. NTIA 

simulations also show that, below 30 MHz, peak field strength consistently corresponded 

to the vertical electric field (horizontal magnetic field) polarization when measured at 10 

meters from the power line. At or above 30 MHz, the guidelines specify that both the 

horizontal and vertical polarizations of electric field strength are to be measured. The 

simulations performed by NTIA indicate that the specified guidelines can be used to 

represent the electric field strength levels. 

 
The measurement guidelines for Access BPL systems specify that in-situ testing 

shall be performed on three typical installations for both overhead and underground 

installations. NTIA field tests and NEC modeling of BPL power lines identified that, in 

addition to the BPL devices themselves, many features of MV power lines give rise to the 

strongest levels of radiated emissions. NTIA suggests that a variety of these features 

should exist in power lines chosen as representative sites for compliance measurement 

testing. 

6.2.2 Special Protection Provisions 

As a result of NTIA’s initial analysis, the Commission specified minimal sets of 

excluded frequency bands, exclusion zones and consultation areas needed to prevent BPL 

systems from interfering with critical federal radio operations in the 1.7 to 80 MHz 

frequency range.[77] NTIA extended the analyses for the recommended protection radii to 

include a more elaborate overhead power line model and a new underground power line 

model. NTIA analyzed the BPL emission levels that might be expected from MV 

overhead and underground power lines to determine the minimum radii of exclusion 

zones and consultation areas needed to meet the protection criteria for critical federal 

fixed and mobile radiocommunication systems, radar, and radioastronomy receivers. 

 

These provisions provide an additional measure of protection beyond that 

afforded by field strength limits and compliance measurement provisions. These special 

exclusion zones and consultation areas place only a minimal constraint on BPL 

deployment, as they impact only about 2 percent of the spectrum between 1.7 to 80 

MHz. Additional special protection provisions may be needed if, at some time in the 

future, Access BPL devices are permitted to operate outside the 1.7 to 80 MHz frequency 

range. 

6.2.3 Case Study Applying the Access BPL Measurement Guidelines 

NTIA developed a simulation of an actual overhead MV Access BPL power line 

structure to illustrate application of the BPL measurement guidelines and assess the 

potential impact on nearby land mobile systems, as well as to fixed systems at greater 

distances from the power lines. The results of these simulations are consistent with those 

from NTIA’s Phase 1 Study, and, as such, they indicate the Part 15 measurement 

procedures described in the BPL Report and Order appear to estimate adequately the 

peak field strength around the power line near ground level.[78] 

6.2.4 Aggregation of Emissions Considering Ionospheric Propagation 

In its Comments on the BPL NPRM, NTIA presented a preliminary analysis of 

the aggregation of emissions via ionospheric (i.e., “sky wave”) propagation arising from 

a wide scale deployment of Access BPL devices on MV overhead power lines.[79] At that 

time, NTIA concluded that interference via this mechanism was not a near-term issue. 

 

NTIA further developed its power line models to include an elaborate overhead 

power line model and an underground power line model. The radiation levels derived 
from these models were scaled to Part 15 limits using the recently adopted compliance 

measurement methodology. Simulations of aggregation via ionospheric propagation 

were performed for high and low SSN conditions, with frequencies ranging from 2 to 30 

MHz, and varying time of day and month of year. 

6.3 CONCLUSION 

The NTIA Phase 2 Study of Access BPL systems expanded upon the Phase 1 

Study with additional modeling results and analyses that addressed the issues that had 

been identified as requiring further study. The Phase 2 Study applied the rules and 

measurement guidelines for Access BPL systems adopted by the FCC to evaluate their 

effectiveness in minimizing the potential for harmful interference to federal 

radiocommunication systems. The results of these analyses confirm that the Part 15 

rules, measurement guidelines and special protection provisions applied to Access BPL 

deployment will limit the interference risks for federal radiocommunication systems. 

 

[1] See Potential Interference from Broadband over Power Line (BPL) Systems to Federal Government 

Radiocommunications at 1.7 – 80 MHz, NTIA Report 04-413, April 2004 (“NTIA Phase 1 Study”). In 47 

C.F.R. § 15.3(ff), an Access BPL system is defined as “[a] carrier current system installed and operated on 

an electric utility service as an unintentional radiator that sends radio frequency energy on frequencies 

between 1.705 MHz and 80 MHz over medium voltage lines or over low voltage lines to provide 

broadband communications and is located on the supply side of the utility service’s points of 

interconnection with customer premises. Access BPL does not include power line carrier systems as 

defined in Section 15.3(t) or In-House BPL systems as defined in Section 15.3(gg).” 

[2] See Amendment of Part 15 regarding new requirements and measurement guidelines for Access 

Broadband over Power Line Systems, ET Docket 04-37, Notice of Proposed Rulemaking, FCC 04-29, 

released February 23, 2004, (“BPL NPRM”); Comments of the National Telecommunications and 

Information Administration (NTIA Comments) in ET Docket No. 04-37, June 4, 2004, (available at 

www.ntia.doc.gov/ntiahome/fcc filings/2004/BPLComments_06042004.pdf) (“NTIA Comments”); Letter 

to Mr. Edmond J. Thomas, Chief, Office of Engineering and Technology, Federal Communications 

Commission, from Mr. Fredrick R. Wentland, Associate Administrator, Office of Spectrum Management, 

National Telecommunications and Information Administration, in ET Docket No. 04-37, September 13, 

2004 (“NTIA September 13, 2004 Letter”); Letter to Mr. Edmond J. Thomas, Chief, Office of Engineering 

and Technology, Federal Communications Commission, from Mr. Fredrick R. Wentland, Associate 

Administrator, Office of Spectrum Management, National Telecommunications and Information 

Administration, in ET Docket No. 04-37, September 24, 2004 (“NTIA September 24, 2004 Letter”). 

[3] See In the Matter of Amendment of Part 15 regarding new requirements and measurement guidelines for 

Access Broadband over Power Line Systems, ET Docket No. 04-37, Carrier Current Systems, including 

Broadband over Power Line Systems, ET Docket No. 03-104, Report and Order, adopted October 14, 2004 

(“BPL Report and Order”). 

[4] NEC version 4.1 software is available through Lawrence Livermore National Laboratory. URL: 

http://www.llnl.gov/IPandC/technology/software/softwaretitles/nec.php. 

[5] VOACAP is an HF statistical propagation prediction software program developed by NTIA Institute of 

Telecommunication Sciences (ITS). VOACAP is available from the NTIA Institute for 

Telecommunication Sciences, URL: http://elbert.its.bldrdoc.gov/hf.html. 
[6] See NTIA Phase 1 Study, Vol. I, at sec. 9.3.2. 

[7] Id. Vol. I, at sec. 5, 6; See also NTIA Comments, Technical Appendix, at sec. 2; NTIA September 24, 

2004 Letter. 

[8] In actual systems, all transformer impedances vary widely based upon varying loads in the system. 

However, preliminary calculations found that changing transformer impedances had little impact on the 

results. 

[9] See BPL Report and Order, at Appendix C, Measurement Guidelines ¶ 1.6. 

[10] See BPL Report and Order, Appendix C, Measurement Guidelines. 

 

[11] Below 30 MHz, the peak vertical electric field strength is calculated by scaling the peak horizontal 

magnetic field strength measured at a height of 1 meter by 377 ohms. Above 30 MHz, the peak electric 

field strength is calculated directly from the largest value in either the horizontal or vertical polarization at a 

measurement height of 1 to 4 meters. In both cases, the 80th percentile values are used as described above. 

[12] See NTIA Comments, Technical Appendix, at pp. 2-18. 

[13] See BPL Report and Order, Appendix C ¶ 2.b.2 (“Testing shall be performed at distances of 0, 1⁄4, 1⁄2, 3⁄4, 

and 1 wavelength down the line from the BPL injection point on the power line. Wavelength spacing is 

based on the mid-band frequency....”). 

[14] See 47 C.F.R. § 15.31(g)-(k). 

[15] See BPL Report and Order, at Appendix C, Measurement Guidelines ¶ 2.b.2. 

[16] Id. ¶ 2.b.4 (describing the slant range distance extrapolation methodology). 

[17] See 47 C.F.R. § 15.31(f)(1)-(2). 

[18] See NTIA BPL Phase 1 Study, Vol. II, at sec. D.3.3. 

[19] See BPL Report and Order, at Appendix C ¶ 2.b.4. 

[20] See NTIA September 24, 2004 Letter. 

[21] Note that the results at or above 30 MHz presented herein assume an antenna height of 1 meter for 

illustration purposes only. The Part 15 measurement guidelines specify that the measurements are to be 

performed at antenna heights of 1 to 4 meters. 

[22] See BPL Report and Order, at Appendix C, Measurement Guidelines ¶ 2.a. 

[23] See NTIA Phase 1 Study, Vol. I, at sec. 9.2.4; id., Vol. II, at sec. D.3.2. 

[24] See 47 C.F.R. § 15.31(f)(1)-(2). 

[25]See NTIA Phase 1 Study, Vol. I, at Table 4-9. 

[26] See NTIA Comments, at sec. III. 

[27] See BPL Report and Order, at Appendix B (amending Part 15 to add a new Subpart G). 

[28] See 47 C.F.R. § 15.615(f). 

[29] NTIA Phase 1 Study, Vol. I, at sec. 5.3.6; NTIA Comments, at Technical Appendix sec. 2.3. 

[30] See NTIA Phase 1 Study, Vol. II, at Appendix C. 

[31] Manual of Regulations and Procedures for Federal Radio Frequency Managers, United States 

Department of Commerce, National Telecommunications and Information Administration, Washington, 

D.C., January 2004 Revision. 

[32] In this description of noise floor increase, the term “I” is the interfering signal power at the receiver site 

associated with radiated BPL emissions, and the term “N” is the noise power that would be present at the 

receiver site in the absence of BPL emissions. The interference-plus-noise-to-noise [(I+N)/N] is used to 

determine the noise floor increase. 

[33] For this analysis, the protection requirement for sensitive over-the-horizon (OTH) radar receivers was 

assumed to be the same as that used for the Very Large Array (VLA) radio astronomy receiver. Like radio 

astronomy receivers, radar receivers employ correlation techniques that enable reception of signals weaker 

than noise. The radioastronomy protection criterion is specified in Recommendation ITU-R RA.769-2, 

Table 1. 
[34] See Recommendation ITU-R RA.769-2, Table 1 for the protection criteria in the 73.0-74.6 MHz 

frequency band. This frequency band is used at the Very Large Array (VLA) radioastronomy facility near 

Socorro, New Mexico. 

[35] The Commission’s rules specify an electric field strength limit of 30 μV/m at a horizontal distance of 

30 meters for radiated emissions in the 1.705 to 30 MHz band. 47 C.F.R. § 15.209(a). 

[36] The modeled measurement heights ranged from 1 to 4 meters, in 0.5 meter increments. 

[37] See NTIA Phase 1 Study, Vol. I, at Table 6-2. 

[38] TCI Model 527, Super High Gain Log-Periodic Antenna data sheet. 

[39] Noise power levels were determined using the NOISEDAT computer program, assuming a 

representative protected receiver location. NOISEDAT is available from the ITU website, url: 

http://www.itu.int/ITU-R/software/study-groups/rsg3/databanks/ionosph/index.html. 

[40] A Guide to the Use of the ITS Irregular Terrain Model in the Area Prediction Mode, NTIA Report 82-

100 (April 1982). 

[41] See NTIA September 13, 2004 Letter, at Annex 1, sec. 2.2. 

[42] BWmeas is 9 kHz for frequencies below 30 MHz, and 120 kHz for frequencies between 30 MHz and 80 

MHz. 

[43] See NTIA Phase 1 Study, Volume II, at pp. D-38 and D-39. The field measurements from the BPL 

Phase 1 Study indicated that 6 dB is an appropriate factor to convert between peak and RMS field strength 

for Access BPL systems. 

[44] See NTIA September 13, 2004 Letter, at Annex 1, sec. 2.2. 

[45] The frequency 25 MHz was chosen for this analysis due to simulation results showing that the power 

line may be a more efficient radiator at or near this frequency. See NTIA September 13, 2004 Letter, at 

14. 

[46] See Recommendation ITU-R RA.769-2, Table 1 for the protection criteria in the 73.0-74.6 MHz 

frequency band. This frequency band is used at the VLA radioastronomy facility near Socorro, New 

Mexico. 

[47] See NTIA September 13, 2004 Letter, at Annex 1, sec. 2.2. 

[48] The ITM program may yield inaccurate results due to ground clutter when an antenna height of less 

than 1 meter is used. When using a 0.2 meter antenna height, as was done for the underground BPL 

analysis, the results obtained by ITM can underestimate the path loss. In an actual underground BPL 

deployment, the values of path loss are expected to be greater, and the PFD at the boundary of the 

exclusion zones should be below the protection levels assumed in this analysis. 

[49] See NTIA September 13, 2004 Letter, at Annex 1, sec. 3.1. 

[50] See BPL Report and Order, at 71. 

[51] Letter to Mr. Edmond J. Thomas, Chief, Office of Engineering and Technology, Federal 

Communications Commission, from Mr. Fredrick R. Wentland, Associate Administrator, Office of 

Spectrum Management, National Telecommunications and Information Administration in ET Docket No. 

04-37, March 1, 2005 (“NTIA March 1, 2005 Letter”). For Access BPL on overhead MV power lines, 

NTIA requested a 65 km radius BPL exclusion zone centered at the coordinates of the VLA 

radioastronomy facility. This radius equates to 29 km beyond the 36 km radius of the antenna array. NTIA 

also requested a 47 km radius exclusion zone centered at the coordinates of the VLA for Access BPL 

systems operating on underground MV or overhead low voltage (LV) power lines. 

[52] During its initial study of BPL systems, NTIA measured peak power emissions in close proximity to a 

transformer vault containing a BPL device. Most attempts to measure the peak power emanating from the 

underground BPL system resulted in levels below the minimum sensitivity of NTIA’s Radio Spectrum 

Measurement System (RSMS-4). See NTIA Phase 1 Study, at Volume II, p. D-33. 

[53] The Commission’s rules specify an electric field strength limit of 30 μV/m at a horizontal distance of 

30 meters for radiated emissions in the 1.705 to 30 MHz band. 47 C.F.R. § 15.209(a). 
[54] NOISEDAT is available from the ITU Website, URL: http://www.itu.int/ITU-R/software/studygroups/rsg3/databanks/ionosph/index.html. 

[55] Noise floor increases of 3, 10, 20, 30, 40 and 50 dB were analyzed. This allows comparison with the 

results presented in the NTIA Phase 1 Study, Vol. I, at Table 6-1. 

[56] The choice of quasi-peak-to-RMS measurement factor was based on the measurement data from the 

NTIA Phase 1 Study, which indicated that the BPL signal power measured using a quasi-peak detector 

typically exceeded the level measured using an average detector by 0 – 5 dB. See NTIA Phase 1 Study, 

Volume II, at sec. D.3.4. 

[57] See NTIA September 13, 2004 Letter, at Annex 1, sec. 2.2. 

[58] See NTIA Phase 1 Study, Vol. I, at pp. 6-11; NTIA September 13, 2004 Letter, at Annex 1. 

[59] See NTIA Phase 1 Study, Vol. I, at sec. 5.2.2. 

[60] See NTIA Comments, at Technical Appendix, sec. 4. 

[61] Id. See also NTIA Phase 1 Study, Vol. I, at sec. 5.4. 

[62] See NTIA Comments, at Technical Appendix, sec. 2.2. 

[63] See BPL Report and Order, at Appendix C, Measurement Guidelines ¶ 2.b. 

[64] See BPL Report and Order, at Appendix C, Measurement Guidelines ¶ 2.b. 

[65] See BPL Report and Order, at Appendix C, Measurement Guidelines ¶ 2.b.2, for a description of 

additional measurements that may be required if the mid-band frequency of the BPL signal is two or more 

times greater than the lowest BPL signal injected onto the power line. 

[66] Id.

[67] See NTIA Comments, at Technical Appendix, sec. 4.2. See also County and City Data Book: 2000, 

U.S. Census Bureau, National Data Summary File 1, Table P-15. 

[68] In this report, (I+N)/N is also referred to as “noise floor increase.” 

[69] VOAAREA allows one to set the length of the vertical antenna either to a fixed value in meters or to 

allow it to vary with frequency. In this analysis, it was assumed that a receiver subject to potential 

interference at any given frequency would make use of an antenna designed for that frequency; therefore, 

the antenna in this case was set to quarter-wave length for each frequency (e.g., 7.5 meters at 10 MHz). 

VOACAP automatically adjusts this length such that the receive pattern stays the same regardless of 

frequency. As is appropriate for a monopole antenna, the maximum gain for the antenna at any height was 

set to 3 dB above that of a dipole. 

[70] Noise level used in this analysis is based on Recommendation ITU-R P.372-8, "Radio Noise" 

implemented in VOACAP/VOAAREA. 

[71] See ITU-R Chairman's report on the meeting of Working Party 1C, Geneva, 11-15 October 2004, 

document #54, Annex 2, “Noise Measurements.” 

[72] See NTIA Comments, at Technical Appendix, sec. 4. 

[73] The choice of quasi-peak-to-RMS conversion factor was based on the measurement data from the NTIA 

Phase 1 Study, which indicated that the BPL signal power measured using a quasi-peak detector typically 

exceeded the level measured using an average detector by 0 – 5 dB. See NTIA Phase 1 Study, at Volume 

II, sec. D.3.4. 

[74] As previously noted in Section 3.2.3, the term “I” refers to the interfering signal power associated with 

radiated BPL emissions. 

[75] For wide bandwidth BPL signals, where the center frequency exceeds the lowest in-band frequency by 

at least a factor of two, additional measurements beyond 1 wavelength are required. See BPL Report and 

Order, at Appendix C, Measurement Guidelines ¶ 2.b.2. 

[76] See 47 C.F.R. § 15.31(f)(1) for operation at or above 30 MHz. Between 1.705 MHz and 30 MHz, 47 

C.F.R. § 15.209(a) defines the field strength limit at a measurement distance of 30 meters. 
[77] See NTIA September 13, 2004 Letter, at Annex 1. 

[78] See NTIA Phase 1 Study, Vol. I, at pp. 6-11. 

[79] See NTIA Comments, at Technical Appendix, at sec. 4. 
 NTIA Report 08-450 

POTENTIAL INTERFERENCE FROM 

BROADBAND OVER POWER LINE (BPL) 

SYSTEMS TO FEDERAL GOVERNMENT 

RADIOCOMMUNICATION SYSTEMS 

AT 1.7 - 80 MHz 

Phase 2 Study 

VOLUME II 

technical report 

U.S. DEPARTMENT OF COMMERCE y National Telecommunications and Information Administration 
 
 

NTIA Report 08-450 

POTENTIAL INTERFERENCE FROM BROADBAND OVER 

POWER LINE (BPL) SYSTEMS TO FEDERAL GOVERNMENT 

RADIOCOMMUNICATION SYSTEMS AT 1.7 - 80 MHz 

Phase 2 Study 

VOLUME II 

James C. Richards 

Jonathan V. Williams 

U.S. Department of Commerce 

Carlos M. Gutierrez, Secretary 

John M. R. Kneuer, Assistant Secretary 

for Communications and Information 

October 2007 
 
iii 

 

 VOLUME II 

TABLE OF CONTENTS 

 

TECHNICAL APPENDICES

 

TABLE OF CONTENTS ...................................................................... iii 

GLOSSARY .................................................................................... iv 

 

APPENDIX A ANTENNA MEASUREMENT HEIGHT 

 A.1 Introduction ............................................................... A-1 

 A.2 Height of Peak Field Strength .......................................... A-1 

 A.3 Compliance Measurement Height for Operation Between 1.7 – 

30 MHz ................................................................... A-10 

 A.4 Compliance Measurement Height for Operation at 30 MHz and 

Above ..................................................................... A-53 

 A.5 Height Correction Factor Above 30 MHz .......................... A-62 

 

APPENDIX B MEASUREMENT DISTANCE ALONG THE POWER LINE 

 B.1 Introduction .............................................................. B-1 

 B.2 Simulation Results ...................................................... B-1 

 

APPENDIX C MEASUREMENT DISTANCE EXTRAPOLATION 

 C.1 Introduction ............................................................... C-1 

 C.2 BPL Field Strength Simulation Results ............................... C-1 

 C.2.1 Extrapolated Field Strength Levels Meeting the Part 15 Limits ... C-1 

 C.2.2 Simulation Results ....................................................... C-2 

 

APPENDIX D SPECIAL PROTECTION PROVISIONS 

 D.1 Excluded Frequency Bands ............................................. D-1 

 D.2 Exclusion Zones .......................................................... D-2 

 D.2.1 Coast Stations ............................................................ D-2 

 D.2.2 Radioastronomy Observatories ........................................ D-5 

 D.3 Consultation Areas ...................................................... D-7 

 
iv 

 

 GLOSSARY 

 

 

AWG American Wire Gauge 

BPL Broadband over Power Line(s) 

BW Bandwidth 

CISPR International Special Committee on Radio Interference 

CONUS Continental United States 

COTHEN Customs Over The Horizon Enforcement Network 

dB Decibel 

dBi Decibel referenced to an isotropic radiator 

dBm Decibel referenced to 1 milliwatt 

dBμV Decibel referenced to 1 microvolt 

dBW Decibels referenced to 1 Watt 

E Electric Field Strength 

EMC Electromagnetic Compatibility 

EUT Equipment Under Test 

FCC Federal Communications Commission 

G Gain 

GHz Gigahertz 

H Magnetic Field Strength 

HF High Frequency 

Hz Hertz 

I Interference Power 

ICAO International Civil Aviation Organization 

IRAC Interdepartment Radio Advisory Committee 

ITM Irregular Terrain Model 

ITS Institute for Telecommunication Sciences 

ITU International Telecommunication Union 

ITU-R International Telecommunication Union Radiocommunication Sector 

kHz Kilohertz 

km Kilometer 

LV Low Voltage 

m Meter 

MHz Megahertz 

mm millimeter 

mS Siemens/meter 

ms Millisecond 

MV Medium Voltage 

N Noise Power 

NEC Numerical Electromagnetic Code 

NOI Notice of Inquiry 

NPRM Notice of Proposed Rulemaking 

NTIA National Telecommunications and Information Administration 

OR Off-Route 
v 

 

OTH Over the Horizon 

PFD Power Flux Density 

PLC Power Line Communications 

PLT Power Line Telecommunications 

R Route 

RF Radio Frequency 

RMS Root Mean Square 

RSMS Radio Spectrum Measurement System 

S Signal Power 

SNR Signal-to-Noise Ratio 

SSB Single Sideband 

SSN Smoothed Sunspot Number 

URD Underground Residential Distribution 

US&P United States and Possessions 

UTC Universal Coordinated Time 

VHF Very High Frequency 

VLA Very Large Array 

VOA Voice of America 

VOACAP Voice of America Coverage Analysis Program 

W Watt 

μA Microampere 

μV Microvolt 
vi 

 
A-1 

APPENDIX A 

MEASUREMENT ANTENNA HEIGHT 

A.1 INTRODUCTION 

Section A.2 describes NTIA’s Numerical Electromagnetics Code (NEC) 

simulation results showing the height where the peak field strength is expected in close 

proximity to an Access Broadband over Power Line (BPL) system operating on overhead 

Medium Voltage (MV) power lines. Section A.3 shows the effectiveness of the 1 meter 

measurement height in estimating the peak field strength at frequencies between 1.7 and 

30 MHz. Section A.4 provides results from simulations performed in the 30 – 50 MHz 

range, using the 1 to 4 meter measurement height range defined in the compliance 

measurement guidelines for Access BPL systems operating above 30 MHz. In Section 

A.5, the optional 5-dB height correction factor for measurements at a 1 meter height is 

compared to the use of the 1 to 4 meter measurement height for the various power line 

simulations at frequencies above 30 MHz. 

A.2 HEIGHT OF PEAK FIELD STRENGTH 

Figures A-1 through A-18 show the heights where the peak electric field strength 

occurred over the frequency range of 2 to 50 MHz for the NEC power line models 

described in Section 2.2. The height of the modeled power lines was 12 meters. These 

results assume field strength values are calculated at a horizontal distance of 10 meters. 

Figure A-1: Height corresponding to peak electric field strength as a function of frequency 

tri36

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-2 

Figure A-2: Height corresponding to peak electric field strength as a function of frequency 

Figure A-3: Height corresponding to peak electric field strength as a function of frequency 

tri36n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

tri310

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-3 

Figure A-4: Height corresponding to peak electric field strength as a function of frequency 

Figure A-5: Height corresponding to peak electric field strength as a function of frequency 

tri310n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

ver36

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-4 

Figure A-6: Height corresponding to peak electric field strength as a function of frequency 

Figure A-7: Height corresponding to peak electric field strength as a function of frequency 

ver36n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

ver310

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-5 

Figure A-8: Height corresponding to peak electric field strength as a function of frequency 

Figure A-9: Height corresponding to peak electric field strength as a function of frequency 

tri26

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

ver310n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-6 

Figure A-10: Height corresponding to peak electric field strength as a function of frequency 

Figure A-11: Height corresponding to peak electric field strength as a function of frequency

tri26n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

tri210

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-7 

Figure A-12: Height corresponding to peak electric field strength as a function of frequency

Figure A-13: Height corresponding to peak electric field strength as a function of frequency 

tri210n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

ver26

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-8 

Figure A-14: Height corresponding to peak electric field strength as a function of frequency

Figure A-15: Height corresponding to peak electric field strength as a function of frequency

ver26n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

ver210

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-9 

Figure A-16: Height corresponding to peak electric field strength as a function of frequency

Figure A-17: Height corresponding to peak electric field strength as a function of frequency 

ver1

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height

ver210n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-10 

Figure A-18: Height corresponding to peak electric field strength as a function of frequency 

A.3 COMPLIANCE MEASUREMENT HEIGHT FOR 

OPERATION BETWEEN 1.7 - 30 MHz 

The Federal Communication Commission (Commission or FCC) Part 15 

measurement guidelines specify that below 30 MHz, measurements are to be made with 

the antenna positioned at a height of 1 meter. In Section A.2, the height corresponding to 

the peak field strength was often located well above the 1 meter measurement height. 

The following plots show a comparison between the peak field strength determined from 

the measurement guidelines and the 80th percentile of peak electric field strength at any 

height along the length of the power line. The 80th percentile values eliminate the 

localized peaks that are unlikely to be encountered by a radio receiver randomly located 

in close proximity to an Access BPL power line.1

 The plots are shown for a number of 

NEC power line models at frequencies from 2 to 28 MHz. 

 

1 See NTIA Comments, at Technical Appendix, pp. 2-18. 

ver1n

0

2

4

6

8

10

12

14

16

18

20

2 6 10 14 18 22 26 30 34 38 42 46 50

Frequency (MHz)

Height (m)

E(peak) Height

Power Line Height
A-11 

2 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 2 MHz

Figure A-19: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 2 MHz

Figure A-20: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-12 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 2 MHz

Figure A-21: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 2 MHz

Figure A-22: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-13 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 2 MHz

Figure A-23: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 2 MHz

Figure A-24: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-14 

4 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 4 MHz

Figure A-25: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 4 MHz

Figure A-26: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-15 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 4MHz

Figure A-27: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 4 MHz

Figure A-28: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-16 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 4 MHz

Figure A-29: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 4 MHz

Figure A-30: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-17 

6 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 6 MHz

Figure A-31: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 6 MHz

Figure A-32: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-18 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 6 MHz

Figure A-33: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 6 MHz

Figure A-34: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-19 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 6 MHz

Figure A-35: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 6 MHz

Figure A-36: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-20 

8 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 8 MHz

Figure A-37: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 8 MHz

Figure A-38: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-21 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 8 MHz

Figure A-39: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 8 MHz

Figure A-40: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-22 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 8 MHz

Figure A-41: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 8 MHz

Figure A-42: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-23 

10 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 10 MHz

Figure A-43: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 10 MHz

Figure A-44: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-24 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 10 MHz

Figure A-45: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 10 MHz

Figure A-46: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-25 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 10 MHz

Figure A-47: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 10 MHz

Figure A-48: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-26 

12 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 12 MHz

Figure A-49: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 12 MHz

Figure A-50: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-27 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 12 MHz

Figure A-51: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 12 MHz

Figure A-52: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-28 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 12 MHz

Figure A-53: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 12 MHz

Figure A-54: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-29 

14 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 14 MHz

Figure A-55: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 14 MHz

Figure A-56: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-30 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 14 MHz

Figure A-57: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 14 MHz

Figure A-58: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-31 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 14 MHz

Figure A-59: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 14 MHz

Figure A-60: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-32 

16 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 16 MHz

Figure A-61: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 16 MHz

Figure A-62: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-33 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 16 MHz

Figure A-63: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 16 MHz

Figure A-64: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-34 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 16 MHz

Figure A-65: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 16 MHz

Figure A-66: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-35 

18 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 18 MHz

Figure A-67: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 18 MHz

Figure A-68: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-36 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 18 MHz

Figure A-69: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 18 MHz

Figure A-70: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-37 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 18 MHz

Figure A-71: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 18 MHz

Figure A-72: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-38 

20 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 20 MHz

Figure A-73: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 20 MHz

Figure A-74: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-39 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 20 MHz

Figure A-75: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 20 MHz

Figure A-76: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-40 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 20 MHz

Figure A-77: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 20 MHz

Figure A-78: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-41 

22 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 22 MHz

Figure A-79: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 22 MHz

Figure A-80: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-42 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 22 MHz

Figure A-81: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 22 MHz

Figure A-82: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-43 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 22 MHz

Figure A-83: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 22 MHz

Figure A-84: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-44 

24 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 24 MHz

Figure A-85: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 24 MHz

Figure A-86: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-45 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 24 MHz

Figure A-87: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 24 MHz

Figure A-88: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-46 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile - E max (1 m) (dB)

ver26n at 24 MHz

Figure A-89: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 24 MHz

Figure A-90: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-47 

26 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 26 MHz

Figure A-91: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 26 MHz

Figure A-92: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-48 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 26 MHz

Figure A-93: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 26 MHz

Figure A-94: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-49 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 26 MHz

Figure A-95: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 26 MHz

Figure A-96: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-50 

28 MHz Plots

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36 at 28 MHz

Figure A-97: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri36n at 28 MHz

Figure A-98: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-51 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

tri26n at 28 MHz

Figure A-99: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver1n at 28 MHz

Figure A-100: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-52 

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver26n at 28 MHz

Figure A-101: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height

-20

-15

-10

-5

0

5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1 m) (dB)

ver36n at 28 MHz

Figure A-102: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at a 1 meter measurement height
A-53 

A.4 COMPLIANCE MEASUREMENT HEIGHT FOR 

OPERATION AT 30 MHz AND ABOVE 

The Commission’s Part 15 measurement guidelines specify that at or above 30 

MHz, measurements are to be made with the antenna positioned at a height ranging from 

1 to 4 meters. The electric field strength should be measured in both the horizontal and 

vertical planes. The following plots show a comparison between the peak field strength 

determined from applying the measurement guidelines to the power line simulations to 

compute the 80th percentile of peak field strength at any height along the length of the 

power line. The rationale for use of 80th percentile values was previously addressed in 

Section A.3. The plots are shown for a number of NEC power line models at the 

frequencies of 30, 40 and 50 MHz. 

30 MHz Plots

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri36 at 30 MHz

Figure A-103: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-54 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri36n at 30 MHz

Figure A-104: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri26n at 30 MHz

Figure A-105: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-55 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver1n at 30 MHz

Figure A-106: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver26n at 30 MHz

Figure A-107: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-56 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver36n at 30 MHz

Figure A-108: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

40 MHz Plots

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri36 at 40 MHz

Figure A-109: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-57 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri36n at 40 MHz

Figure A-110: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri26n at 40 MHz

Figure A-111: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-58 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver1n at 40 MHz

Figure A-112: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver26n at 40 MHz

Figure A-113: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-59 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver36n at 40 MHz

Figure A-114: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

50 MHz Plots

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri36 at 50 MHz

Figure A-115: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-60 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri36n at 50 MHz

Figure A-116: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

tri26n at 50 MHz

Figure A-117: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-61 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver1n at 50 MHz

Figure A-118: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver26n at 50 MHz

Figure A-119: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height
A-62 

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (1-4 m) (dB)

ver36n at 50 MHz

Figure A-120: 80th percentile of peak electric field strength along the power line relative to the peak 

electric field strength at the 1 to 4 meter measurement height 

A.5 HEIGHT CORRECTION FACTOR ABOVE 30 MHz 

Above 30 MHz, the option to perform compliance measurements at a 1 meter 

measurement height coupled with a 5 dB height correction factor provides a much 

simpler measurement approach than to perform measurements over a 1 to 4 meter range 

of measurement antenna heights. Figures A-121 through A-138 show the comparison 

between use of a 1 to 4 meter measurement height and the optional use of a 1 meter 

measurement height. 

The results shown in these figures indicate that use of the optional 1 meter 

measurement height tends to underestimate the peak electric field strength by 2.5 to 7.5 

dB. Thus, the use of the optional 1 meter measurement height coupled with a 5 dB 

correction factor will, in general, provide similar results to measurements performed 

using a 1 to 4 meter measurement height. 
A-63 

30 MHz Plots

tri36 at 30 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height ) (dB)

1 meter

1-4 meters

A-121: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

tri36n at 30 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height ) (dB)

1 meter

1-4 meters

A-122: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-64 

tri26n at 30 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height ) (dB)

1 meter

1-4 meters

A-123: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

ver1n at 30 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height ) (dB)

1 meter

1-4 meters

A-124: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-65 

ver26n at 30 MHz

-7.5

-5.0

-2.5

0.0

2.5

5.0

7.5

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height ) (dB)

1 meter

1-4 meters

A-125: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

ver36n at 30 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height ) (dB)

1 meter

1-4 meters

A-126: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-66 

40 MHz Plots

tri36 at 40 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-127: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

tri36n at 40 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-128: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-67 

tri26n at 40 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-129: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

ver1n at 40 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-130: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-68 

ver26n at 40 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-131: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

ver36n at 40 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-132: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-69 

50 MHz Plots

tri36 at 50 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-133: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

tri36n at 50 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-134: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-70 

tri26n at 50 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-135: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

ver1n at 50 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-136: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-71 

ver26n at 50 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-137: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters

ver36n at 50 MHz

-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

0 5 10 15 20

Measurement Height (m)

80th %-ile E max - Emax (compliance test 

height) (dB)

1 meter

1-4 meters

A-138: Comparison of electric field strength as a function of measurement height, if compliance 

measurements were performed at heights of 1 meter, or at 1 to 4 meters
A-72 
B-1 

APPENDIX B 

MEASUREMENT DISTANCE ALONG THE POWER LINE 

B.1 INTRODUCTION 

 As noted in the NTIA Phase 1 Study, compliance measurement testing 

commissioned by BPL equipment vendors and service providers has generally focused on 

radiated emissions measured on radials from the BPL device under test. However, FCC 

rules state that Part 15 devices and all attached wiring should be considered when 

measuring radiated emissions.2

 The Commission’s BPL measurement guidelines specify 

the locations along the power line away from a BPL device where field strength 

measurements are to be taken.3

 This Appendix provides NTIA’s results from evaluating 

the field strength along the length of the power line and comparing this to the field 

strength levels at the prescribed measurement locations.

B.2 SIMULATION RESULTS 

Figures B-1 through B-84 show the electric field strength level along the power 

line for a variety of simulated power line configurations, and over the frequency range of 

2 to 28 MHz. Each figure includes the Part 15 radiated emissions limit extrapolated to a 

measurement distance of 10 meters assuming the power line height is 12 meters.4 In 

addition, these figures show the measurement points specified in the measurement 

guidelines. The peak value of these points was used to scale the signal source level so 

that the power line model satisfies the Part 15 limit, as extrapolate to the 10 meter 

measurement distance. Electric field strength values were determined from NEC 

magnetic field strength simulations of the power line models using the methodology 

described in Section 2.2. 

 

2 See 47 C.F.R. §15.31(g)-(k). 

3 See BPL Report and Order, at Appendix C ¶ 2.b.2 (“Testing shall be performed at distances of 0, 1⁄4, 1⁄2, 3⁄4, 

and 1 wavelength down the line from the BPL injection point on the power line. Wavelength spacing is 

based on the mid-band frequency...”). 

4 Id. ¶ 2.b.4 (describing the slant range distance extrapolation methodology). 
B-2 

2 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 2 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-1: Vertical electric field strength along power line for tri36 topology 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 2 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-2: Vertical electric field strength along power line for tri36n topology
B-3 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 2 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-3: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 2 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-4: Vertical electric field strength along power line for ver1n topology
B-4 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 2 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-5: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 2 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-6: Vertical electric field strength along power line for ver36n topology
B-5 

4 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 4 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-7: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 4 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-8: Vertical electric field strength along power line for tri36n topology
B-6 

10

15

20

25

30

35

40

45

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 4 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-9: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 4 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-10: Vertical electric field strength along power line for ver1n topology
B-7 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 4 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-11: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 4 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-12: Vertical electric field strength along power line for ver36n topology
B-8 

6 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 6 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-13: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 6 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-14: Vertical electric field strength along power line for tri36n topology
B-9 

10

15

20

25

30

35

40

45

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 6 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-15: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 6 MHz

Limit extrapolated to 10 m

Measurment points

Figure B-16: Vertical electric field strength along power line for ver1n topology
B-10 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 6 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-17: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 6 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-18: Vertical electric field strength along power line for ver36n topology
B-11 

8 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 8 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-19: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 8 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-20: Vertical electric field strength along power line for tri36n topology
B-12 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tr26n at 8 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-21: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 8 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-22: Vertical electric field strength along power line for ver1n topology
B-13 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 8 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-23: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 8 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-24: Vertical electric field strength along power line for ver36n topology
B-14 

10 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 10 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-25: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 10 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-26: Vertical electric field strength along power line for tri36n topology
B-15 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 10 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-27: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 10 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-28: Vertical electric field strength along power line for ver1n topology
B-16 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 10 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-29: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 10 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-30: Vertical electric field strength along power line for ver36n topology
B-17 

12 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 12 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-31: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 12 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-32: Vertical electric field strength along power line for tri36n topology
B-18 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 12 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-33: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 12 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-34: Vertical electric field strength along power line for ver1n topology
B-19 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 12 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-35: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 12 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-36: Vertical electric field strength along power line for ver36n topology
B-20 

14 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 14 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-37: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 14 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-38: Vertical electric field strength along power line for tri36n topology
B-21 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 14 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-39: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 14 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-40: Vertical electric field strength along power line for ver1n topology
B-22 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 14 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-41: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 14 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-42: Vertical electric field strength along power line for ver36n topology
B-23 

16 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 16 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-43: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 16 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-44: Vertical electric field strength along power line for tri36n topology
B-24 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 16 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-45: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 16 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-46: Vertical electric field strength along power line for ver1n topology
B-25 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 16 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-47: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 16 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-48: Vertical electric field strength along power line for ver36n topology
B-26 

18 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 18 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-49: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 18 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-50: Vertical electric field strength along power line for tri36n topology
B-27 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 18 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-51: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 18 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-52: Vertical electric field strength along power line for ver1n topology
B-28 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 18 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-53: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 18 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-54: Vertical electric field strength along power line for ver3n topology
B-29 

20 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 20 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-55: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 20 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-56: Vertical electric field strength along power line for tri36n topology
B-30 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 20 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-57: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 20 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-58: Vertical electric field strength along power line for ver1n topology
B-31 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 20 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-59: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 20 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-60: Vertical electric field strength along power line for ver36n topology
B-32 

22 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 22 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-61: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 22 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-62: Vertical electric field strength along power line for tri36n topology
B-33 

0

5

10

15

20

25

30

35

40

45

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 22 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-63: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 22 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-64: Vertical electric field strength along power line for ver1n topology
B-34 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 22 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-65: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 22 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-66: Vertical electric field strength along power line for ver36n topology
B-35 

24 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 24 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-67: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 24 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-68: Vertical electric field strength along power line for tri36n topology
B-36 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 24 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-69: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 24 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-70: Vertical electric field strength along power line for ver1n topology
B-37 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 24 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-71: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 24 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-72: Vertical electric field strength along power line for ver36n topology
B-38 

26 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 26 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-73: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 26 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-74: Vertical electric field strength along power line for tri36n topology
B-39 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 26 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-75: Vertical electric field strength along power line for tri26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 26 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-76: Vertical electric field strength along power line for ver1n topology
B-40 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 26 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-77: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 26 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-78: Vertical electric field strength along power line for ver36n topology
B-41 

28 MHz Plots

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36 at 28 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-79: Vertical electric field strength along power line for tri36 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri36n at 28 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-80: Vertical electric field strength along power line for tri36n topology
B-42 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

tri26n at 28 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-81: Vertical electric field strength along power line for tri26 topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver1n at 28 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-82: Vertical electric field strength along power line for ver1n topology
B-43 

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver26n at 28 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-83: Vertical electric field strength along power line for ver26n topology

10

15

20

25

30

35

40

45

50

-200 -150 -100 -50 0 50 100 150 200

Distance along power line away from BPL 

device (m)

Electric Field Strength (dBuV/m)

ver36n at 28 MHz

Limit extrapolated to 10 m

Measurement points

Figure B-84: Vertical electric field strength along power line for ver36n topology 
B-44 
C-1 

APPENDIX C 

MEASUREMENT DISTANCE EXTRAPOLATION 

C.1 INTRODUCTION 

The distance extrapolation calculation based on use of the slant path distance from 

the BPL device and power lines under test and the measurement antenna was discussed in 

Section 2.5 of the report. Some of the resulting plots from NTIA’s NEC power line 

model simulations were reported in that section. The remaining plots are included in this 

appendix. 

C.2 BPL FIELD STRENGTH SIMULATION RESULTS 

C.2.1 Extrapolated Field Strength Levels Meeting the Part 15 Limits 

Figure C-1 shows the extrapolated electric field strength levels that satisfy the 

Part 15 limits using slant range distance extrapolation, assuming a power line height of 

12 meters. The simulated measurement antenna height is assumed to be 1 meter. 

15

20

25

30

35

40

45

50

55

0 5 10 15 20 25 30

Horizontal Distance (m)

Electric Field Strength (dB μV/m)

Below 30 MHz

30 MHz and Above

Figure C.1 - Extrapolated field strength levels meeting Part 15 emissions limits based on slant-range 

distance to the BPL device under test 
C-2 

C.2.2 Simulation Results 

Figures C-2 through C-15 shows the simulated electric field strength moving 

away from the power line for a number of power line structures that were previously 

defined in Section 2.2 of the BPL Phase 2 Study. The extrapolated field strength levels 

meeting the Part 15 emissions limit below 30 MHz are displayed on each figure for 

comparison. The simulations determined the vertical electric field strength from the 

horizontal magnetic field strength using the methodology for compliance testing in the 

Part 15 rules for Access BPL and assuming the electric field strength is related to the 

magnetic field strength by η = 377 ohms (Ω). The peak field strength value was chosen 

from among the values calculated at points along the line, as defined in the measurement 

guidelines, at a distance of 10 meters away from the line. The plots of field strength 

relative to distance are taken from this corresponding location for each case. 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-2: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 2 MHz
C-3 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

MaxElectric field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-3: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 4 MHz

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-4: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 6 MHz
C-4 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-5: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 8 MHz

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-6: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 10 MHz
C-5 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-7: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 12 MHz

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-8: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 14 MHz
C-6 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-9: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 16 MHz

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-10: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 18 MHz
C-7 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-11: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 20 MHz 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-12: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 22 MHz 
C-8 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-13: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 24 MHz 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-14: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 26 MHz 
C-9 

20

25

30

35

40

45

50

55

60

0 5 10 15 20 25 30

Horizontal Distance (m)

Max Electric Field Strength (dBuV/m)

tri36n

ver1n

ver26n

ver36n

tri26n

tri36

< 30 MHz Limit

Figure C-15: Electric field strength compared to emissions limit based on slant-range extrapolation 

for various power line models – 28 MHz 
C-10 
D-1 

APPENDIX D 

SPECIAL PROTECTION PROVISIONS 

D.1 EXCLUDED FREQUENCY BANDS 

As adopted in the BPL Report and Order, Access BPL emissions from overhead 

MV power lines are excluded from aeronautical (R) mobile allocations in the 1.7 – 30 

MHz frequency range and the 74.8 – 75.2 MHz aeronautical radionavigation band, as 

delineated in Table D-1. Otherwise, with mature deployments of BPL devices: (1) 

reception of aeronautical safety communications by aeronautical (land or “base”) stations 

would be endangered; (2) reception of aeronautical safety communications by aircraft 

would be endangered; and (3) at some aeronautical station or aircraft locations, emissions 

from In-House BPL devices at these frequencies will increase receiver noise levels such 

that additional interfering signals from Access BPL devices cannot be risked. This 

exclusion amounts to less than 2.18 percent of national spectrum resource between 1.7 

MHz and 80 MHz. 

Table D-1: Bands in Which Access BPL Emissions Are Prohibited 

Frequency Band Total Spectrum (kHz) 

2,850 – 3,025 kHz 175 

3,400 – 3,500 kHz 100 

4,650 – 4,700 kHz 50 

5,450 – 5,680 kHz 230 

6,525 – 6,685 kHz 160 

8,815 – 8,965 kHz 150 

10,005 – 10,100 kHz 95 

11,275 – 11,400 kHz 100 

13,260 – 13,360 kHz 100 

17,900 – 17,970 kHz 70 

21,924 – 22,000 kHz 76 

74.8 – 75.2 MHz 400 

TOTAL BANDWIDTH 1,706 

U.S. AREA FACTOR 1.0 

PORTION OF NATIONAL SPECTRUM 

RESOURCE AT 1.7 – 80 MHz < 2.18% (area factor x bandwidth factor) 

D.2 EXCLUSION ZONES 

D.2.1 Coast Stations 

The analytical results of Section 3.3.1 lead to a requirement to define exclusion 

zones in the 2,173.5-2,190.5 kHz band within 1 km of coast station facilities, whose 

coordinates are listed in Tables D-2 and D-3. This amounts to 0.022 percent of the 
D-2 

bandwidth between 1.7 MHz and 80 MHz and less than 0.004 percent of U.S. territorial 

area, or less than 0.0000008 percent of national spectrum resource between 1.7 MHz and 

80 MHz. This special protection requirement will prevent substantial endangerment of 

distress alerting by ships and aircraft in oceanic areas. In the event that an Access BPL 

operator plans to deploy numerous Access BPL devices at these frequencies in areas near 

these exclusion zones, consult with the following point of contact may best ensure that 

harmful interference is prevented at these facilities: 

Commandant (CG 622) 

U.S. Coast Guard 

2100 2nd Street, S.W. 

Washington, DC 20593 – 0001 

Telephone: (202) 267 – 2860 

E-Mail: cgcomms@comdt.uscg.mil

Table D-2: Exclusion zones for U.S. Coast Guard Coast Stations 

Locale Latitude Longitude 

Group Guam 13o 35' 23" N 144o 50' 24" E 

GANTSEC 18o 18' 00" N 65o 46' 59" W 

Puerto Rico 18o 28' 11" N 66o 07' 47" W 

Honolulu 21o 18' 21" N 157o 53' 23" W 

Group Key West 24o 33' 35" N 81o 47' 59" W 

Trumbo Point CG Base 24o 33' 58" N 81o 47' 57" W 

Miami 25o 37' 28" N 80o 23' 07" W 

Everglades Park 25o 50' 10" N 81o 23' 13" W 

Group Saint Petersburg (Everglades) 25o 51' 00" N 81o 23' 24" W 

Station Ft. Lauderdale 26o 05' 21" N 80o 06' 40" W 

Station Ft. Myers Beach 26o 27' 34" N 81o 57' 15" W 

Group Miami (Ft. Pierce) 27o 27' 36" N 80o 18' 36" W 

Station Ft. Pierce 27o 27' 50" N 80o 18' 27" W 

Group Corpus Christi 27o 42' 01" N 97o 16' 11" W 

Group Corpus Christi 27o 42' 06" N 97o 16' 45" W 

ESD Saint Petersburg 27o 45' 21" N 82o 37' 32" W 

Group Saint Petersburg 27o 46' 11" N 82o 37' 47" W 

Station Port O'Connor 28o 26' 03" N 96o 25' 39" W 

S. Padre Island 28o 26' 22" N 97o 09' 56" W 

Freeport 28o 55' 59" N 95o 16' 59" W 

Group Galveston (Freeport) 28o 56' 24" N 95o 17' 59" W 

Station YANKEETOWN 29o 01' 51" N 82o 43' 39" W 

Station Ponce De Leon Inlet 29o 03' 50" N 81o 55' 01" W 

Group New Orleans (Grand Isle) 29o 15' 53" N 89o 57' 26" W 

Galveston 29o 19' 59" N 94o 46' 18" W 

Kapalan 29o 20' 04" N 94o 47' 17" W 

Sabine 29o 43' 42" N 93o 52' 14" W 

New Orleans 30o 01' 17" N 90o 07' 24" W 

Panama City 30o 10' 01" N 85o 45' 04" W 

Group Mobile (Panama City) 30o 10' 12" N 85o 45' 36" W 
D-3 

Locale Latitude Longitude 

ANT Jacksonville Beach 30o 17' 16" N 81o 24' 10" W 

Pensacola 30o 20' 24" N 87o 18' 17" W 

Group Mayport 30o 23' 10" N 81o 26' 01" W 

Group Mayport 30o 23' 24" N 81o 25' 48" W 

Ft. Morgan 30o 39' 07" N 88o 03' 12" W 

Tybee Lighthouse 32o 01' 15" N 80o 50' 39" W 

Point Loma Lighthouse 32o 39' 56" N 117o 14' 34" W 

Point Loma 32o 40' 07" N 117o 14' 14" W 

Activities San Diego 32o 43' 59" N 117o 11' 13" W 

Group Charleston (Sullivan's Island) 32o 45' 00" N 79o 49' 47" W 

Sullivan's Island Lights 32o 45' 02" N 79o 50' 03" W 

Group Charleston 32o 46' 25" N 79o 56' 37" W 

Group San Diego 32o 52' 48" N 118o 26' 23" W 

San Pedro 33o 45' 00" N 118o 15' 58" W 

Group Fort Macon 33o 53' 24" N 78o 01' 48" W 

Point Mugu 33o 59' 32" N 119o 07' 18" W 

Group LA / Long Beach 34o 07' 11" N 119o 06' 35" W 

Channel Island 34o 09' 17" N 119o 13' 11" W 

Station Oxnard Channel Island 34o 09' 43" N 119o 13' 19" W 

Group Ft. Macon 34o 41' 48" N 76o 40' 59" W 

Group Cape Hatteras 35o 13' 59" N 75o 31' 59" W 

Group Cape Hatteras 35o 15' 35" N 75o 31' 48" W 

Morro Bay (Cambria) 35o 31' 21" N 121o 03' 21" W 

San Clemente Island 32o 50' 24" N 118o 23' 15" W 

Point Pinos 36o 38' 12" N 121o 56' 06" W 

CAMSLANT 36o 43' 47" N 76o 01' 11" W 

Group Hampton Roads 36o 53' 01" N 76o 21' 10" W 

Point Montara 37o 31' 23" N 122o 30' 47" W 

Point Montara Lighthouse 37o 32' 09" N 122o 31' 08" W 

Group San Francisco 37o 32' 23" N 122o 31' 11" W 

Group San Francisco 37o 48' 34" N 122o 21' 55" W 

Point Bonita 37o 49' 00" N 122o 31' 41" W 

Group Eastern Shores 37o 55' 47" N 75o 22' 47" W 

Group Eastern Shore 37o 55' 50" N 75o 22' 58" W 

CAMSPAC 38o 06' 00" N 122o 55' 48" W 

Point Arena Lighthouse 38o 57' 18" N 124o 44' 28" W 

Point Arena 38o 57' 36" N 123o 44' 23" W 

Group Atlantic City 39o 20' 59" N 74o 27' 42" W 

Activities New York 40o 36' 06" N 74o 03' 36" W 

Activities New York 40o 37' 11" N 74o 04' 11" W 

ESD Moriches Hut 40o 47' 19" N 72o 44' 53" W 

Group Moriches 40o 47' 23" N 72o 45' 00" W 

Group Humboldt Bay 40o 58' 41" N 124o 06' 31" W 

Group Humboldt Bay 40o 58' 47" N 124o 06' 35" W 

Trinidad Head 41o 03' 15" N 124o 09' 02" W 

Group Long Island Sound 41o 16' 12" N 72o 54' 00" W 

Station New Haven 41o 16' 12" N 72o 54' 06" W 
D-4 

Locale Latitude Longitude 

Station Brant Point 41o 17' 21" N 70o 05' 31" W 

Group Woods Hole 41o 17' 23" N 70o 04' 47" W 

Station Castle Hill 41o 27' 46" N 71o 21' 42" W 

Group Woods Hole 41o 30' 30" N 70o 41' 42" W 

Boston Area 41o 40' 12" N 70o 31' 48" W 

Station Provincetown 42o 01' 48" N 70o 12' 42" W 

Eastern Point 42o 36' 24" N 70o 39' 26" W 

Cape Blanco 42o 50' 16" N 124o 33' 52" W 

Group North Bend 43o 24' 16" N 124o 13' 22" W 

Group North Bend 43o 24' 35" N 124o 14' 23" W 

Cape Elizabeth 43o 33' 28" N 70o 12' 00" W 

Group South Portland 43o 38' 24" N 70o 15' 00" W 

Group South Portland 43o 38' 45" N 70o 14' 51" W 

Group SW Harbor 44o 16' 19" N 68o 18' 27" W 

Group Southwest Harbor 44o 16' 48" N 68o 18' 36" W 

Fort Stevens, Oregon 46o 09' 14" N 123o 53' 07" W 

Group Astoria 46o 09' 29" N 123o 31' 48" W 

Group Astoria 46o 09' 35" N 123o 53' 24" W 

La Push 47o 49' 00" N 124o 37' 59" W 

Station Quillayute River 47o 54' 49" N 124o 38' 01" W 

Port Angeles 48o 07' 59" N 123o 25' 59" W 

Group Port Angeles 48o 08' 24" N 123o 24' 35" W 

Juneau (Sitka) 57o 05' 24" N 135o 15' 35" W 

Kodiak 57o 40' 47" N 152o 28' 47" W 

Valdez (Cape Hinchinbrook) 60o 26' 23" N 146o 25' 48" W 

Table D-3: Exclusion zones for Maritime Public Coast Stations 

Licensee Name Location Latitude Longitude 

Shipcom LLC Marina Del Ray, CA 33o 56' 21" N 118o 27' 14" W

Globe Wireless Rio Vista, CA 38o 11' 55" N 121o 48' 34" W

Avalon Communications 

Corp 

St. Thomas, VI 18o 21' 19" N 64o 56' 48" W

Globe Wireless Bishopville, MD 38o 24' 10" N 75o 12' 59" W

Shipcom LLC Mobile, AL 30o 40' 07" N 88o 10' 23" W

Shipcom, LLC Coden, AL 30o 22' 35" N 88o 12' 20" W

Globe Wireless Pearl River, LA 30o 22' 13" N 89o 47' 26" W

Globe Wireless Kahalelani, HI 21o 10' 33" N 157o 10' 39" W

Globe Wireless Palo Alto, CA 37o 26' 44" N 122o 06' 48" W

Globe Wireless Agana, GU 13o 29' 22" N 144o 49' 39" E

D.2.2 Radioastronomy Observatories 

Using correlation techniques, the Very Large Array (VLA) receivers operate with 

desired signal levels that are well below ambient noise levels and rely on the protection 
D-5 

criteria specified by the International Telecommunication Union Radiocommunication 

Sector (ITU-R) for radioastronomy observatories. Figure D-1 illustrates the antenna 

array at this facility near Socorro, New Mexico. The BPL Memorandum Opinion and 

Order defined an exclusion zone where Access BPL systems operating on overhead MV 

power lines in the 73.0 – 74.6 MHz band should be no closer than 65 km from the 

coordinates of the VLA facility.5 The coordinate at the center of the VLA is 34° 04’ 

43.50”N, 107° 37’ 03.82”W. Figure D-2 shows the specified protection radii within the 

National Radio Astronomy Observatory. The BPL rules also state that Access BPL using 

LV power lines or underground power lines using the 73.0 – 74.6 MHz band should be 

excluded within 47 km from the coordinates of the VLA facility. The analyses in Section 

3.3.3 confirmed that these exclusion zone radii are reasonable to limit the power flux 

density (PFD) to levels defined for this frequency band by the ITU-R. This amounts to 

2.04 percent of the bandwidth between 1.7 MHz and 80 MHz and less than 0.028 percent 

of U.S. territorial area, or less than 0.0006 percent of national spectrum resource between 

1.7 MHz and 80 MHz. 

Figure D-1: Very Large Array (VLA) radioastronomy observatory 

 

5 See Amendment of Part 15 regarding new requirements and measurement guidelines for Access 

Broadband over Power Line Systems, ET Docket No. 04-37, Memorandum Opinion and Order, released 

August 7, 2006, (“BPL Memorandum Opinion and Order”), at ¶¶ 57 - 59. 
D-6 

Figure D-2: VLA protection radii for overhead Access BPL shown within the National Radio 

Astronomy Observatory near Socorro, New Mexico. 

D.3 CONSULTATION AREAS 

Part 15 of the Commission’s rules for carrier current systems apply the same field 

strength limits for wanted and unwanted emissions, and so, consultation between BPL 

service providers and radio operators should not be limited to the fundamental 

frequencies intentionally used in Access BPL systems. Moreover, frequencies used by 

many communications receivers in the 1.7 – 30 MHz frequency range are subject to 

change in the long-term and over hourly or shorter time frames. In light of these factors 

and given that the consultation areas needed for BPL systems are small, consultation 

should be required for all planned Access BPL operations at all frequencies of potential 

concern in these consultation areas. These consultation areas are: 

• For frequencies in the 1.7 – 30 MHz frequency range, the areas within 4 km of 

facilities located at the following coordinates: 

- the Commission’s protected field offices listed in 47 C.F.R. § 0.121, the 

point-of-contact for which is specified in that section; 

- the aeronautical stations listed in Tables D-4 and D-5; 

- the land stations listed in Tables D-6 and D-7; 
D-7 

• For frequencies in the 1.7 – 80 MHz frequency range, the areas within 4 km of 

facilities located at the coordinates specified for radio astronomy facilities in US 

311. 

• For frequencies in the 1.7 – 80 MHz frequency range, the area within 1 km of the 

Table Mountain Radio Receiving Zone, the coordinates and point of contact for 

which are specified in 47 C.F.R. § 21.113(b). 

• For frequencies in the 1.7 – 30 MHz frequency range, the areas within 37 km of 

radar receiver facilities located at the coordinates specified in Table D-8. 

Point of contact

U.S. Coast Guard HQ 

Division of Spectrum Management CG-622 

2100 Second St., SW. Rm. 6611 

Washington, DC 20593 

Tel: 202-267-6036 

Fax: 202-267-4106 

Email: jtaboada@comdt.uscg.mil

Table D-4: Consultation Area Coordinates for Aeronautical (OR) Stations (1.7 – 30 MHz) 

Command Name Location Latitude Longitude 

Washington Arlington, VA 38o 51' 07" N 77o 02' 15" W 

Cape Cod Cape Cod, MA 41o 42' 00" N 70o 30' 00" W 

Atlantic City Atlantic City, NJ 39o 20' 59" N 74o 27' 42" W 

Elizabeth City Elizabeth City. NC 36o 15' 53" N 76o 10' 32" W 

Savannah Savannah, GA 32o 01' 30" N 81o 08' 30" W 

Miami Opa Locka, FL 25o 54' 22" N 80o 16' 01" W 

Clearwater Clearwater, FL 27o 54' 27" N 82o 41' 29" W 

Borinquen Aguadilla, PR 18o 18' 36" N 67o 04' 48" W 

New Orleans New Orleans, LA 29o 49' 31" N 90o 02' 06" W 

Traverse City Traverse City, MI 44o 44' 24" N 85o 34' 54" W 

San Diego San Diego, CA 32o 43' 33" N 117o 10' 15" W 

Sacramento McClellan AFB, CA 38o 40' 06" N 121o 24' 04" W 

Astoria Warrenton, OR 46o 25' 18" N 123o 47' 46" W 

North Bend North Bend, OR 43o 24' 39" N 124o 14' 35" W 

Barbers Point Kapolei, HI 21o 18' 01" N 158o 04' 15" W 

Kodiak Kodiak, AK 57o 44' 19" N 152o 30' 18" W 

Houston Houston, TX 29o 45' 00" N 95o 22' 00" W 

Detroit Mt. Clemens, MI 42o 36' 05" N 82o 50' 12" W 

San Francisco San Francisco, CA 37o 37' 58" N 122o 23' 20" W 

Los Angeles Los Angeles, CA 33o 56' 36" N 118o 23' 48" W 
D-8 

Command Name Location Latitude Longitude 

Humboldt Bay McKinleyville, CA 40o 58' 39" N 124o 06' 45" W 

Port Angeles Port Angeles, WA 48o 08' 25" N 123o 24' 48" W 

Sitka Sitka, AK 57o 05' 50" N 135o 21' 58" W 

Point of contact

ARINC 

2551 Riva Road 

Annapolis, MD 21401 

Tel: 1-800-633-6882 

Fax: 410-266-2329 

Email: bplnotifications@arinc.com 

www.arinc.com

Table D-5: Consultation Area Coordinates for Aeronautical Receive Stations (1.7 – 30 MHz) 

Locale Latitude Longitude 

Southampton, NY 40o 55’ 15”N 72o 23’ 41” W 

Molokai, HI 21o 12’ 23” N 157o 12’ 30” W 

Oahu, HI 21o 22’ 27” N 158o 05’ 56” W 

Half Moon Bay, CA 37o 39’ 64” N 122o 24’ 44” W 

Pt. Reyes, CA 38o 06’ 00” N 122o 56’ 00” W 

Barrow, AK 71o 17’ 24” N 156o 40’ 12” W 

Guam 13o 25’ 12” N 144o 48’ 00” E (note: 

Eastern Hemisphere) 

NY Comm Center, NY 40o 46’ 48” N 73o 05’ 46” W 

Cedar Rapids, IA 42o 02’ 05.0” N 91o 38’ 37.6” W 

Beaumont, CA 33o 54’ 27.1” N 116o 59’ 49.1” W 

Fairfield, TX 31o 47’ 02.6” N 96o 47’ 03.0” W 

Houston, TX 29o 36’ 35.8” N 95o 16’ 54.8” W 

Miami, FL 25o 49’ 05” N 80o 18’ 28” W 

Point Of Contact

U.S. Coast Guard HQ 

Division of Spectrum Management CG-622 

2100 Second St., SW. Rm. 6611 

Washington, DC 20593 

Tel: 202-267-6036 

Fax: 202-267-4106 

Email: jtaboada@comdt.uscg.mil

Table D-6: Consultation Area Coordinates for Land Stations, Set 1 (1.7–30 MHz) 

Command Name Location Latitude Longitude 

COMMSTA Boston Maspee, MA 41o 24' 00" N 70o 18' 57" W

Camslant Chesapeake, VA 36o 33' 59" N 76o 15' 23" W

COMMSTA Miami Miami, FL 25o 36' 58" N 80o 23' 04" W
D-9 

Command Name Location Latitude Longitude 

COMMSTA New Orleans Belle Chasse, IA 29o 52' 40" N 89o 54' 46" W

Camspac Pt. Reyes Sta, CA 38o 06' 00" N 122o 55' 48" W

COMMSTA Honolulu Wahiawa, HI 21o 31' 08" N 157o 59' 28" W

COMMSTA Kodiak Kodiak, AK 57o 04' 26" N 152o 28' 20" W

Guam Finegayan, GU 13o 53' 08" N 144o 50' 20" E

Point of contact

COTHEN Technical Support Center 

COTHEN Program Manager 

Tel: (800) 829-6336 

Table D-7: Consultation Area Coordinates for Land Stations, Set 2 (1.7 – 30 MHz) 

Site Name Latitude Longitude 

Albuquerque, NM 35o 05' 02" N 105o 34' 23" W 

Arecibo, PR 18o 17' 26" N 66o 22' 33" W 

Atlanta, GA 32o 33' 06" N 84o 23' 35" W 

Beaufort, SC 34o 34' 22" N 76o 09' 48" W 

Cape Charles, VA 37o 05' 37" N 75o 58' 06" W 

Cedar Rapids, IA 42o 00' 09" N 91o 17' 39" W 

Denver, CO 39o 15' 45" N 103o 34' 23" W 

Fort Myers, FL 81o 31' 20" N 26o 20' 01" W 

Kansas City, MO 38o 22' 10" N 93o 21' 48" W 

Las Vegas, NV 36o 21' 15" N 114o 17' 33" W 

Lovelock, NV 40o 03' 07" N 118o 18' 56" W 

Memphis, TN 34o 21' 57" N 90o 02' 43" W 

Miami, FL 25o 46' 20" N 80o 28' 48" W 

Morehead City, NC 34o 34' 50" N 78o 13' 59" W 

Oklahoma City, OK 34o 30' 52" N 97o 30' 52" W 

Orlando, FL 28o 31' 30" N 80o 48' 58" W 

Reno, NV 38o 31' 12" N 119o 14' 37" W 

Sarasota, FL 27o 12' 41" N 81o 31' 20" W 

Wilmington, NC 34o 29' 24" N 78o 04' 31" W 

Point Of Contact

ROTHR Deputy Program Manager 

(540) 653-3624 

Table D-8: Consultation Area Coordinates for Radar Receiver Stations (1.7 – 30 MHz) 

Latitude/Longitude 

18° 01' N / 66o 30' W 

28° 05' N / 98° 43' W 

36° 34' N / 76° 18' W