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National Institute of

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U.S. Department of Commerce

NIST Technical Note 1549

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NIST Technical Note 1549

Electromagnetic Airframe Penetration

Measurements of the FAA's 737-200

Chriss Grosvenor, David Novotny, Dennis Camel!, Galen Koepke

Electromagnetics Division

Electromagnetics and Electrical Engineering Laboratory

National Institute of Standards and Technology

Boulder, CO 80305-3328

Robert!. Johnk

National Telecommunication and Information Agency

Institute for Telecommunications Sciences

Boulder, CO 80305-3328

Seturnino Canales

Formerly with the National Institute of Standards and Technology

5857 Scenic Ave.

Firestone, CO 80504-5652

March 2010

U.S. Department of Commerce

Gary Locke, Secretary

National Institute of Standards and Technology

Patrick Gallagher, Director
National Institute of Standards U.S. Government Printing Office For Sale by the

and Technology Washington: 2010 Superintendent of Documents

Technical Note 1 549 U.S. Government Printing Office

Natl. Inst. Stand. Technol. Stop SSOP, Washington, DC 20402-0001

Tech. Note 1 549 Phone: (202) 51 2-1800

237 pages (March 2010) Fax: (202) 512-2250

CODEN: NTNOEF Internet: bookstore.gpo.gov
Contents

1

.

History and Background 2

2. Overview 4

3. Initial Simulations, Theoretical Analysis and Measurements 5

3.1 Frequency Averaging 5

3.2 Ground Bounce and other Effects 10

3.2.1 Ground Bounce in a Laboratory Environment 10

3.2.1 .1 Time-of-flight for Direct Antenna Response and

Ground Bounce Response Effects 10

3.2.1.2 Simulating Ground Bounce into a Shielded Enclosure 11

3.2.2 Ground Bounce in an Aircraft Testing Environment 19

3.2.3 Effects of Varying Ground Conditions on Antenna Measurements. ... 21

3.2.4 Effects of Ground Bounce for Aircraft Measurements 23

3.3 Antenna Gain 26

4. Measurement System 28

5. Measurement of Electromagnetic Airframe Penetration 30

5.1 Reference Measurements 33

6. Aircraft Penetration Measurements — Overview 38

6.

1

Extrapolation Results 39

6.2 Penetration into aircraft from 45° Extrapolation Line 41

6.2.1 Measurements in Flight Deck 41

6.2.2 Measurements in Front Galley 44

6.2.3 Measurements in Rear Galley 46

6.2.4 Measurements in Mid-Passenger Cabin 50

6.3 Mid-Passenger Cabin Penetration Results 53

6.3.1 Single-Position Quadrant Measurements 53

6.3.2 Rear Quadrant Sector Measurements 56

6.4 Intercompartmental Insertion Loss Measurements 63

6.4. 1 Main Cabin to Main Cabin 63

6.4.1.1 Combined TEM horn antenna positions 63

6.4. 1 .2 Individual TEM horn antenna positions 66

ni
6.4.1.3 Combined DRG horn antenna positions 79

6.4.1.4 Individual DRG horn antenna positions 82

6.4.2 Main Cabin to Flight Deck 94

6.4.2.1 Combined DRG horn antenna positions 94

6.4.2.2 Individual DRG horn antenna positions 97

6.4.2.3 Combined TEM horn antenna positions 106

6.4.2.4 Individual TEM horn antenna positions 109

6.4.3 Main Cabin to Cargo Bay 120

6.4.3.1 Combined DRG horn antenna positions 120

6.4.3.2 Individual DRG horn antenna positions 123

6.4.3.3 Combined TEM horn antenna positions 132

6.4.3.4 Individual TEM horn antenna positions 135

6.4.4 Main Cabin to Avionics Bay 147

6.4.4.1 Combined DRG horn antenna positions 147

6.4.4.2 Individual DRG horn antenna positions 150

6.4.4.3 Combined TEM horn antenna positions 158

6.4.4.4 Individual TEM horn antenna positions 161

6.4.5 Cargo Bay to Avionics Bay 169

6.4.5.1 Combined TEM horn antenna positions 169

6.4.5.2 Individual TEM horn antenna positions 173

6.4.5.3 Combined DRG horn antenna positions 181

6.4.5.4 Individual DRG horn antenna positions 184

7. Uncertainty Analysis 192

8. Summary and Conclusions 194

9. References 195

IV
Appendix A. TEM and DRG Horn Boresight Gain Characteristics 198

Appendix B. Number of Positions versus Average Power 200

Appendix C. Whisker-Box Plots for the Bombardier Global

5000 and the Beechcraft Premier lA 203

Appendix D. Numerical Modeling of the FAA's 737-200 212

Appendix Dl. The Reference Box Artifact 213

Appendix D2. Simulation of the FAA's 737-200 218

Appendix E. 737-200 Measurement Equipment List 233

Electromagnetic Airframe Penetration

Measurements for the FAA

Passenger Jet 737-200

Chriss Grosvenor, David Novotny, Dennis Camell, and Galen Koepke

Electromagnetics Division

National Institute of Standards and Technology

325 Broadway

Boulder, CO 80305

and

Robert T. Johnk

National Telecommunication and Information Agency

Institute for Telecommunication Sciences

325 Broadway

Boulder, CO 80305

and

Setumino Canales

Formerly with NIST

5857 Scenic Ave.

Firestone, CO 80504-5652

The National Institute ofStandards and Technology has completed shielding

effectiveness/penetration studies on three different aircraft types for the Federal Aviation

Administration. The studies are used to understand the cavity coupling characteristics between

antennas placed in various compartments inside the aircraft and antennas placed at various

angular positions around an aircraft. This document shows how penetration varies as afunction

offrequency, antenna type, antenna polarization, and cavity susceptibilityfor a 737-200

passengerJet. The document discusses initial numerical analysis, antenna gain dependence, and

ground bounce effects and how they impact the data. Internal coupling between two antennas

placed in the aircraft at different locations was studied and a statistical analysis ofthe insertion

loss between various compartments is also presented.

Key words: aircraft; cavity coupling; digital signal processing; HIRF; numerical modeling;

penetration; shielding effectiveness; synthetic time-domain measurements.
1. History and Background

The Federal Aviation Administration (FAA) is responsible for the safety of civilian aviation [1].

Included in this function is the responsibility to ensure that the flight hardware is safe from an

electromagnetic interference (EMI) event that could jam navigational equipment and render

flight hardware inoperable. The avionics systems are flight critical, and uninterrupted operation

is required in order to fly the aircraft safely. There is a history of EMI-induced system failures in

both military and commercial electronic systems [2-5]. This is one of the reasons why

manufacturers of aircraft are required to submit test data showing that their aircraft can provide

enough protection or shielding of interior flight systems from outside electromagnetic sources. These tests are called high intensity radiated field (HIRE) measurements and are used to determine the shielding effectiveness of the aircraft from radiating sources [6-13]. HIRE sources

are only those emitters that intentionally generate emissions. HIRE sources include radio and

TV transmitters, airport and weather radar, and various military systems, both ground-based and

airborne, such as surveillance radar, electronic warfare (EW) systems, and electromagnetic

weapons. These radiating sources can also include ground tracking radars, electromagnetic pulse

(EMP) events, both natural and man-made, such as lightning or EMP ordnance, cell phones,

electrostatic discharge (ESD), and other events. The hazard levels for these interferers have been

studied [14] and are incorporated into HIRE test methodologies [15].

Manufacturer's HIRE data are given to the EAA for inspection but are often not accompanied by

a detailed test report as to how the tests were performed. Often the data have very noise-like

characteristics and are difficult to interpret. The National Institute of Standards and Technology

(NIST) has had previous experience with measuring the shielding effectiveness of aircraft [16 -

19]. Eor this reason, the EAA approached NIST to provide guidance on the interpretation of the

HIRE measurement results. The project was three-fold: (1) analyze canonical structures by use of numerical methods, (2) develop efficient measurement and data-processing methods based on

the numerically modeled results, and (3) perform an extensive set of measurements on an actual

aircraft. Once these tasks were completed, the EAA would have a more complete understanding

of common measurement methods supported by detailed numerical analyses.

The Field Parameters and EMC Applications Project of the National Institute of Standards and

Technology (NIST) has now completed shielding effectiveness/penetration studies of three

representative aircraft for the Federal Aviation Administration (EAA). These studies will

provide the EAA with the procedures and data-reduction techniques for typical low-signal-level

airframe penetration for high-intensity radiated field (HIRE) attenuation/shielding tests. This

technical note addresses aircraft shielding tests conducted on a 737-200 passenger jet owned and

operated by the FAA. Two additional reports have been completed involving studies of (1) a Bombardier Global 5000 business jet owned and operated by the EAA [18] and (2) a Beechcraft

Premier lA ovmed by the Hawker-Beechcraft Corporation [19]. The Bombardier Global 5000

represents a commercial business jet, and the Premier lA represents a typical carbon-composite

aircraft. By measuring all three aircraft and comparing them, we have the potential to provide a "design roadmap" for the optimization of HIRE testing standards for the electromagnetic

compatibility (EMC) aircraft manufacturing community.
The FAA currently has specific certification poHcies addressing the effects of HIRF on an

aircraft's electrical and electronic systems that have been applied since around 1990 [15]. This

document is presently being rewritten, and a new draft is expected to be completed in 2010. In the current FAA document, the regulatory authorities and industry have defined HIRF

environments, requirements for aircraft HIRF" protection, and methods for testing and verifying

the level of HIRF protection. Most of reference [15] discusses HIRF testing for electronic and

electrical subsystems, which this technical note does not address. In this technical note, we

specifically address both high- and low-level airframe shielding compliance testing. The HIRF

procedures are found in Section 6.6.2.6 and Section 6.6.4 of Reference [15].

The basic problem is to evaluate the coupling of an external source into a large,

electromagnetically leaky cavity [20 - 27]. The cavity could represent the whole aircraft or part

of it (cargo bay, flight deck, etc.), depending on the expected vulnerability. In a typical HIRF

measurement, the measurement system is calibrated, and a reference measurement is taken

without the aircraft embedded in the test setup. The aircraft is then placed into the test setup and

various measurements are taken in susceptible cavities. These attenuation tests are typically

conducted by use of either mechanical stirring or frequency-stirring methods [13-15]. The

airframe attenuation is calculated by use of the following equation:

. _ e r _ reference measurement ^1>. atten •

• cavity measurement

where Aamn is the airframe attenuation and S.E. is defined as the shielding effectiveness. These

numbers, expressed in decibels, are typically positive, so that the more positive the number, the

greater the protection the aircraft provides to electromagnetic fields, and as the number

approaches zero we expect almost no shielding protection. The aircraft HIRF attenuation data

vary as a function of frequency, physical position of the measurement antenna, angle of

incidence, polarization, characteristics of the aircraft, and configuration of the test site. After a company tests and processes the data, the information is given to the FAA, which uses it in

conjunction with the subsystem susceptibility tests to determine an aircraft's HIRF vulnerability.

The detailed method used to process aircraft HIRF attenuation data is not well documented and

is closely held by the handful of test service providers. Therefore, the interpretation of the data

is not immediately obvious to the certification engineer. This technical note and the previous

two technical notes consider attenuation measurements as a function of frequency, antenna

position, antenna type, and cavity selection. Our data-processing methodology will be shown in

detail. Using this information, we hope to provide guidelines for both the FAA and test engineers to develop a uniform and transparent test method for data processing and

documentation. We know that the confidence levels are expected to depend on the number of

sample points (measurement geometries), but we should be able to assess the trade-offs between

measurement effort (sample number) and risk (confidence level).
2. Overview

This report summarizes results of two measurement efforts conducted by the Field Parameters

and EMC Applications Project team of NIST. This effort consisted of an extensive series of

penetration, internal, and ground-condition measurements performed on a 737-200 passenger jet

owned and operated by the FAA. The aircraft was tested at the FAA site in Atlantic City, New

Jersey during two periods from October 2004 to October 2005. The purpose of these efforts is to provide the FAA with a database of penetration and insertion loss data on the 737-200 passenger

jet.

Both efforts utilized NIST-developed measurement systems consisting of ultra-wideband

transverse electromagnetic (TEM) horn antennas, 3115 dual-ridged guided (DRG) horn antennas,

commercially available vector network analyzers (VNAs), interconnecting transmission media,

and an amplifier for the second effort. The first effort measured penetration from approximately

100 MHz to 2.5 GHz. Interconnections between transmitting and receiving antennas were made

using an 1 1 GHz precision, analog electro-optic link. The second effort combined both the

1 1 GHz and the 1 8GHz precision, analog electro-optic links. These efforts were the first time

NIST researchers used a broadband, analog, electro-optic link with a COTS (commercially

available off-the-shelf) VNA for airframe shielding studies up to 18 GHz. Shielding data were

obtained from a direct comparison of two measurements: (1) a transmission measurement

between boresighted antennas located outside the aircraft to obtain a reference, and (2)

transmission measurements with one antenna located inside a selected compartment of the

aircraft and a pair of horizontally and vertically polarized antennas for both low-frequency-band

and high-frequency-band antennas located outside the aircraft at specified locations. Shielding

data were obtained by comparing processed reference and aircraft transmission data. This was

achieved by use of an efficient sequence of Fourier and inverse Fourier transformations,

frequency domain convolutions, and filtering combined with time gating and frequency

averaging. Shielding values were obtained by taking the ratio of the gated amplitude spectra of

the aircraft measurement and the gated amplitude spectra of the references. Data smoothing was

performed by use of the frequency-averaging of signal power over a specified bandwidth as described in [16]:

K»^)=^"^"M^) 2N+\ . „

(1)

Shielding data were obtained with a receiving antenna located in one of four internal

compartments: (1) the main passenger cabin, (2) the flight deck, (3) the cargo bay, and (4) the

avionics bay. A pair of transmitting antennas was positioned outside the aircraft at a fixed height

of approximately 5 m, which is the approximate height of the windows, at a fixed distance of

23 m from the center of the aircraft. The transmitting antennas were boresighted at the center of

the aircraft, and data were obtained for both the horizontal and vertical polarizations. We based

our tests on HIRE standard test procedures and other questions we felt were important to ask.

These standards are concerned with detecting possible leakage into the aircraft. Key areas include the flight deck, the avionics bay, any windows/doors/joints, and the wing/tail section of

the fuselage. During our first effort, we developed a test plan designed to understand the effect of
varying ground conditions on the data [28], and how many positions are necessary to fully

characterize an electrically large object and to fully characterize the fields penetrating into the

aircraft for a particular high-frequency limit [29-32]. For this reason, we included a number of

angular positions to study penetration apertures around the aircraft and at six positions around

the rear one-fourth sector of the aircraft at a constant distance from the center of the aircraft.

Finally, we concluded with an extensive set of internal coupling measurements designed to understand the interaction between compartments and the reverberation characteristics of the

aircraft. This first effort consisted of the following measurements: (1) Extrapolation

measurements at 6.1 m (20 ft.), 9.1 m (30 ft.), 12.1 m (40 ft.), 15.2 m (50 ft.), 23.5 m (75 ft.), and

30.1 m (100 ft.); (2) Extrapolation measurements at 15.2 m, 23.5 m, and 30.5 m for ground

conditions including the tarmac and a sheet of rFoil (radiant barrier foil), which consists of a

layer of polyethylene bubbles bonded to and sandwiched between two highly reflective surfaces

[33], for both vertical and horizontal polarization; (3) sector measurements at 90°, 100°, 1 10°,

120°, 125°, 130°, 135°, 140°, 145°, 150°, 160°, 170° and 180° to look at the angular dependence

of radiating apertures. Finally, in the first effort, we concluded with a set of internal coupling

measurements to understand the reverberant environment internal to the aircraft. An aircraft's

level of electromagnetic field protection, referred to as shielding, depends on the level of

treatment, the compartment, the frequency, the transmitting antenna polarization, and the angle

of illumination. In this document, we will display penetration values, which are the reciprocal of

shielding values. In the graphs that follow, a penetration near dB means electromagnetic fields can easily penetrate into that part of the aircraft. Penetration levels for the FAA's Boeing 737-

200 commercial aircraft range from approximately -10 dB to -40 dB. The dynamic range of

this system is a function of the compartment in which it is located. For the system in the main

cabin, the estimated dynamic range is -70 dB at 1000 MHz and -50 dB at 3000 MHz. For the

system in the cargo bay, the estimated dynamic range is -60 dB at 1 000 MHz and ^0 dB at 3000 MHz.

This report is divided into five main sections: (1) Initial theoretical and simulation analysis, (2) a description of the measurement system, (3) an overview of the measurement technique, (4) an overview of the signal processing, (5) a summary of results for the four different aircraft

compartments and various internal measurements, and (6) an uncertainty analysis. Appendices

A through E discuss the number of positions versus the average power, whisker-box plots

showing how frequency bandwidths affect the statistics of the Bombardier Global 5000 and

Beechcraft Premier lA results, simple numerical modeling results, an equipment list, and the gain

characteristics of the ultra-wideband antennas that were used.

3. Initial Simulations, Theoretical Analysis, and Measurements

3.1 Frequency averaging

We began these efforts by doing some theoretical analysis to understand the importance of

certain parameters and their impact on aircraft measurements. An initial finite-difference, timedomain (FDTD) model was developed for a pulsed source in free-space. Other models have

been developed for HIRE radiation levels [20-21]. Figure 1 shows the time-domain waveform

that results from the model. The electromagnetic fields can be seen emanating from the pulsed

source on the left to a monitor point on the right. A plot showing the initial time-domain pulse is
shown on the right. The onset of the impulse occurs at around 20 ns and the impulse response is around 2 ns. We then modeled a slot in an infinite ground plane as shown in Figure 2. The

pulsed source was on one side of the infinite ground plane, and the monitor point was on the

other. The frequency-domain waveform corresponding to Figure 2 is shown in Figure 3. The

plot shows the resonances that result from the electromagnetic waves penetrating through the slot and being received at the monitor point.

The next model took a portion of the infinite ground plane with the slot and backed it with a box

based on the dimensions of a reverberant box designed by NIST and the Naval Surface Warfare

Center. The dimensions were selected to permit sufficient modal density above 1 GHz, to achieve reverberant behavior inside the box, and to exhibit characteristics of an electrically large

cavity (see Figure 4). Aluminum was chosen for fabrication ease and its high electrical

conductivity. A rotatable aluminum paddle, powered by an external d.c. motor, was installed

within the box to provide mode-stirring. Five holes 1 .6 cm in diameter were randomly punched

on each side of the box. We chose this diameter so that all apertures were electrically small from

2 GHz to 4 GHz and to achieve a shielding effectiveness in the range of 20 dB to 30 dB. This

range of shielding values is based on theoretical guidelines and was verified by use of

measurements performed in the reverberation chamber [25]. The FDTD box model is shown in

Figure 5. The time-domain and frequency-domain signatures of the slotted box problem are shown in Figures 6 and 7. The time-domain figures show that the signal reaches the monitor

point starting at around 25 ns. From this time forward we obtain a slowly decaying electric field

amplitude. When an Fast-Fourier Transform (FFT) is applied to the time-domain waveform we

obtain the frequency-domain plot, also shown in Figure 6. The result shows a noisy looking

waveform where not much important information is available. To bring out important details

and minimize the noise, we averaged the frequency-domain data over a small bandwidth of

frequencies [16]. Figure 7 shows the result of frequency averaging for bandwidths of 50 MHz

and 100 MHz, respectively. The wider the bandwidth the greater the effect of smoothing the

data; however, we do see that the original resonances that occurred for the slit in the infinite

round plane are now revealed.

2000-J

-2000 -^

-4000-

20 30 40 Time (ns)

50 60

Figure 1 . FDTD Modeling and result for pulsed source in free space.
Pulsed

Source

Monitor

Point

Figure 2. Resonant slot in an infinite ground plane.

Slot Resonances

-10

oa -20

-a

^*-^ co

-^^ -30 «

u-<_i <us

0) -40

-50

-60

1000 2000

Frequency (MHz)

3000

Figure 3. Slot resonances from a slit in an infinite

ground plane.
Figure 4. Aluminum reverberant box designed to simulate 20 to 30 dB of shielding.

Pulsed

Source

Monitor

Point

Figure 5. FDTD Model of the NIST/Naval Surface Warfare Center

Shielded Enclosure.
150

-100

150

100 200 300 400

Time (ns)

500

Figure 6. Time-domain and frequency-domain waveforms for a pulsed source in a slotted box.

^ -30

-50

50 MHz

1000 2000 Frequency (MHz)

3000

1000 2000 Frequency (MHz)

Figure 7. A 50 MHz and 100 MHz frequency averaging bandwidth applied to the waveform in Figure 6.
3.2 Ground Bounce and other Effects

3.2.1 Ground Bounce in a Laboratory Environment

3.2.1.1 Time-of-flight for direct antenna response and ground bounce response

The effect of ground bounce and ground conditions are important when one measures

penetration into an aircraft either sitting on a hangar floor or on the tarmac [28]. This is because

ground bounce is not an effect seen when an aircraft is in flight as the electromagnetic radiating

field impinges on the aircraft. Ideally, the aircraft should be measured in flight to avoid these

types of effects; however costs and ease of measurements are impractical. To understand the

effect of ground bounce on our measurements, we began with the following analysis. We

measure the transmission in our laboratory for two 1 .2 m TEM horn antennas. These antennas

have a short impulse response [34], so the initial direct antenna-to-antenna response can be

isolated from the response due to the interaction with the ground, also known as ground bounce.

A diagram showing the measurement setup is shown in Figure 8. From the geometry, we can

determine the signal delay from one antenna to another for both the direct component and the

ground-bounce component. If the antenna apertures are separated by 1.9 m and the additional

delay due to 15 cm of cable and the antenna transition from the end of one calibration reference

plane to another is taken into account, then the time of flight for the direct signal response will be

approximately 23 ns. We can compute the time of flight for the ground-bounce component by

knowing that the aperture center of the antenna was 1 .7 m above the ground plane. The

geometrical calculations tell us that the signal due to ground bounce should arrive at approximately 27 ns. Figure 9 shows two time-domain responses for the direct transmission

component and the ground-bounce component. The black trace shows an initial direct

1.2 m TEM

horn antennas

1.9m

Styrofoam

supports

Ground plane

3

Figure 8. Laboratory setup for transmission measurement between 1.2 m TEM horn antennas.

10
0.015 ^

0.01

0.005 -

U

-a3

Q. <

-0.005

-0.01

-0.015

n

1.2 m TEM Horns

(Vpol - Horn 1 to Horn 2)

with absorber no absorber

20 40

Time (ns)

Figure 9. Typical reference measurement setup for 1 .2 m TEM horn

antennas on a laboratory ground plane. Distances are shown for the

direct path and the secondary ground-bounce path.

component for signal transmission between the antennas and a second component due to the

ground bounce. If absorber is placed on the ground plane between the antennas, then the red

trace shows that the ground bounce has been minimized due to the presence of the absorber. By

looking at the initial time for both responses, we see that the direct antenna-to-antenna impulse

response begins at around 23 ns and the response due to the ground plane reflection occurs at around 27 ns, just as our geometrical ray -tracing model predicted.

3.2.1.2 Simulating ground bounce into a shielded enclosure

To look at ground-bounce effects and how they impact measurements into a shielded cavity, we

set up a shielded cavity in our laboratory at NIST. The measurement setup is shown in Figure

10. A reference measurement was taken with the antennas at a height of 1 .50 m and separated by

a distance of 2 m. The antenna was placed inside the box (aperture facing the door), and another

measurement with the door of the box fully open was taken. The door of the box was closed

until a 15.24 cm (6 in.) gap existed at the top, and a measurement was taken. More

measurements were taken with a 7.62 cm (3 in.) and a 2.54 cm (1 in.) gap. One measurement

was taken with the antenna facing toward the back of the shielded box. The antenna was

lowered on the tripod to a height of 1.35 m and measured with the 15.24 cm, 7.62 cm, and

2.54 cm gaps. Again the antenna was lowered to a height of 1.21 m and measurements of the

same door gaps were taken. A time-domain reference waveform is shown in Figure 1 1 for two

DRG horn antennas mounted on tripods and separated by a distance of 2 m at a height of 1.5 m.

11
2 m

A

Q

A

Shielded Box

Id

Ground Plane

1.50 m T

1.3 A y \^m T

1.2.1 m

Figure 10. Measurement setup for ground-bounce experiment.

The red box shows the direct antenna-to-antenna response and the blue box shows the groundbounce response. The antennas were placed into the shielded enclosure with the front door to the

box fully open, and the time-domain waveform, shown in Figure 12. was acquired. Differences

between the two waveforms can be seen due to the presence of the box, but the ground-bounce

0.02 Direct Antenna to Antenna Response

0.01

u

3

q.E<

-0.01

-0.02

20 Time (ns)

Figure 1 1 . Time-domain reference waveform for two

DRG antennas separated by 2 m.

12
response is still visible. The frequency spectrum for the two DRG antennas on tripods is shown

in Figure 13. The black trace shows the frequency spectrum for the entire captured waveform

including the direct antenna-to-anterma response and ground-bounce response. The red trace shows the frequency spectrum of the direct response only (the ground bounce has been timegated out). The blue trace shows the frequency spectrum of the ground bounce with the direct

response gated out. The separate, gated components (the direct anterma-to-antenna response and

the ground bounce component) were then added together to see whether we obtained the original

frequency spectrum. This is shown in Figure 14. The full spectrum is shown by the black trace,

which includes all frequency responses including the laboratory environment. The separated,

gated, ground-bounce component added to the gated, direct component is shown by the red trace. The extra noise-like behavior on the black trace is due to the laboratory's response.

Then we wanted to investigate the waveforms as the door to the shielded enclosure was shut

incrementally. The ground bounce will begin to be unseparable from the initial impulse response

of the antenna. However, if we assume that the ground bounce response occurs at the same time

and we gate this part of the waveform from the total response, what happens to the frequency

spectrum? Figure 1 5 shows the time-domain responses for a DRG antenna in the shielded box

with the door open 1 5.24 cm and the transmitting antenna at a height of 1 .5 m and 1 .21 m,

respectively. Figure 16 shows the time-domain responses for a DRG antenna in the shielded box

with the door open 2.54 cm and the transmitting antenna at a height of 1 .5 m and 1 .21 m,

respectively. The location where the ground bounce is expected is shown by the blue box as in

Figures 1 1 and 12. The frequency spectra for the reference measurement (black trace) and the

respective shielded box waveforms (blue trace) were plotted and are shown in Figure 1 7 for the

shielded box door open 1 5.24 cm and the transmitting antenna at a height of 1 .5 m and 1.21 m,

respectively. Figure 18 shows the frequency spectra for the shielded box door open 1 inch and

the transmitting antenna at a height of 1.5 m and 1.21 m, respectively. The direct spectrum of

the reference and the shielded box was overlaid with the ground bounce gated out for both

measurements. The direct antenna-to-antenna reference is shown by the red trace, and the direct

antenna-to-antenna response for the shielded box is shown by the green trace. The conclusion

for these measurements is that the ground bounce affects only the frequency content of the

waveform and not the amplitude. Figure 19 shows data from the reference measurement and

Figure 20 shows the results from the shielded cavity measurements. These graphs show the

relationship between the direct component, the ground bounce component, and the laboratory or

cavity response. Figure 19 shows the entire waveform (black trace), including the ground

bounce, laboratory and direct antenna-to-antenna responses, a waveform (red trace) with the

ground bounce and laboratory responses gated out, leaving just the direct antenna-to-antenna

response, the laboratory response (blue trace) with the direct and ground bounce gated out, and a corresponding system noise floor. Figure 19 shows the same information but with the shielded

cavity. The additional traces show the shielded cavity direct antenna-to-antenna component plus

ground bounce and cavity response (light blue trace), and direct-to-direct antenna response with

shielded cavity (green trace). The purple trace, in this case, is the shielded cavity response with

the direct anterma-to-antenna response and ground bounce both gated out.

13
T3

aj -a3

03

•T3 3

u.uz

r Direct Antenna to Antenna Response

/

0.01 -

-

»

Oround Bounce

1/

11

IMm |\ /\/v^nA^\'>^^^——-^^N^vv-\^^—^

—

u

-0.01 —

-0.02 1

'

1

'

1 10 20 Time (ns) 30 40

Figure 12. Time-domain reference waveform for one DRG antenna on a tripod and the other in the shielded

box, separated by 2 m.

-20

-40 -

-60

-80 -

100

-120

2 m Reference

Direct Antenna-to-Antenna Response

Ground Bounce Response Only

2000 4000

Frequency (MHz)

6000

Figure 13. Frequency-domain reference waveform for two DRG antennas

separated by 2 m. The black trace is the spectrum that includes the direct

response and ground bounce; the red line is the spectrum of the direct

response only; the blue line shows the spectrum of the ground bounce.

14
03-o

T33

00

-20

-24

-28 -

-32 -

-36 -

-40

Direct Antenna Component and Ground Bounce

Gated Direct Component added

to the Gated Ground Bounce Component

2000 4000

Frequency (MHz)

6000

Figure 14. Frequency-domain waveforms for the full spectrum (red trace)

compared to the gated, ground-bounce component added to the gated, direct

component.

15
0.005 —

0.004 -

0.003

0,002

-aJ 0,001

CLE<

«

n

00

c^ -0,001

-0,002

-0,003

-0,004

-0.005

Ground Bounce

^ location from initial file

/WyiAr-'^AA'^'^'^/^-^^AA'^AAAA- <

0.005

0.004 —I

0003

0.002

T31 0.001

CLE

1.50 m height

10

-0.001

-0.002

-0.003

-0.004

-0.005

Ground Bounce

location from initial file

1.21 m height

20 Time (ns) 30 40 10 20 Time (ns) 30

Figure 15. Time-domain waveforms for a DRG antenna in shielded box with transmit antennas

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 15.24 cm.

0.005

0.004 H

0.003

0.002

= 0.001

a.p<

•a

c^ -0.001 -

-0.002

-0.003

-0.004

-0.005

Ground Bounce

, location from mitial file

1.50 m height

0.005

0.004

0.003 —

0.002 —

-a^ 0.001

D-E5

a

c

00 Ji -0.001

-0.002

-0.003

-0.004

-0.005

Ground Bounce V location from mitial file

1.21 m height

20 Time (ns) 30 40 10

\ 20 Time (ns) 30 40

Figure 1 6. Time-domain waveforms for a DRG antenna in shielded box with transmit antennas

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 2.54 cm.

16
-10

-20

-30

-40

-50

-60

-70

-80

-90

-100

1.50 m height

-10

-20

1.21 m height

Reference at 2 m

Antenna in Box - Door Open 1 5.24 cm

150 cm Xmit Height Reference - Direct Only

Antenna in Box

Ground Bounce Removed

-40

T3

-g -50 c

00 I

-60-

'^ -70

-80-

-90

-100

Ay^

^i^^fW

Reference at 2 m

Antenna in Box - Door Open 1 5 24 cm

121 cmXmit Height Reference - Direct Only Antenna in Box

Ground Bounce Removed

2000 4000

Frequency (MHz)

6000 2000 4000

Frequency (MFlz) 6000

Figure 17. Frequency domain waveforms for a DRG antenna in shielded box with transmit

antennas heights of 1 .5 m and 1 .21 m, respectively, with the door of the box open 1 5.24 cm (6

in.).

-10 -I

-20

-30

-40

-50

-60

-70

-80

-90

-100

-20

-30

cr -40

-50

-60

-70

f'"^^-'"~''VM.v----_^

Reference at 2 Antenna in Box - Door

1 50 cm Xmit Heit Reference - Direct Only

Antenna in Box

_, Oroiind Bounce Rernnved

-90 -

enjiQ -100

Reference at 2 m

Antenna in Box - Dj) 121 cm Xmil

Reference - Direct ( Antenna in Box

Ground Bounce Removed

2000 4000

Frequency (MFlz) 6000 2000 4000

Frequency (MHz)

6000

Figure 1 8. Frequency domain waveforms for a DRG antenna in shielded box with transmit antennas

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 2.54 cm (1 in.).

17
0^

Direct Antenna Component and Ground Bounce

Gated Direct Component added

to the Gated Ground Bounce Component

Laboratory Response

System Noise Floor

1 P r 2000 4000

Frequency (MHz)

6000

Figure 1 9. Frequency spectrum showing the 2 m reference

measurement showing how the various components of the signal

add and subtract.

Reference at 2 m

Antenna in Box - Door Open

- 150 cm Xmit Height

Reference - Direct Only Antenna in Box

Ground Bounce Removed

Cavity Response

System Noise Floor

-100 2000 4000

Frequency (MHz)

6000

Figure 20. Frequency spectrum showing results of shielded box

experiment at 150 cm height - door open. Cavity response is found

by subtracting the gated ground bounce from the full spectrum.

18
3.2.2 Ground Bounce in an Aircraft Testing Environment

To take the understanding we gained from the laboratory, we can apply a similar analysis for an

aircraft as was done in Section 3.2.1.1. A schematic is shown in Figure 21 of a measurement

where the antennas are located at approximately 4 m above the tarmac at the FAA's Atlantic City

location. In a typical reference measurement, the antennas are located on a tower 4 m above the

tarmac and separated by 23.0 m (75 ft.). Performing the same geometrical analysis as above, we

determine that the time of flight should be around 76 ns for the direct antenna-to-antenna

response, and the ground reflection should appear around 81 ns. Figure 22 is a time-domain plot

of an actual reference measurement taken at the FAA Atlantic City facility showing a direct

antenna-to-antenna component around 74 ns and a ground-bounce component around 76.5 ns. Typically in this type of reference measurement we time-gate out the reflection due to the ground

bounce, which transforms this measurement into a free-space reference. This free-space

reference is then used to deconvolve antenna effects from the measurement to get aircraft

penetration values. If we try to time-gate out the ground bounce from our aircraft measurement

(prior to deconvolution) we run into problems. Since we try to maintain the same antenna

separations for an antenna inside the aircraft, we can assume that the ground bounce will again

appear at around 77 ns, and the initial antenna-to-antenna response should be seen at around

74 ns. A time-domain plot of a measurement at the 70 degree position for the receive DRG horn

antenna located in the main passenger cabin is shown in Figure 23. In this figure, we see that the

initial response occurs at approximately 73 ns, and what appears to be a secondary response

occurs at around 90 ns, which is a delay of 1 3 ns from where we would expect the ground

bounce to show up in our measurement. This would result in a geometrical difference of

approximately 4 m or 12 ft. This analysis suggests that the secondary response is due not to ground bounce but to some other interaction of the electromagnetic waves with either the aircraft or something internal to the aircraft, and therefore the ground bounce is contained within the first initial decay response and cannot be gated out of the measurement.

Transmitting antennas ,

Direct antenna-to-antenna coupling path (d, = 22.86 m)

Receiving

'•antennas

Optical Fiber

22.86 m

Reference Measurement

Figure 2 1 . Schematic showing typical measurement setup

for a reference measurement between antenna towers.

19
Time Graph

10.528m

Figure 22. Time-domain graphs for DRG Hpol antennas showing the direct antenna-to- antenna response and the secondary reflection due to the ground for an antenna separation of

approximately 23 m and an antenna height of 4 m.

Time Graph

Figure 23. A time-domain plot showing a 23 m measurement for a transmitting DRG Hpol

antenna at the 70 degree position and a DRG receiving antenna in the main passenger cabin.

20
3.2.3 Effects of varying ground conditions on antenna measurements

What happens when measurements are performed over the earth when the surface changes from

earth or pavement to metal? This question was answered on a previous measurement effort at the GM Proving Grounds in March 2004.

We went to understand the problems they were experiencing with field uniformity on their large,

outdoor automotive test antenna range [35-37] due to varying ground conditions along the

measurement path. The antenna range is shown in Figure 24. To study this problem, a numerical simulation was developed for the FM (frequency modulation) band from 88 MHz to 108 MHz. Two different ground conditions were modeled. The first was "earth", consisting of a

semi-infinite asphalt medium, having a relative permittivity e' = 5, relative permeability ]i' = 1.0,

and a conductivity of a = 0.01 Siemens/m. A 5 m by 5 m perfectly conducting ground plane was

then placed over the ground to simulate the turntable found inside the measurement radome at the GM facility. The simulated environment is depicted in Figure 25. A 1.5 m long transmitting

dipole was positioned above the "earth" interface or ground plane at a height of 2 m. The results

of the simulation are shown in Figure 26 with the dipole in the horizontal polarization. Figure

26a shows the "earth" ground and that interactions with the "earth" ground are minimal. When a ground plane is added over the earth, the field uniformity is minimally disrupted as shown in

Figure 26b. The fields looking down from the dipole over the ground plane are shown in Figure

26c. The results for the dipole in the vertical polarization of this simulation are shown in Figure

27. For the "earth". Figure 27a shows uniform fields tilting slightly upwards. When the ground

plane is installed, the field uniformity is greatly disturbed, as shown in Figure 27b. The fields

looking down from the dipole over the ground plane are shown in Figure 27c. These simulations

show that dissimilar ground interfaces along the measurement path disrupt the fields more than

just having a single continuous ground interface.

''SiiiifllHilll'

' '^MJfePifeteii''!9

#i= '^"^-Dome/Turntable

TransrS!t AnT(gnha

I^^^^I^^^H^I^H^^H^H^^^ "^^"^^""^S^^WPHHii^^^%^m

i- ""

Figure 24. Outdoor Automotive Antenna Test Range.

21
' Viewer (F9) I gm_ground_plQne.nec ] ;,.^

1.5m Long Transmitting Dipole

Located 2m high &

X=214m down range

Real GroundX^

Epsr = 5.0 ^ i Sigma = 10mS/m

Perfectly Conducting

Ground Plane

sAwsl 20 "iti

TlKila Ph Pn' IzfT

Idaill R(b|

Rolci Col I

I P Truerad

r A»t P Ground

jStiucfaje »!

QuaStv —

-U. Jj.

FPS Trr»_ Its ns

Figure 25. Simulation of GM Turntable over an asphalt dielectric medium.

j^^^^M^MMMHM ^^^^^^^Baa

So» itt« t«M ^^^TM ^^^E

H,i»>\Mtm] V.OObIi

2

fc3

•*' i.

110

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647 ________

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as ' so

«0 ^' "^ -.? X2 =' »2 -K

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- «»^-

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,3)7

C3.

'^^ -17 76; l« -50 -*0 30 20 to 00 10 20 30 JO 50 X 1

V-OQrt. 0*.WOM<)_M*M_h<»j out H>cX^0:Z.2S

«0 .40 OO .20 -10 06 10 20 30 40 iO X

(a) (b) (c)

Figure 26. Simulation of GM turntable over an asphalt dielectric medium. The dipole is in the horizontal

polarization. The results in (a) show the field uniformity above "earth". The results in (b) show the field uniformity above a 5 m by 5 m "turntable". The results in (c) are the fields looking down from the dipole over the ground plane.

22
9m NwfMU 1^^Ei^

ciri«l>///»l l97 3W/a(•.x-as.v^o.z-iw

z

157 , J m

'« „

!iO jj

1J1 Jl

in _^__

no ^^HBj

t«i wo "

m. "

«< so io 30 ; 10 CO 10 : )0 *0 !0 X

«•.-«-««

t

Ground

Plane

30 10 1 00 10 :o JO *o so

E

» K uV/b l«r X- 3 7. V-J t& Z1

90 4(1 JO 20 U 00 10 20 JO *0 ?C X

(a) (b) (c)

Figure 27. Simulation of GM turntable over an asphalt dielectric medium. The dipole is in the vertical polarization. The results in (a) show the field uniformity above "earth". The results in (b) show the field uniformity above a 5 m by 5 m "turntable". The results in (c) are the fields looking down from the dipole over the ground plane.

3.2.4 Effects of ground bounce for aircraft measurements

To understand how ground conditions affect the measurements, we decided to investigate the

difference between reflections from the tarmac and reflections from a sheet of rFoil. The

measurement setup is shown in Figure 28. These measurements were taken along the 45°

extrapolation line (Figure 44) at distances of 15.2 m (50 ft.), 23.5 m (75 ft.), and 30.5 m (100 ft.). These results are shown in Figure 29. The green traces are results for tarmac ground conditions,

and the orange traces are for the rFoil ground conditions. Vertical polarization results are shown

by the solid traces, and the horizontal polarization results are shown by the dotted traces. It is interesting to note that the results for vertical polarization show a slight polarization inversion for

the rFoil which is what we would expect from theory [38]. However, for the horizontal

polarization there is no polarization inversion. The differences in magnitude are anywhere from

dB to 10 dB depending on the frequency.

23
||p'^^ilM»-i»*

Figure 28. Photographs showing Rfoii laid out beneath aircraft for the various

ground condition experiments.

24
(ap) uouEiiausj (gp)UOI113Ja3U3d

(OP) uoijBjjausd (9P) U0UBJJ3U3d

FF

—— ^ )^ L-.' h- H ce: oi n n

OLQ- LiJ OJ LU LU

1-; o o o o n n fV LU > X > X o i/l ,^ ^^ ^^ .^^ Di <r: n-; ^ •r: n J?l o o o o

en (U

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r^ i/-^ OJ o 3 <\> h OlJ sz o

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(aP)U0UEJl3U3d {aP)U0UEiJ3U3d

25
3.3 Antenna Gain

A simulation was performed to understand how antenna gain impacts the field penetration into an aircraft. Using two antenna types we evaluated the shielding effectiveness. The first was a

short dipole and the second an aperture antenna to represent a DRG horn anterma. These models

are shown in Figure 30. Simulated reference measurements were taken for both antennas at the same distances, and then the receiving antennas were placed at the same position inside a shielded structure. The shielding effectiveness of the structure was obtained and a 200 MHz

frequency averaging was applied to obtain an average shielding value per unit frequency. The

theoretical gains were then computed for each antenna and the gain difference was computed.

This was then plotted against the shielding difference of the two antenna types for the two

shielding simulations and is shown in Figure 31. The result of the simulation shows that with

higher antenna gains, higher shielding values can be obtained. For a reference measurement, the

gains of both antennas are taken into account by the measurement. When the receiving anterma is placed inside a cavity, the gain of the cavity plus antenna changes and the gain of the receiving

anterma must be corrected. Thus we correct for this gain in the processing of the data. This is considered in our uncertainty analysis. Figure 32 shows an actual set of measurements and the

difference in penetration that can occur between applying a gain correction (black trace) and not

applying gain correction (red trace) for a measurement on a Bombardier Global 5000 [18] with

the receiving antenna in the main passenger cabin and the transmitting tower at the 0° position.

Short

Dipole

Aperture Antenna

Similar to Dual-Ridged

Horn

Figure 30. Two antenna types used for antenna gain simulation.

26
16^

»

"aa

12

9S o

R^4^ 0) Q

«a 8

ens

"O

0) JSO) 4

0) Q

Computed Shielding Difference-200 MHz Average

Theoretical Gain Difference

500 1000 1500 2000

Frequency (MHz)

2500 3000

Figure 31. Shielding difference plotted against the

theoretical gain difference.

0-1

-20

-o

-40

-60

Bombardier

DRG - Hpol

angular scan 1 - 08 position Gain correction No Gain Correction

4000

\

'

\ 8000 12000

Frequency (MHz)

16000

I 20000

Figure 32. Difference between using a gain correction and no

gain correction for a DRG horn antenna.

27
4. Measurement System

The configuration of the NIST measurement systems for these aircraft measurements is shown in

Figures 33, 34, and 35. Figure 33 shows the equipment used on the receiving side of the system

inside the aircraft. The transmitting side of the aircraft measurement system is shown in Figures

34 and 35 for (a) the original system that made measurements to 3000 MHz, and (b) the

upgraded system that made measurements up to 18 GHz, respectively. The system consists of: (1) a VNA, (2) two transmitting TEM horn antennas, and two DRG horn antennas configured for

the horizontal and vertical polarizations, respectively, (3) a receiving TEM horn antenna and

DRG antenna, (4) two coaxial microwave switches to select the polarization of the transmit

antennas, and (5) two precision analog electro-optic links to cover both fi-equency bands (only

the 1 1 GHz optical link was used during the first effort) and to provide an interconnection

between the transmitting antennas outside the aircraft and the receiving antenna inside. Both

links provide a significant improvement in performance over that of conventional microwave

cables. The optical links exhibit low transmission losses and low noise, and do not pick up

common-mode noise from environmental ambient signals. The optical links also improve

dynamic range and have better immunity from electromagnetic interference. The heart of this

system is a commercially available VNA that has been configured to acquire complex

transmission data (S21, in-phase and quadrature signals). During the first effort, the VNA was

limited to a maximum of 1601 points due to internal hardware limitations. During the second

effort, the VNA was limited to a maximum of 16001 frequencies; however for both efforts, we

developed software that extends the number of frequencies to any desired value. If we need

more than the maximum number of points per window, then the software will subdivide a given

frequency range into a user-selected number of either 1601 or 16001 point sub-bands. The DRG

horn antennas operate from 1 GHz to 18 GHz and were configured by use of two bands, resulting

in 32002 equally spaced measurement points from approximately 0.5 MHz to 18 GHz. The

TEM horn antennas operate from 0.1 GHz to 4 GHz and were configured by use of one band,

resulting in 6401 equally spaced measurement points from approximately 0.5 MHz to 4 GHz. A

reduced frequency spacing is necessary to avoid problems due to aliasing. Prior to connecting

the cables to the antennas, all channels were calibrated to remove systematic transmission effects

due to cabling, switches, and the frequency and phase variations of the optical transmission link.

This procedure calibrates the system with respect to the input of the transmitting and the output

of the receiving antennas. Three NIST-developed ultra-wideband TEM horn antennas were used:

two 1 .2 m antennas on a tower located outside of the aircraft, either to transmit horizontally and

vertically polarized fields, and a more compact 36 cm TEM horn located in a pre-selected

aircraft compartment to detect energy coupled into the airframe. For the higher-frequency bands,

three commercially available DRG antennas were used: two on the same transmitting tower

located outside of the aircraft to transmit horizontally and vertically polarized fields, and a DRG

antenna located in the same preselected aircraft compartment to detect energy coupled into the

airframe. The frequency data were digitized and transferred to a laptop computer for subsequent

data analysis and signal processing.

28
Optical Link to Optical Receiver

Figure 33. Airframe shielding measurement system (receiving side). The reverberant nature of the airframe permits the reception of both horizontally and vertically polarized signals.

Transmitting TEM

horn antennas

\

Channel 1. 2 H-pol Channel 3,4 V-pol

\

Transmitting

DRG

horn antennas

(Side view)

Tower

Transmitting TEM

horn antennas

Channel

Channel 3. H

V-pol

(Top View)

Transmitting DRG

horn antennas

Laptop 2-way

microwave

switch

1 1 GHz Optical ®<l II -link receiver iX^ Optical fiber

from aircraft

Figure 34. Transmitting side of the airframe shielding measurement system for

measurements to 3000 MHz.

29
Transmitting TEM

horn antermas

Transmitting TEM

horn_antenn_as_ _^^

Channel j i^ /T^

Channel 1 >~

H-pol

Channel 2 V-pol

Precision microwave

cables

2-way

microwave

switch

Transmitting

DRG

horn antennas

(Side view)

Tower

(Top View)

Transmitting DRG

horn antennas

Laptop

1 1 GHz Optical " MffOTpffcal

- link receiver

ir--

Optical fiber

from aircraft

Figure 35. Transmitting side of the airframe shielding measurement system for

measurements to 1 8000 MHz.

5. Measurement of Electromagnetic Airframe Penetration

The extraction of airframe penetration characteristics requires a reference measurement without

the shield or cavity and then a measurement with the shield or cavity placed between the two

antennas. This two-step measurement process for an aircraft is shown in Figure 36. In the first step, a reference transmission measurement is performed by boresighting the transmitting and

receiving antennas at a fixed distance. The reference measurements were performed at a location

away from the aircraft in order to minimize reflections from the aircraft. This measurement

quantifies the energy incident on the aircraft, and enables us to calibrate and remove the

frequency-dependent effects of the antennas and interconnecting hardware. In the second step,

the receiving antenna was placed in a selected aircraft compartment; the transmitting antennas were placed at fixed locations, external to the aircraft, and stepped-frequency transmission data were acquired.

The reference and airframe data were processed by use of a sequence of filtering, Fourier

transforms, and time gating to obtain the penetration values. The basic signal-processing

sequence through which the data were obtained is shown in Figure 37. The raw frequency data were first filtered to maximize the signal-to-noise ratio and to minimize effects from the lowfrequency cut-off of our electro-optic link. Next, a tapered frequency-domain window was

30
applied to both sets of data to reduce Gibbs ringing in subsequent processing. An inverse Fourier

transform (IFT) was then applied to the processed data to obtain time-domain waveforms. Time

gates were then applied to isolate the desired portions of waveforms and remove undesired

portions. In the case of the reference, the time gate was applied to isolate the direct antenna-toantenna coupling and remove the effects of ground bounce and late-time reflections. We use this to reference every measurement to the attenuation seen in free space. Time gating was applied to the airframe data to isolate either the direct illumination, the direct propagation path between the

two antennas, or the reverberant fields that are the reflected waves in the aircraft. Reflections

due to ground bounce are embedded in the waveforms at this distance and therefore cannot be

removed by time-gating. The time-gated data sets were then transformed back into the

frequency domain, and the penetration (PE), was computed from the deconvolution:

2

"^42 iS^^^d airframe) PE^DC (2) S^2 {gated reference

)

where 5*42 {gated reference) is the antenna-to-antenna coupling with environmental effects gated

out. The signal propagates from port 4 and is transmitted to port 2. 542 {gated airframe) is the

airframe transmission with gating applied to minimize noise. Since the reference and airframe

measurements are typically carried out at different distances, a distance correction {DC) was

applied:

Transmitting antennas ,

5 m

Receiving

antennas

Reference Measurement

Optical Fiber

Transmitting

antennas/ O

Figure 36. Two-step airframe shielding measurement procedure

used in the FAA's Boeing 737-200 evaluation.

31
DC(^5) = 201og,o

D

D.ref (3)

where D is the distance from the aperture of the transmitting antenna to the geometric center of

the aircraft and Dre/is the distance between the reference antennas. A detailed description of this

procedure is given in [16]. Thus, our definition of penetration is based on a comparison of a

direct antenna-to-antenna coupling and signal transmission through the airframe. The

penetration, as we define it here, is the reciprocal of shielding (in decibels, penetration is the

negative of shielding). We prefer to display results in terms of penetration because of a better

graphical display and to normalize the results by our reference measurement.

Single-aspect penetration characteristics for aircraft exhibit rapid variations with frequency, due

to the large, complex cavity behavior of the aircraft. In order to obtain the volumetric-averaged

penetration for a compartment, the processed penetration data were frequency-averaged over a

specified bandwidth by use of the process shown in Figure 38. Averaging the penetration data

reduces the complex cavity variations, increases modal randomness, and highlights systematic

coupling effects, but may mask narrowband details, depending on the amount of averaging

applied. These effects are discussed in detail in references [16, 25, 26].

Transmission measurement through airframe

Stepped-frequency

aircraft data Background=0

1

Appropriate filter to emphasize signal

i Condition data for FT

and reduce Gibbs ringing

T

Apply time gate(s) to

isolate sample response

Remove conditioning For IFT

Stepped-frequency antenna reference Background=0

Appropriate filter to emphasize signal

i Condition data for FT

and reduce Gibbs ringing

J.

Apply time gate to isolate sample response I

Remove conditioning For IFT

Deconvolve airframe spectrum

with

reference spectrum

I

Frequency-domain

' Kaiser-Bessel window

<0 02 dB passband ripple >50 dB rejection

5 ns on/off transition Frequency-domain convolution

Apply distance correction

•* Frequency-domain

antenna correction

. Distance correction relative

to antenna-to-antenna reference

Appropriate filter to emphasize signal

Aircraft penetration

Figure 37. Signal-processing sequence to obtain airframe penetration.

32
Processed

penetration data

PEif)

Perform averaging over a selected

bandwidth (BW)

N

i=\

Frequency-averaged

penetration

Figure 38. The frequency-averaging definition.

5.1 Reference Measurements

The test setup for the reference measurements is shown in Figure 39. The transmitting antennas

are shown mounted on one tower with aperture centers located 4 m above the ground. The

receiving antennas were mounted on a second tower. The towers were constructed from PVC

pipes and plywood platforms to produce a low-density support structure with minimal scattering.

The antermas were then boresighted and a distance extrapolation was performed to determine an

optimal reference distance to minimize near-field effects and maximize the period between the

signal and ground bounce. We performed multiple reference measurements with antenna-toantenna separations ranging from 2 m to 35 m. We found that a separation of 6 m was optimal in

terms of accuracy and time separation. Two transmission measurements were performed namely, one each for the vertical and horizontal channels. This process required a manual reorientation

of the receiving antenna to be co-polarized with each of the transmitting antennas. Once the

reference data were taken, the receiving antenna was dismounted from the support tower and

placed at selected locations inside the aircraft. The external antenna tower and aircraft are shovm

in Figure 40. The reference waveforms for the DRG antenna are shown in Figures 41, 42, and

43. The reference waveforms for the TEM horn antenna are shown in Figures 42, 43, and 44.

The ungated time-domain reference waveforms are shown in Figures 41 and 44. The doublets

that occur at approximately 50 ns in Figure 41 and 60 ns in Figure 44 correspond to direct

antenna-to-anterma coupling. The subsequent waveform activity was due to a combination of

internal antenna reflections and environmental scattering due to ground bounce and reflections

from nearby objects. Figures 42 and 45 show the ungated frequency-domain responses for the

DRG and TEM horn references, respectively. The noise-like hash on the waveform is due to ground bounce and spurious reflections which were time-gated out of the reference

measurement. The frequency-domain transmission amplitude spectra of Figures 43 and 46 show

33
Figure 39. Reference measurement setup. The transmitting tower is configured for all measurements, and the receiving tower is configured for reference measurements only.

the impact of applying this time gate, thus isolating direct antenna-to-antenna coupling and

yielding the reference for penetration measurements.

Figure 40. The transmitting antennas placed on top of a support tower and

boresighted at the center of the aircraft.

34
0.15 Antenna-to-antenna response

n.E<

0.05 Ground bounce &

spurious reflections

o -0.05

-0.1

-0.15

60 Time (ns)

Figure 41 . Ungated time-domain transmission waveform for a DRG

antenna obtained at a separation of 6 m and horizontal polarization.

0-1

a

c

1000 2000

Frequency (MHz)

Figure 42. Ungated frequency-domain amplitude spectrum for a DRG horn

antenna obtained at a separation of 6 m and vertical polarization. Note the hashy

behavior due to the spurious reflections shown in Figure 41

.

35
T3

I

-100

1000 2000

Frequency (MHz)

Figure 43. Gated frequency-domain amplitude spectrum for the DRG

horn antenna corresponding to the waveform of Figure 41

.

0.08

0.04-

Antenna-to-antenna response

E<

op

oz

-0.04

-0.08

40 60 80 Time (ns)

100

Figure 44. Ungated time-domain transmission waveform for a TEM antenna obtained at a separation of 6.0 m and vertical

polarization.

36
T33

'E

-20

-40

-60

-80

-100

-120

1000 2000

Frequency (MHz)

3000

Figure 45. Ungated frequency-domain amplitude

spectrum for a TEM horn antenna obtained at a separation of 6.0 m and vertical polarization. Note the

scalloping due to the large ground-bounce reflection

shown in Figure 44.

-a

-20

-40

F -60

-80

100

-120

1000 2000

Frequency (MHz)

3000

Figure 46. Gated frequency-domain amplitude spectrum for the TEM

horn antenna corresponding to the waveform of Figure 44. 37
6. Airframe Penetration Measurements — Overview

We began by measuring the penetration at several extrapolation points on the 45° line, as shown

by the black X's in Figure 46. These measurements are completed for every effort to ensure the

system is performing correctly and to determine that the reference antenna separations are in the

far-field. The data for both measurement efforts will be presented in this section; therefore some

data will be shown for an upper frequency of 3 GHz, and other data are shown for an upper

frequency of 1 8 GHz. The following measurements were performed over the course of both

measurement efforts: (1) the transmitting antenna was placed along the 45° extrapolation line at the 23.5 m (75 ft.) distance, then the receiving antenna was placed in the front galley, the rear

galley, the flight deck, and the mid-passenger cabin; (2) the receiving anterma was placed in the

mid-passenger cabin, and the transmitting antenna was moved around the aircraft to the 0°, 90°,

135°, and 180° positions. At the 90° position the transmitting antenna was moved in a small

circle around this position to look at antenna pattern effects; (3) sector measurements were

performed with the receiving antenna in the mid-passenger cabin and the transmitting antenna

moved to the 90°, 100°, 110°, 120°, 125°, 130°, 135°, 140°, 145°, 150°, 160°, 170°, and 180°

positions; and (4) internal propagation between cavities were measured. The transmitting

antenna was placed in the mid-passenger cabin and the receiving antenna was placed in the flight

deck, the main cabin, the cargo bay, and the avionics bay. The transmitting antenna was then

moved to the cargo bay and the receiving antenna was located in the avionics bay. Each of these

positions is shown by the red X's in Figure 44. Where applicable, we applied antenna gain and

distance correction factors to maintain consistency in the results.

270

Figure 47. Test master graphic showing internal measurement positions (red X's),

Extrapolation distances (black X's), measurements around aircraft (blue, dashed

line) at a distance of 23 m (75 ft).

38
6.1 Extrapolation Results

We performed a set of extrapolation measurements from 6.1 m (20 ft) to 30.5 m (100 ft). The

transmitting antennas were moved along the 45° line and the receiving antennas were located in

the main cabin. These measurements were used to determine whether we were in the far-field

and to understand how penetration changes as a function of distance from the aircraft. Distance

correction was applied to the data by use of a reference distance of 6.1 m. These data are shown

in Figures 48 to 51 . These measurements show a spread in the data of about 7 dB to 10 dB

across the frequency spectrum for the DRG antennas and around 1 dB for the TEM horn

antennas. The large spread in the data is due mostly to the 6. 1 m distance for the DRG antennas

and the 6.1 m, 9.1 m and 30.5 m distances for the TEM horn antennas. If we remove these data

sets, we tighten up the spread to between 3 dB and 6 dB for both sets of antennas. We believe

this is because, at the closer distances, our antennas see only a spot size of the aircraft, but as we

move further from the aircraft the antennas see more of the aircraft and the surrounding

environment. The DRG antennas have higher directivity than the TEM horn antennas, which

corresponds to the greater spread in penetration data for the TEM horn antennas. These results

have been both corrected for distance and for antenna gain. A discussion of the gain for the

DRG horn antenna and TEM horn antenna is given in Appendix A.

-20

CQ-a

-40

-60

DRG - Hpol

6.1 m(20ft.)

9.1 ni(30ft.)

12.1 m(40ft.)

15.2 m (50 ft.) 23.5 m (75 ft.) 30.5 m (100 ft.)

500 1000 1500 2000 Frequency (MHz)

2500 3000

Figure 48. Extrapolation measurements for the DRG antenna,

horizontal polarization.

39
-n

-20

T3*^C

o

lUc

a. -40

-60

DRG - Vpol

6.1 ni(20ft.)

9.1 m(30ft.)

12.1 m(40ft.)

15.2 m (50 ft.) 23.5 m (75 ft.) 30.5 m (100 ft.)

I

'

I

'

500 1000 1500 2000 Frequency (MHz)

2500 3000

Figure 49. Extrapolation measurements for the DRG

antenna, vertical polarization.

CQT3

1000 Frequency (MHz)2000

Figure 50. Extrapolation measurements for the

TEM antenna, horizontal polarization.

40
c

1000 Frequency (MHz)

2000

Figure 5 1 . Extrapolation measurements for the

TEM antenna, vertical polarization.

6.2 Penetration into aircraft from 45° extrapolation line

These measurements were used to study penetration as a function of the receiving antenna's

internal position. To accomplish this, the receiving antenna was moved to several locations

within the aircraft. Internal receiving antennas were located in the flight deck, the front and rear

galleys, and the mid-passenger cabin. The transmitting antenna was located on the 45°

extrapolation line at 23.5 m (75 ft.). This location was chosen because we had performed more

than one measurement at this position. At some positions, more than one measurement was

taken.

6.2.1 Measurements in the Flight Deck

Figure 52 shows the placement of the receiving antennas for measurements taken at position 4 in

the flight deck (see Figure 53). The TEM horn antenna was placed on the pilot's seat facing the

outside of the aircraft. The DRG horn antenna was placed on the co-pilot's seat facing the

instrument panel. Results at this position are shown in Figure 53. The graph shows that

horizontally polarized fields allow greater penetration into the flight deck than vertically

polarized fields. The TEM results are shown at the lower frequencies (red and light blue traces)

and the DRG results are shown at the higher frequencies (orange and dark blue traces). The

horizontally polarized TEM horn antenna results show penetration values on the order of-15 dB

and the vertically polarized TEM horn antenna shows an average penetration around -22 dB.

The horizontally polarized DRG horn antenna results show penetration values of approximately

-15 dB, at around 4000 MHz with a constant decay up to 18,000 MHz, where values are approximately -30 dB. The vertically polarized DRG horn antenna starts with a penetration of

41
around -20 dB at 2000 MHz, has a sharp drop from 3000 MHz to 4000 MHz, and then has a

fairly constant value of -35 dB across the rest of the frequency band, with values ranging from

-30 dB to -40 dB, depending on the frequency.

The placement of the receiving antennas for measurements taken at position 5 (see Figure 55) in

the flight deck, is shown in Figure 54. The TEM horn antenna was in the pilot's seat pointing

upward toward the flight deck windows. The DRG horn antenna was in the co-pilot's seat pointing toward the ceiling of the flight deck. Results at this position are shown in Figure 55.

The graph shows that horizontally polarized fields allow greater penetration into the flight deck

than vertically polarized fields. The horizontally polarized TEM horn antenna results show

penetration values on the order of -10 dB at around 1000 MHz, and for the vertically polarized

TEM horn antenna penetration shows a peak value at around -12 dB at 1000 MHz. The

horizontally polarized DRG horn antenna penetration values rise from -20 dB to -15 dB from

1000 MHz to 2000 MHz and then have a constant decay up to 18,000 MHz, where we show

values around -30 dB. The vertically polarized DRG horn antenna values start with a

penetrafion of around -15 dB at 2000 MHz, drops from -15 dB to -35 dB from 2000 MHz to 6000 MHz and then has an average value around -30 dB across the rest of the frequency band,

with values ranging from -20 dB to -40 dB, depending on the frequency.

Figure 52. Placement of receiving DRG and TEM horn antennas in the flight deck for position 4.

42
Flight Deck - 45 degrees

position 4

^°° TEM - Hpol

DRG - Hpol

TEM - Vpol „„ DRG - Vpol

4000 8000 12000

Frequency (MHz)

16000 20000

Figure 53. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

the 45° extrapolation line and the receiving antennas placed in the flight deck.

/

k .Mk — ^^^

b2 i

s

^^^

s#

..i'''^ .j^KS

^«

.^v ^ V ^"^

Figure 54. Placement of receiving DRG and TEM horn antennas in the flight deck for position 5.

43
CQ

u

c

Cu

Flight Deck - 45 degrees

position 5 TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

4000 8000 12000 16000 20000

Frequency (MHz)

Figure 55. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

along the 45° extrapolation line and the receiving antennas placed in the flight deck.

6.2.2 Measurements in the Front Galley

The placement of the receiving antennas for measurements taken at position 3 (see Figure 57) in

the front galley is shown in Figure 56. The TEM horn antenna is shown pointing toward the

cabin door. The DRG horn antenna is shown pointing toward the galley closet on the opposite

side of the aisle. Results for this position are shown in Figure 57. The horizontally polarized

fields penetrate into the aircraft better than the vertically polarized fields. The horizontally

polarized TEM horn antenna peaks at a penetration value of - 1 5 dB between 1 000 MHz and

2000 MHz, and the vertically polarized TEM horn antennas peaks at a value of -1 8 dB between

1 000 MHz and 2000 MHz. The horizontally polarized DRG horn antenna penetration values

begin at -1 5 dB between 3000 MHz and 4000 MHz and drop to a value of approximately

-28 dB at 18,000 MHz. Penetration values for the vertically polarized DRG horn antenna begin

at a value of approximately -22 dB at 2000 MHz and drop to a value of -3 8 dB at 18,000 MHz.

These values are slightly higher than for the flight deck. This could be due to the contribution

from the windows in the mid-passenger cabin.

44
Figure 56. Placement of receiving DRG and TEM horn antennas in the front galley for position 3.

Front Galley - 45 degrees

position 3 TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

330 -^^ 30

300 / /

V

^75

\

\60

240\

1

\

\ /

^ /

/ /120

210 ^_ 150

4000 8000 12000 16000 20000

Frequency (MHz)

Figure 57. Penetration versus frequency for all antennas and polarizations for the transmitting tower placec

along the 45° extrapolation line and the receiving antennas placed in the front galley for position 3.

45
6.2.3 Measurements in the Rear Galley

The antennas were then moved to the rear galley and two sets of measurements were taken. The

placement of the receiving antennas, for measurements taken at position 6 (see Figure 59) in the

rear galley, is shown in Figure 58. The TEM horn antenna is shown pointing upward into the

comer between the ceiling and the rear cabin door. The DRG antenna is shown pointing toward

the corner between the bathroom area and the rear cabin door on the opposite side of the aisle. Results for this position are shown in Figure 59. The difference in penetration between the

horizontally polarized fields and the vertically polarized fields is not as pronounced as in the

previous measurements and are on the order of a few decibels at certain frequencies. The

horizontally polarized TEM horn antenna penetration values begin at a value around -30 dB at approximately 100 MHz and peak at a value of -20 dB at around 1000 MHz. The vertically

polarized TEM horn antenna penetration values begin at values around -35 dB at 100 MHz and

peak at a value of about -22 dB at 1000 MHz. The horizontally polarized DRG horn antenna

penetration values begin at a value of -23 dB at 1000 MHz, rise to a value of -20 dB at 4000 MHz, and then drop to a value of around -28 dB at 18,000 MHz. The vertically polarized

DRG horn antenna penetration values begin at a value of approximately -22 dB at 1000 MHz,

rise to a value of approximately -21 dB at 2000 MHz, and drop to a value of -30 dB at

1 8,000 MHz. The variation in penetration values is less dramatic than for the previous positions.

For measurements taken at position 7 (see Figure 61) in the rear galley, the receiving antennas were placed as shown in Figure 60. The TEM horn antenna is shown pointing upward toward

the ceiling and toward the front of the aircraft. The DRG antenna is shown pointing almost

directly toward the front of the aircraft in the horizontal polarization, but on the opposite side of

the aisle. Results for this position are shown in Figure 61 . The difference in penetration

between the horizontally polarized fields and the vertically polarized fields is now increased to around 5 dB to 10 dB as the frequency increases. The horizontally polarized fields have greater

penetration. The horizontally polarized TEM horn antenna penetration values begin at a value

around -30 dB at approximately 100 MHz and peak at a value of -20 dB at around 1500 MHz.

The vertically polarized TEM horn antenna penetration values begin at values around -35 dB at 100 MHz and peak at a value -25 dB at 1000 MHz. The horizontally polarized DRG horn

antenna penetration values begin at a value of -20 dB at 1 000 MHz, show values from -20 dB to -25 dB between 2000 MHz and 14000 MHz, and then vary from -20 dB to -25 dB from

1 5,000 MHz to 1 8,000 MHz. The vertically polarized DRG horn antenna peaks at a value of

approximately -20 dB at 2000 MHz, varies from -23 dB to -30 dB from 2000 MHz to 12,000 MHz and averages to a penetration value of -30 dB from 12,000 MHz to 18,000 MHz.

A distance correction is applied when the reference measurement distance and the shielding

measurement distance are different, as discussed at the beginning of Section 5. Common sense would lead us to process the data using the actual geometric distance between antermas;

however, in this type of an environment, this approach does not work because the actual flight

path is not known, due to multiple apertures. Typically, we use the geometric center of the

aircraft for distance corrections so that results can be compared. Another possibility is to observe the onset of the signal in the time-domain and use this value (converted to distance) to distance-correct the data. For this set of measurements in the rear galley, we applied a distance

correction of 29.3 m (96 ft.). Results for position 6 are shown in Figure 62, and results for

46
position 7 are shown in Figure 63. This experiment shows that penetration values can vary by

about 2 dB, depending on the distance correction that is used. The difference in distance

between the time-domain signal onset and the 23.5 m (75 ft.) is approximately 6 m. For

consistency between this technical note and previous technical notes, a 23.5 m (75 ft.) distance

correction has been used. The time-of-flight distance correction has not been used but could be a

topic of discussion for future measurements.

Figure 58. Placement of receiving DRG and TEM horn antennas in the rear galley for position 6.

47
-30 -

-40

Rear Galley - 45 degrees

position 6 TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

"^75 \ 60

/

/

/

\

k^^'

\

I

\ /

240\

//

\ /^ /120

210C_l^^^^^^^50

-50

4000 8000 12000 16000 20000

Frequency (MHz)

Figure 59. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

along the 45° extrapolation line and the receiving antennas placed in the rear galley at position 6.

Figure 60. Placement of receiving DRG and TEM horn antennas in the rear galley for position 7.

48
-o

c

u

a.

Rear Galley - 45 degrees

position 7 TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

/

330 ;^7^ 30 \

300/

/

/

/ 2fe

^75

\

\

\

\

\ 60

1 ^) '1'

240\

\

\

/X\^ /

/120 \ / " - -^X /

210 _^ 150

4000 8000 12000

Frequency (MHz)

16000 20000

Figure 61 . Penetration versus frequency for ail antennas and polarizations for the transmitting tower placed

along the 45° extrapolation line and the receiving antennas placed in the rear galley at position 7.

DRG-V

Rear Galley to 23.5 m(75ft.: 45 deg extrapjios 6 - Distance corrected to 23,5 m (75ft.) Distance corrected to 29 3 m (96 ft. (Time-domain distance)

8000 12000

Frequency (MHz)

16000 20000

Figure 62. Results showing penetration difference

due to distance correction factor for rear galley data.

49
DRG-V

Rear Galley to 23.5 m (75 ft.) 45 deg extrapjios 7 — Distance corrected to 23.5 m (75ft.) Distance corrected to 29.3 m (96 ft.) (Time domam distance)

8000 12000

Frequency (MHz)

16000 20000

Figure 63. Results showing penetration difference

due to distance correction factor for rear galley data.

6.2.4 Measurements in the Mid-Passenger Cabin

The final location for the extrapolation-line measurements was in the mid-passenger cabin. Two

sets of measurements were completed here. The placement of the receiving antennas, for

measurements taken at position 2 (see Figure 65) in the mid-passenger cabin, is shown in Figure

64. Both antennas were pointing toward the ceiling and were positioned at approximately the

same angles. Results for this position are shown in Figure 65. The horizontally polarized fields

have greater penetration than the vertically polarized fields. The horizontal polarized TEM horn

antenna penetration values begin at a value around -20 dB at approximately 100 MHz and peak

at a value of -10 dB at around 1000 MHz. The vertically polarized TEM horn antenna

penetration values begin at values around -25 dB at 100 MHz and peak at a value of -25 dB at 1000 MHz. The horizontally polarized DRG horn antenna penetration values begin at a value of

-10 dB at 1000 MHz and vary from -10 dB at 2000 MHz to -15 dB at 18,000 MHz. The

vertically polarized DRG horn antenna peaks at a penetration value of approximately -15 dB at 2000 MHz and varies from -15 dB to -30 dB from 2000 MHz to 18,000 MHz.

50
For the second set of data the antennas remained in the same location, but both receiving

antennas were positioned to point into the floor of the main passenger cabin. Beneath the main

passenger cabin floor is the cargo bay. This is position 3 (see Figure 67) as shown in Figure 66.

and results for this position are shown in Figure 67. Again, the horizontally polarized fields have

greater penetration than the vertically polarized fields and this penetration is most likely due to the main cabin windows. The horizontally polarized TEM horn antenna penetration values begin

around -20 dB at approximately 100 MHz and peaks at a value of-10 dB at around 1000 MHz.

The vertically polarized TEM horn antenna penetration values begin around -25 dB at 100 MHz

and peak at a value of-15 dB at 1000 MHz. The horizontally polarized DRG horn antenna

penetration begins at a value of-10 dB at 1000 MHz and varies slowly down to a value of

-20 dB at 18,000 MHz. The vertically polarized DRG horn antenna penetration peaks at a value

of approximately -15 dB at 1500 MHz and drops to -35 dB at 8000 MHz and then varies at values from -30 dB to -35 dB from 8000 MHz to 18,000 MHz.

Figure 64. Placement of receiving DRG and TEM horn antennas in the mid-passenger cabin for position 2.

51
-10 -J

COa -20 co

r^S3

l»C

-SO

0-

-40 ^

-50

Mid Passenger - 45 degrees

position 2 TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

4000 8000 12000

Frequency (MHz)

16000 20000

Figure 65. Penetration versus frequency for all antennas and polarizations for the transmitting tower placec

along the 45° extrapolation line and the receiving antennas placed in the mid-passenger cabin at position 2

Figure 66. Placement of receiving DRG and TEM horn antennas in the mid-passenger cabin for positions.

52
S -20

Mid Passenger - 45 degrees

position 3 TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

4000 8000 12000

Frequency (MHz)

16000 20000

Figure 67. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

along the 45° extrapolation line and the receiving antennas placed in the mid-passenger cabin at position 3.

6.3 Mid-Passenger Cabin Penetration Results

For the next series of measurements, the receiving TEM and DRG antennas were placed in the

mid-passenger cabin and were positioned as shown in Figures 68 and 69. The setup is the same

in both photos, but a photograph was taken from the front of the antennas and from behind the

antennas to show their proximity to the front and rear of the aircraft.

6.3.1 Single-Position Quadrant Measurements

Four transmitting locations were measured with the receiving antennas at the same location and

in the same orientation for all four measurements in the mid-passenger cabin. The transmitting

antennas were located at the 23.5 m (75 ft.) radius at the 0° position, the 90° position, the 135°

position and the 1 80° position, as shown by the red X's in Figure 70. We again notice that the

horizontally polarized fields tend to penetrate more easily into the aircraft than do the vertically

polarized fields, although the differences are not as large as in some of the previous

measurements. At the 0° position, for the transmitting antennas in the horizontal polarization,

the penetration values vary from -25 dB at 100 MHz to a peak value of-17 dB at around

2000 MHz. The penetration also varies from -20 dB to -30 dB from 2000 MHz to 18,000 MHz.

For the transmitting antennas in the the vertical polarization, the penetration values vary from

-25 dB to -30 dB across the frequency spectrum. At the 90° position, the vertical and horizontal

polarization results lie almost directly on top of each other. Penetration values rise to a peak

value of -10 dB around 2000 MHz down to -20 dB at 18,000 MHz. We measured

approximately the same behavior for the 135° position. At the 180° position the horizontally

53
polarized fields penetrate more easily at the lower frequencies up to about 12,000 MHz, and then

the values are only slightly above those of the vertically polarized fields. The highest penetration occurs for the horizontally polarized fields from 500 MHz to 1000 MHz at a value of -20 dB; it then drops to a value of -35 dB at 12,000 MHz, and is constant at a value of -35 dB from

12,000 MHz to 1 8,000 MHz. The maximum penetration for the vertically polarized fields occurs

at around 2000 MHz at a value of -30 dB;p it then drops to a value of -40 dB between

8000 MHz and 12,000 MHz and then increases to a value of -35 dB at 18,000 MHz. We moved

the tower approximately 0.3 m to the left and then took another set of measurements and notice

that the results are virtually the same as those from the 1 80° position. We see maximum

penetration into this aircraft at the measured angles of 90° and 135°. The minimum penetration occurs at the 1 80° position, and the penetration through the flight deck shows results between

these two extremes.

At the 90° position, from the previous set of measurements, we took a tight circular sweep

around this position to look at results and how they depend on the antenna pattern of both the

DRG horn antennas and the TEM horn antennas. While at the 90° position, we initially

boresighted the anteima at the midsection of the aircraft. We then moved the transmitting

antenna tower 45° degrees to the left and took another measurement; we then moved the tower

another 45° at this same 90° clock position to a 90° offset from boresight and then again with the

antennas facing 180° from boresight of the aircraft. The results of these measurements are shown in Figure 68. With the antenna boresighted at the aircraft, the vertically polarized and

horizontally polarized penetration values lie almost directly on top of each other. They rise to a peak value of-10 dB at around 2000 MHz, and down to -20 dB at 18,000 MHz. This

measurement taken at 90° is the same as in the previous section 6.3.1 . With the antenna pointing

45° to the left of the boresight position (pointing at the tail) we obtain the results shown in Figure

71. We immediately see two results: the first is the band-edge discontinuity between the results

of the vertically polarized TEM horn antenna and the DRG horn antenna. The second is the

large spike in the vertically polarized data that occurs at approximately 1 7,000 MHz. We can

speculate that this might be an ambient signal picked up only with the antennas in the vertical

polarization. At the 90° offset, we see dominant influences for vertically polarized antennas.

There is a band-edge discontinuity between the results for the TEM horn antennas and the DRG

horn antennas, and then a large signal drop in the 8000 MHz to 10,000 MHz frequency band.

Finally, as the antennas are pointed 1 80° away from the aircraft, we see a large discontinuity

between the horizontally and vertically polarized TEM horn antenna low-frequency band and the

horizontally and vertically polarized DRG horn antenna high-frequency band. This is most

likely due to small signal levels from the back-lobes of the antennas.

54
Figure 68. Placement of receiving DRG and TEM horn antennas in the

mid-passenger cabin for single-position quadrant measurements looking

toward front of aircraft.

Figure 69. Placement of receiving DRG and TEM horn antennas in the

mid-passenger cabin for single-position quadrant measurements looking

toward rear of aircraft.

55
Mid Section - degrees TEM Hpo: DRG - Hpol TEM - Vpol DRG - Vpol

n ' I ' r

4000 8000 12000 1600(1 20000

Frequency (MHz)

Mid Section - 90 degrees

(pointed al midsection) TEM - Hpol DRG - Hpol TEM - Vpol DRG - Vpol

4000 8000 12000 16000 2 Frequency (MHz)

Mid Section - I HO degrees TEM • Hpol DRG - Hpol TEM - Vpol DRG - Vpol

Mid Section - 1 80 degrees (move I ft) TEM - Hpol DRG - Hpol TEM - Vpol DRG - Vpol

8000 12000

Frequency (MHz)

T—'—

r

4000 8000 12000

Frequency (MHz)

Mid Section 135 degrees TEM - Hpol DRG • Hpol TEM - Vpol DRG Vpol

I

'

I

' ]

' I

' I 4000 8000 12000 16000 20000

Frequency (MHz)

Figure 70. Penetration versus frequency for all antennas and polarizations for the

transmitting tower moved around the aircraft at single positions in each quadrant. The

receiving antenna is in the mid-passenger cabin.

6.3.2 Rear Quadrant Sector Measurements

The receiving antennas remained in the same position as for the previous set of measurements.

The transmitting antenna tower was moved to positions around the rear quadrant of the aircraft

from 90° to 180°. Measurements were taken every 10° from 90° to 120° and from 150° to 180°

and then every 5° from 120° to 150°. These tests were designed to give us information on how

many positions around the aircraft are required to fully characterize the penetration [29]. Further

information is given in Appendix B. Based on a theoretical analysis for a single cut-plane, the

number of positions required to fully characterize the Bombardier Global 5000 at 1 GHz is 1 197,

[

56
Mid Sccoon - 90 degrees

(pointed al midsccnon) TEM - Hpol DRO - Hpol TEM - Vpol DRG Vpol

8000 I20O0

Frequency (MHz)

1 80 degree

offset

Mid Section - 90 degrees

(45 degrees ptd away from 737) TEM - Hpol DRG - Hpol TEM - Vpol DRG Vpol

T—'—

r

8000 12000

Frequency (MHz)

Mid Sccoon 90 degrees

( 18(1 degrees ofTscl) TEM - Hpol ORG- Hpol TEM - Vpol DRG - Vpol

Mid Section - 90 degrees (90 degrees offset) TEM - Hpol DRG - Hpol TEM - Vpol DRG - Vpol

81100 12000

Frequency (MHz,)

8000 12000 16000

Frequency (MHz)

Figure 71 . Penetration versus frequency for all antennas and polarizations for the transmitting tower

moved in a small circle at the 90° position. The receiving antenna is in the mid-passenger cabin.

at 5 GHz it is 5973, and at 1 8 GHz, the number of positions required to fully characterize the

aircraft increases to 21505 [31]. This is based on the equation

vV. 4ka + 2 for ka >\, (4)

where k is the propagation constant A: = 2;r / A , and a is the radius of the object. For the

Bombardier Global 5000, we used the largest dimension for the radius, which would be the

length of the aircraft. Since the number of positions required to fully characterize the aircraft are impractical to implement for testing, we wanted to know whether any major penetration points

would be missed, and thus we decided to sample at the positions given above.

The results for angular positions from 90° to 130° are shown in Figure 72. For the measurements

in general, we see that the horizontally polarized TEM horn antenna shows penetration values

that are lower than those for the vertically polarized TEM horn antenna. Also, there seems to be

a resonance that occurs at around 400 MHz for the horizontally polarized fields; we have seen

57
this in several other aircraft types. For the measurement at 90°, we see that at the higher

frequencies the traces for horizontally and vertically polarized antennas lie almost directly on top

of one another. There is a discontinuity between band edges at around 1 GHz that could have

something to do with antenna alignment, as discussed in the previous section. Penetration values

appear to average out around -20 dB across this bandwidth. Because these measurements were

taken at a later date than results shown in the previous measurements and with a different

system, we would expect the measurements to be the same only to within a specified uncertainty.

These uncertainties will be addressed at the end of this technical report. However, for

comparison, we introduce the measurement results from the previous section (6.3.1) into Figure

73. The plot on the left shows measurement results from October 2004, which are the same

results shown in Figure 72. The average value is about -20 dB across the frequency bandwidth.

The plot on the right shows the measurement results from October 2005, which shows that the

average value varies from -10 dB to -15 dB. Although these two results are different, we have

to remember that repeatability is a function of both the transmitting location on the outside of the

aircraft and the receiving location on the inside of the aircraft and the orientation of the receiving

or transmitting antennas. At the 1 00° position, we see a 1 dB to 2 dB difference at the band

edges and the penetration value seems to average around -22 dB across this bandwidth of

interest. For the 90°, 100° and 1 10° positions, there appears to be a slight peaking of values from

approximately 500 MHz to 1000 MHz for the vertically polarized antennas. At the 1 10°

position, the penetration values for the horizontally and vertically polarized antennas tend to overlap in the higher frequency band with an approximate average of -22 dB. For the angular

positions from 120° to 130°, the penetration values average out to around -20 dB and the

differences between the values for horizontally polarized and vertically polarized antennas are minimal.

Figure 74 shows the penetration results for angular positions from 135° to 180°. Again, in these

plots we see a resonance that occurs at around 400 MHz for the horizontally polarized TEM horn

antenna. Band edges tend to align to within 1 dB to 2 dB, and there is not much difference

between the horizontally and vertically polarized antennas until we reach 160° to 180°. The

average penetration value for 135° and 140° is around -20 dB to -22 dB. At 145° the average

penetration value has dropped to around -22 dB, and at 1 50° the average penetration value has

dropped to around -25 dB. For the 160° angular position, frequencies below 1000 MHz show

the same penetration values of around -30 dB, but above 1000 MHz, the horizontally polarized

antenna shows an average penetration value of approximately -25 dB and the vertically

polarized antenna shows an average penetration value of approximately -28 dB. At 170° the two

different polarizations split further, with results for the horizontally polarized antenna

maintaining an average penetration value of -25 dB, and those for the vertically polarized

antenna having an average penetration value around -35 dB. At the 180° position, the two

polarizations have greater differences in the high-frequency band and are now at approximately

-30 dB and -40 dB in the horizontal polarization and vertical polarization, respectively. For the

lower frequency band, these results compare to within 5 dB of those shown in Figure 75, and to within 5 dB to 7 dB in the upper frequency band.

58
(gp) UOIIEJIOUDJ

—\ ' T"

o o

(gp) uoireJi3U3j

OO

O

s § o • —

3

00c

c3

(gp) uonEnsusj

(gp) uonEj)3u3j

O

00

,o

a

-ac

C3

iJ -5

> i- co o

(Tt O

U -n c r

<L) (Ti a.

o

CnI l/~l t~- (N

(1> -1^n O(N

(gp) uonensusd

59
-10

-20

-30

-40

-50

Main Cabin - 90 degrees TEM - Hpoi

DRG - Hpol

TEM - Vpol

DRG - Vpol

Mid Section - 90 degrees

(pointed at midsection) TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

1000 2000

Frequency (MHz)

3000 1000 2000

Frequency (MHz)

3000

Figure 73. Comparison between Oct 2004 tests (left) and October 2005 tests (right) at the 90° position. The

tests on the left were taken with a system having a bandwidth of 6000 MHz and the tests on the right were

tai<^en with a system having a bandwidth of 1 8,000 MHz.

60
(gp) U011EI13U3d

61
Main Cabin - 180 degrees TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

1000 2000

Frequency (MHz)

-10 Mid Section - 1 80 degrees TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

3000 1000 2000

Frequency (MHz)

3000

Figure 75. Comparison between Oct 2004 tests (left) and October 2005 tests (right) at the 180° position. The tests on the left were taken with a system having a bandwidth of 6000 MHz and the tests on the right were taken with a system having a bandwidth of 18,000 MHz.

62
6.4 Intercompartmental Insertion Loss Measurements

Aircraft manufacturers are concerned with high-level RF signals entering aircraft compartments

where flight-sensitive equipment is installed. They will typically measure the penetration of

high-level fields into these compartments where aircraft control systems exist. Usually, the

receiving antenna is placed into the cavity along with a small stirrer and then the reverberant

fields are measured to obtain a time and spatial average of the fields over the volume of the

cavity. Because aircraft testing is time-consuming and expensive, typically only a few positions

are measured, and the cavity is assumed to exhibit reverberant behavior. If the cavity is assumed

to be reverberant, then statistically the electric field is uniform over the volume of that cavity.

To verify this assumption, NIST decided to measure the insertion loss between aircraft cavities

for several different positions without the use of mode-stirring/mode-tuning. The results are presented here. We have also included more information on statistics for the Bombardier Global

5000 and the Premier I A in Appendix C and numerical simulations for interior propagation

measurements for the 737-200 in Appendix D.

6.4.1 Main Cabin to Main Cabin

The DRG and TEM horn antennas were measured at various positions around the main cabin.

The DRG antenna positions were not measured at the same time as the TEM horn antenna

positions because only two channels were available from the VNA at any one time for the

internal configurations. In general, for each compartment-to-compartment measurement we tried to position them in approximately the same position for each of these runs.

6.4.1.1 Combined TEM horn antenna positions

Six positions were measured by use of the TEM horn antennas. For setup 1 , the measurement

was taken twice without repositioning antennas with the main cabin door open and closed.

Figure 76 shows all measurement results in the main cabin for the TEM horn antenna showing a maximum insertion loss of around -35 dB and a minimum insertion loss of around -75 dB.

Figures 77 shows the results for the measurement having maximum cabin insertion loss,

minimum insertion loss and two system noise-floor measurements. The first noise-floor

measurement was taken with the aircraft's Auxiliary Power Unit (APU) on and the second was

taken with the APU off.

Whisker-box plots are shown in Figure 78 for the following center frequencies, (1) 100 MHz, (2)

500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these plots are from a 200 MHz bandwidth around each center frequency. These plots show that the median

insertion loss for these frequencies have values from about -45 dB to -85 dB. The maximum

insertion loss for these frequencies is approximately -30 dB in a 200 MHz bandwidth around a center frequency of 1 500 MHz, and the minimum insertion loss is -11 8 dB in a 200 MHz

bandwidth around a center frequency of 100 MHz. Fifty percent of the data occurs in the light

blue and dark blue boxes in the 25^^ and 75^^ percent quartiles. The program used to process this

data does not give the distribution of points in the upper and lower tails of this data.

63
-30-1

-40-

-50

-60 ^

-70 -n

-80 -

-90

-100

Main Cabin to Main Cabin

- TEM - Setup 1 (door open)

- TEM - Setup 1

- TEM - Setup 2

- TEM - Setup 3

- TEM - Setup 4

- TEM - Setup 5

- TEM - Setup 6

I

^

\ 1000 2000

Frequency (MHz)

3000

Figure 76. Main cabin to main cabin TEM antenna data insertion

loss data at each of the six positions and one repeat position.

-90

100

-110 -

Mam Cabin to Main Cabin TEM - Setup 1 (door open)

• TEM - Setup 2 TEM - System NOISE (acu on)

• TEM - System NOISE (acu off)

-120

1000 2000 3000

Frequency (MHz)

Figure 77. Main cabin to main cabin TEM antenna data for the maximum insertion loss, the minimum insertion loss and two

noise measurements.

In reverberation chambers, common statistical distributions used to evaluate the cavity are the

chi-squared probability density function (j" pdf) and the chi-squared cumulative distribution

function (/ cdf). The/ pdffor all TEM horn anterma measurements is shown in Figure 79 and

the / cdffor all TEM horn anterma measurements is shown in Figure 80. The histogram in

Figure 79 consists of all points birmed into 1 dB bins (light-blue bins) and plotted against the

theoretical probability density function (dark-blue trace) and the average value of the theoretical

data (pink trace). The theoretical average value is around -38 dB. Figure 80 is the data (dark64
Figure 78. Whisker-box plots for all main cabin to main cabin insertion loss measurements of

the TEM horn antennas at several frequencies.

blue, solid trace) plotted against the theoretical cumulative distribution function. This plot shows

that the data does not tightly follow the theoretical cumulative distribution function. This does

not typically seem to be the case for the individual positions.

250

200

150

100 -

50 -

-

TEM

Main Cabin to Main Cabin

(all setups)

mijljljjl Binned Data ~ '^^ X" distribution Xvernae \ahie

-60 -50 -40 -30

Penetration Bin (dB) Figure 79. Chi-squared probability density function for all measurements in the main cabin to main cabin insertion loss measurements.

65
0.8 -

0.6 -

0.4 -I

0.2-

TEM

Main Cabin to Main Cabin

(all setups) — Mensiiied Data + f} dish ibiitioii

-70 -60 -50

Penetration Bin (dB)

Figure 80. Chi-squared cumulative density function for all measurements in the main cabin to main cabin insertion loss measurements.

6.4.1.1 Individual TEM horn antenna measurement positions

In this section each measurement position is individually analyzed. Figures 81 to 92 show a photograph of the measurement positions, a time-domain plot and a schematic of the inside of

the737-200 that indicates where the antennas were placed.

66
Figure 8 1 shows the placement for the transmitting and receiving TEM horn antennas in the

main cabin for setup 1 and measurements 1 and 2. The horizontally polarized 1 .2 m TEM horn

antenna was located in the rear of the aircraft on a piece of closed-cell foam and pointed toward

the back of the aircraft. The vertically polarized 36 cm antenna was located in the first-class

section of the aircraft and pointed toward the front of the aircraft. The antennas were not

boresighted and therefore no direct components exist in this measurement, as shown in the timedomain graph of Figure 82. Two measurements were taken, one with the main cabin passenger

door open and one with it closed. The graph in Figure 82 shows only minor differences exist

between having the door open or closed.

Figure 81 . Main cabin to main cabin TEM horn antenna setup 1

,

0.001

0.0005 -

-0.0005

-0.001

'JlMi«rtiW'M*^A<

Main Cabin to Main Cabin ~ TEM - Setup 1 __ TEM - Setup 1 (FD door open)

100 200 300 Time (ns) Figure 82. Main cabin to main cabin TEM horn

antenna setup 1, time-domain response.

67
Figure 83 shows the placement of the transmitting and receiving TEM horn antennas in the main

cabin for setup 2, measurements 1 and 2. The vertically polarized 1.2 m TEM horn antenna was

located in the rear of the aircraft on a piece of closed-cell foam centered over the aisle. The

vertically polarized 36 cm antenna was located in the first-class section of the aircraft toward the

front and was also placed on a piece of closed-cell foam centered over the aisle. The antennas were intentionally boresighted in this setup to help us understand how the direct component can

influence the statistics. A time-domain graph of this measurement is shown in Figure 84. The

time domain is used to help us understand relationship between the direct component and

reverberant fields. Figure 84 shows the waveform including the direct component (black trace),

and another waveform with the direct component gated out (red trace).

ol^ •»<mmms

1^ ,-

^ijjli '*'v^-^-

HHi.

Figure 83. Main cabin to main cabin TEM horn antenna setup.

M||^I'^AI(WH'v*^«*-**«'^—

Main Cabin to Main Cabin

- TEM - Setup 2 TEM - Setup 2

- No Direct Component

200 300 Time (ns) Figure 84. Main cabin to main cabin TEM horn

antenna setup 2,time-domain response.

68
Figure 85 shows the placement of the transmitting and receiving TEM horn antennas in the main

cabin for setup 3, measurements 1 and 2. The vertically polarized 1 .2 m TEM horn antenna was

left in the same location as for setup 2, which was on a piece of closed-cell foam centered over

the aisle at the rear of the aircraft. The 36 cm TEM horn antenna was located in an overhead

compartment in the first-class section of the aircraft and pointed toward the front of the aircraft. The overhead compartment door was open. The time-domain waveform is shown in Figure 86.

Figure 85. Main cabin to main cabin TEM horn antenna setup 3.

0.003

0.0025 ^

0.002

u 0.0015

|_ 0001

E< 0.0005 -

ca .§> on^ -0.0005

'Iflji^lillifM^'rim^

-0.001

-0.0015

-0.002

-0.0025

-0,003

Main Cabin to Main Cabin TEM - Setup 3

100 200 300 Time (ns)

Figure 86. Main cabin to main cabin TEM horn antenna setup 3, time-domain response.

69
Figure 87 shows the placement of the transmitting and receiving DRG horn antennas in the main

cabin for setup 4. The 1 .2 m TEM horn antenna was located in the rear of the aircraft on a piece

of closed-cell foam facing the passenger windows toward the front of the aircraft. The 36 cm

antenna was located in an overhead compartment in the first-class section of the aircraft and

pointed toward the front of the aircraft, as in setup 3. The compartment was partially closed.

The time-domain waveform is shown in Figure 88.

Figure 87. Main cabin to main cabin TEM hom antenna setup 4.

0.003

0.0025

0.002 -

<u 0.0015

•a3

"aE< 0.0005

.^

« -0.0005

I

-0.001 H

o^ -0.0015

-0.002

-0.0025

-0.003

'MWi^i^i^*»

Main Cabin to Main Cabin TEM - Setup 4 m

1 *• -;

100 200 300 Time (ns)

Figure 88. Main cabin to main cabin TEM hom

antenna setup 4, time-domain response.

70
Figure 89 shows the placement of the transmitting and receiving TEM horn antennas in the main

cabin for setup 5. The 1 .2 m TEM horn antenna was on a piece of closed-cell foam the rear of

the aircraft in the same configuration as for Setup 4. The vertically polarized 36 cm TEM horn

antenna was located on the floor the first-class section of the aircraft and pointed toward the side

of the aircraft. The time-domain waveform is shown in Figure 90.

B^ '- —' "^ 0mn

Figure 89. Main cabin to main cabin TEM horn antenna setup 5.

0.003

0.0025 H

0.002

u 0.0015

•o^ 0.001 H

E< 0.0005

ta

.2^ onI -0.0005

I

-0.001 o^ -0.0015

-0.002

-0.0025

-0.003

llmMjIlM^ —~~"'

Main Cabin to Main Cabin TEM - Setup 5

100 200 300 Time (ns)

Figure 90. Main cabin to main cabin TEM horn

antenna setup 5, time-domain response.

71
Figure 91 shows the placement of the transmitting and receiving TEM horn antennas in the main

cabin for setup 6, measurements 1 and 2. Both antennas were placed on the floor of the main

cabin. The horizontally polarized 1 .2 m TEM horn antenna was located in the rear of the aircraft

and pointed toward the front of the aircraft along the aisle. The vertically polarized 36 cm TEM

horn antenna was located on the floor just behind the first-class section of the aircraft and

pointed toward the rear of the aircraft. The time-domain waveform is shown in Figure 92.

Figure 91 . Main cabin to main cabin TEM horn antenna setup 6.

0.003 -

0.0025 -j

0.002 ^

<L, 0.0015 -

-aI 0.001 J

E

~ < 0.0005 -

(73 C

op 1 -0.0005 -

-0.001 —

-0.0015 -

-0.002 ^

-0.0025 ^

-0.003 —

1 1 kkM^^J^YM'^rti^-

Main Cabin to Main Cabin TEM - Setup 6

100 200 300 Time (ns)

Figure 92 Main cabin to main cabin TEM horn

antenna setup 6, time-domain response.

72
Figure 93 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 1 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 2 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the /'statistic. The difference between the

two means is also displayed. Finally, the x pdfand the /' cdfaxe plotted for each setup from

Figure 94 to Figure 97.

Setup 1

- door Setup 1 Setup 2 Setup 2 Setup 3 Setup 3 Setup 6 Setup 6 open - meas 1 - meas 2 - meas 1 - meas 2 - meas 1 Setup 4 Setup 5 - meas 2 - meas 1

0,

-10,

-20,

-30,

-40,

-50, -60

-70 -80

-90 100

00

00

00

00

00

tt T

Figure 93. Whisker-box plots for the TEM horn antennas for main cabin to main cabin insertion loss.

73
Table 1 . TEM horn internal cabin statistics for measurements from the main cabin to the main cabin. The

sample size was 321 points which were in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup Setup 1 Setup Setup Setup Setup

Setup

4

Setup

5

Setup Setup

1 door door 2 meas 2 meas 3 meas 3 meas 6 meas 6 meas

oj)en closed 1 2 1 2 1 2 Mean

(dB)

-63.99 -63.08 -44.98 -45.62 -53.09 -50.75 -57.75 -57.15 -51.08 -53.24

Median

(dB)

-63.11 -61.79 -45.12 -45.19 -51.43 -50.10 -57.09 -56.40 -50.51 -52.07

Standard

Deviation 5.28 5.98 4.64 5.60 5.58 4.65 4.53 5.04 5.15 6.08

(dB)

Minimum

(dB)

-85.79 -85.47 -64.56 -73.12 -78.71 -64.27 -70.59 -82.58 -78.92 -78.78

Maximum

(dB)

-54.35 -54.47 -37.31 -37.69 -44.19 -43.88 -48.90 -48.47 -41.73 -42.07

Table 2. TEM hom antenna internal cabin A^-distribution statistics for measurements from the main cabin to the main cabin.

Setup 1 door openSetup! door

closed

Setup 2 meas !Setup 2 meas 2Setup 3 meas !Setup 3 meas 2 Setup 4 Setup 5 Setup 6 meas 1

Setup 6 meas 2

Whisker-Box

Plot Mean (dB)

-63.99 -63.08 -44.92 -45.62 -53.09 - 50.75 -57.75 -57.15 -51.08 -53.24

X^ Mean (dB) -62.00 -6!. 00 -35.00 -34.00 -50.00 -47.00 -56.00 -62.00 -63.00 -59.00

A(dB) -1.00 -2.00 -!0.00 -!!.00 -3.00 -3.00 -2.00 +5.00 + 13.00 +6.00

74
-ac

a!

•T3Cacu

D.O

i^oo

-a

<U to ^ o^rt w o c c c E

03 o C c o

>: o

tJj 1- [- E

'R <ut ;

COO ,0

Q. '+» T3 ^ Q>m c 3 F c/) <i> u« -C 3 U <a

Hi

'i- E o

(\> ri 3

Q.3

suig JO jsqiuPN (ap)daD

75
ooa ^ c ' o2 CO o Z U

KT, c:

— ^s

lu 2 ^ H c ' O o c: ' s

suigjo J3qiun|\i (ep)da3 o

D.

T3O

Q.E - ' (U c 3 o si

CO

{/I 3 ?5 c Eo c r

nrt

n

O

C3 .C c

(33 E H 0)

_o

—

en (53 u

</-! Q.

ON 3

cu 01

c/l 3

OC -a

su|a JO J3qiun|\i (HP) JQD

76 i
suig JO jsqujnf^i (8P) JQD

suig JO jsqiunfvj

a.3

3

Q.3

_o o h- c

o a d

c/) to O c o CL n

JO

033 r

CT"

c/) CCr

J=

•^ U O

c s ^«

-ac5

3

c u. E

(ap) JQD

77
50-1

40

30

10

TEM

Main Cabin to Main Cabin

Setup 6

0.8

'

1

\

' !'

\

' \' \ ' [ -80 -70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

TEM

Mam Cabin to Main Cabin

Setup 6

0.6 -

0.4

0.2-

100 -90 -80 -70 -60 -50 -40

Penetration Bin (dB)

50

40

30

20

10-

TEM

Main Cabin to Main Cabin

Setup 6 - m2

{'i %

i r

;

/' i 1 y 1'

-80 -70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

1

'

I -90 -80 -70 -60 -50 -40

Penetration Bin (dB)

Figure 97. Statistical analysis for TEM horn antenna, setup 6-measurement 1 , and setup 6, measurement 2, for main cabin to main cabin insertion loss.

78
6.4.1.3 Combined DRG horn antenna positions

Six positions were measured, with one repeat measurement for two of the positions. The

antennas were not moved for the reposition, the data were just retaken. Figure 98 shows results

for all measurements in the main cabin for the TEM horn antenna showing a maximum insertion

loss of around -30 dB and a minimum insertion loss of around -65 dB. Figure 99 show results

for the measurement of maximum cabin insertion loss, the minimum insertion loss, and two

system noise floors. One noise-floor measurement was taken with the DRG antennas positioned

in setup 1, and the other noise-floor measurement was taken with the antennas positioned in

setup 4.

For the DRG horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz,

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions, as shown in

Figure 97. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a

total of 2247 points will be in the statistical bandwidth. The results from the 900 MHz set and

the 1000 MHz for the DRG horn antenna sets may not be completely statistically independent

but it was important to stay away from the band edges of the measurement; and it was also

important to include enough information for reliable processing. Figure 100 shows the median

insertion loss across the frequency bandwidth range from about -40 dB to -50 dB. The

maximum insertion loss for these frequencies is approximately -21 dB in a 200 MHz bandwidth

around a center frequency of 1500 MHz; and the minimum insertion loss is -100 dB in a 200 MHz bandwidth around a center frequency of 1 000 MHz.

The/ pdffor all TEM horn anterma measurements is shown in Figure 101, and the/' cdffor all TEM horn antenna measurements is shown in Figure 102. The histogram in Figure 101 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -38 dB. Figure 102 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function.

79
-o

-30

-40

-50

-60

-70

-80-

-90

-100

Cargo Bay

DRG- Setup7(meas 1) DRG-Setup7(meas2)

DRG - Setup 8 DRG - Setup 9 DRG -Setup 10 DRG - Setup 1

1

DRG -Setup 12

1000 2000

Frequency (MHz)

3000

Figure 98. Main cabin to main cabin DRG antenna insertion loss data at each of the six positions and one repeat position.

-30

-40

-50-

-60 -

-70

S -80 -

-90 -

-100

-no

-120

DRG - Setup 8 DRG -Setup 10 NOISE

DRG-Setup lONOISWmeL 4) jL

'

\

'

\

^

1 1000 2000 3000

Frequency (MHz)

Figure 99. Main cabin to main cabin DRG antenna data for the maximum insertion loss, the minimum insertion loss, and two

noise measurements.

80
0.00

-20.00

-40.00

-60.00

-80.00

100.00 ^

Group 1 - Group 2

900 MHz GHz

Group 3 - Group 4 - 2 Group 5

-

1.5 GHz GHz 2.5 GHz

T

T

Figure 100. Whisker-box plots for all main cabin to main cabin insertion

loss measurements of the DRG horn antennas at several frequencies.

250

DRG

Main Cabin to Main Cabin 200 —I *^" setups)

£ 150

100

50

v^-i -f-^-i^

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

-10

Figure 101 . Chi-squared probability density function for all setups in the main cabin to main cabin insertion loss measurements.

81
0.8 -.

0.6

QU

0.4

0.2

DRG

Main Cabin to Main Cabin

(all setups)

-60 -50 -40

Penetration Bin (dB) 20

Figure 102. Chi-squared cumulative density function for all setups in the main cabin to main cabin insertion loss measurements.

6.4.1.4 Individual DRG horn antenna positions

A photograph for each DRG antenna to DRG antenna measurement position, its associated timedomain waveform, and a schematic showing the antenna positions inside the aircraft is shown

from Figure 103 to Figure 1 14. The time-domain waveforms provide information for any direct

antenna coupling components that may exist and the reverberant decay characteristics of the

cavity-to-cavity interaction.

82
Figure 103 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 7, measurements 1 and 2. Measurement 2 is a repeat measurement; the

antennas were not moved. Unfortunately, this is the only photograph we have and it is out of

focus. One antenna was vertically polarized and located in the rear of the aircraft on a piece of

closed-cell foam centered over the aisle. The other antenna was located in the first-class section

of the aircraft toward the front and was also placed on a piece of closed-cell foam centered over

the aisle in the vertical polarization. The antennas were intentionally boresighted in this setup to help us understand how the direct component can influence the statistics. Figure 104 is a timedomain graph showing a measurement with the direct antenna coupling component (black trace)

and without the direct antenna coupling component with only the reverberant fields (red trace).

Figure 1 03. Main cabin to main cabin DRG hom antenna setup 7.

0.005

J

-0.001 a

fe -0002 - z

-0.003

-0.004

-0.005

Main Cabin to Main Cabin DRG - Setup 7 DRG - Setup 7 - No direct component

40 120 160 200 Time (ns) Figure 104. Main cabin to main cabin DRG hom antenna

setup 7, time-domain response.

83
Figure 105 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 8. One antenna was horizontally polarized and located in the rear of the

aircraft on a piece of closed-cell foam pointing toward the back of the aircraft. The other,

vertically polarized antenna was located in the first-class section of the aircraft and pointed

toward the front of the aircraft. The antennas were not boresighted, and therefore no direct

components exist in this measurement, as shown in the time-domain graph of Figure 106.

Figure 105. Main cabin to main cabin DRG horn antenna setup 8.

0.001

<u 0.0005

-n3

5.E<

a

c

ou

00

-0.0005

-0.001

i|l|*4# ».)Hli«».iH<Mt .

Main Cabin to Main Cabin DRG - Setup !

100 200 300 Time (ns)

Figure 106. Main cabin to main cabin DRG horn

antenna setup 8, time-domain response.

84
Figure 107 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 9. One vertically polarized antenna was located in the rear of the aircraft on

a piece of closed-cell foam centered over the aisle in the same position as in setup 7. The other

antenna was located in an overhead compartment in the first-class section of the aircraft and

pointed toward the front of the aircraft. The compartment was left open. The time-domain graph

is shown in Figure 108.

Figure] 07. Main cabin to main cabin DRG horn antenna setup. 9

0.001

u 0.0005

-0.0005

-0.00

Itlb^

Main Cabin to Main Cabin DRG - Setup 9

100 200 300 Time (ns)

Fieure 1 08. Main cabin to main cabin DRG horn

85
Figure 1 09 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 10, measurements 1 and 2. One vertically polarized antenna was located in

the rear of the aircraft on a piece of closed-cell foam centered over the aisle, as in setup 9. The

other antenna was located in an overhead compartment in the first-class section of the aircraft

and pointed toward the front of the aircraft, but the overhead compartment door was then closed.

The time-domain graph is shown in Figure 110. By comparing Figure 108 and Figure 1 10 we

can see there is little difference in amplitude between closing the overhead compartment and

leaving it open.

11^i

A

^^B

1 1

mtfi

1 / V

Figure 1 09. Main cabin to main cabin DRG hom antenna setup 10.

0.001

u 0.0005 -

-0.0005

-0.001

Main Cabin to Main Cabin DRG - Setup 1

100 200 300 Time (ns)

Figure 1 1 0. Main cabin to main cabin DRG hom

antenna setup 10, time-domain response.

86
Figure 1 1 1 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 1 1 . One vertically polarized antenna was located in the rear of the aircraft on a piece of closed-cell foam pointing toward the center and outside of the aircraft. The other

vertically polarized antenna was located on the floor the first-class section of the aircraft and

pointed toward the outside of the aircraft. The time-domain graph is shown in Figure 1 12.

Figure 111. Main cabin to main cabin DRG hom antenna setup

0.001

0.0005

-0.0005

-0.001

Mi||h^^

Main Cabin to Main Cabin DRG - Setup 1

1

00 200 Time (ns) 300

Figure 1 12. Main cabin to main cabin DRG hom

antenna setup 1

1

, time-domain response.

87
Figure 1 1 3 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 12. Both antennas were placed on the floor of the main cabin. One

horizontally polarized antenna was located in the rear of the aircraft and pointed toward the front

of the aircraft along the aisle. The other vertically polarized antenna was located on the floor just

behind the first class section of the aircraft and pointed toward the rear of the aircraft. The

antennas were not boresighted, and therefore no direct components exist in this measurement as shown in the time-domain graph of Figure 1 14.

Figure 113. Main cabin to main cabin DRG

horn antenna setup 1 2.

0.0015

0.001 -

0.0005

-0.0005

-0.001

-0.0015

oi

**Mi*wMain Cabin to Main Cabin DRG -Setup 12

200 300 Time (ns)

Figure 1 14. Main cabin to main cabin DRG horn antenna setup 1 2, time-domain response.

88
A statistical analysis is presented in the next few graphs. A whisker-box plot is shown for each

DRG horn antenna in Figure 1 15, and Table 3 shows the mean value, the median value, the

standard deviation, the maximum value, and the minimum value. The statistics for each setup were taken over a 200 MHz bandwidth (equivalent to 321 data points) centered around a frequency of 1000 MHz. The chi-squared /' /?6//"and the/' ci^statistical descriptions are shown

in Figures 1 16 to Figure 117, and Table 4 compares the mean of general statistical analysis, the

mean from the analysis of the/ distribution, and the difference between these two means.

Setup 7

- Setup 7- Setup 10 Setup 10

0.00 -

Meas 1 Meas 2 Setups Setup 9 - Meas 1 - Meas 2 Setup 1

1

Setup 12

1 1 1

-10.00

-20.00

-30.00 -

-40.00

-50.00

1 B1

!!

T

T _~ T T

i

r

-60.00 -

-70.00

- - ^^H

- - ^-

1

-80.00 -

-90.00

-100.00

Figure 1 15. Whisker-box plots for the DRG horn antennas for setups 7 to 10. These

data are from measurements of main cabin to main cabin insertion loss.

89
Table 3. DRG horn internal cabin statistics for measurements from the main cabin to the main cabin.

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 7 meas 1Setup? meas 2

Setup 7 no

direct

Setup 8 Setup 9

Setup

10

Setup

1 redo

Setup

11

Setup

12

Mean

(dB)

-37.85 -36.40 -42.44 -56.92 -46.98 -46.25 -44.46 -47.41 -41.10

Median

(dB)

-36.69 -35.12 -40.71 -56.47 -45.89 -44.76 -43.76 -46.72 -39.90

Standard

Deviation 6.25 6.19 5.07 5.19 5.63 5.42 5.03 5.50 5.73

(dB)

Minimum

(dB)

-57.95 -61.68 -66.28 -100.92 -68.21 -70.77 -66.72 -76.71 -62.97

Maximum

(dB)

-29.15 -27.83 -36.44 -48.30 -38.34 -36.37 -35.71 -38.49 -31.16

Table 4. DRG horn antenna internal cabin X--distribution statistics for measurements from the main cabin to the main cabin.

Setup 7 meas 1Setup? meas 2Setup ? no

direct Setup 8 Setup 9 Setup 10 Setup 10 redo Setup 1

1

Setup 12

Whisker-Box

Plot Mean (dB)

-37.85 -36.40 - 42.44 -56.92 - 46.98 - 46.25 - 44.46 -47.41 -41.10

}P Mean (dB) -35.00 -31.00 -41.00 -57.00 - 44.00 - 43.00 - 43.00 - 44.00 -33.00

A(dB) -3.00 -4.00 - 1.00 >+1.00 -3.00 -2.00 - 1.50 -3.00 -7.00

90
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93
6.4.2 Main Cabin to Flight Deck

The DRG and TEM horn antennas were measured at various positions between the main cabin

and flight deck. In general, for each compartment-to-compartment measurement, we tried to position them in approximately the same position for each of these runs.

6.4.2.1 Combined DRG horn antenna positions

Four positions were measured for the DRG antenna type with a repeat measurement with the

flight deck to main cabin door closed for positions 1 and 3. Figure 1 19 shows all measurement

results for the DRG horn antenna showing a maximum insertion loss of around -50 dB and

minimum insertion loss of around -65 dB. Figure 120 shows the results for the measurement

having maximum cabin insertion loss, minimum insertion loss, and two system noise floor

measurements. There were no noise-floor measurements taken with the DRG horn antennas; the

TEM horn antenna data were used for the noise floor. The noise-floor measurement shown by

the gold trace was the system noise floor taken by putting a 50 ohm load on the receiving side of

the system. The purple trace is the ambient noise floor taken by putting the 50 ohm load on the

transmitting side and looking for the ambient that enters the receiving antenna. Both were

averaged over a 200 MHz bandwidth.

Whisker-box plots are shown in Figure 121 for the following center frequencies, (1) 100 MHz,

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these

plots are from a 200 MHz bandwidth around each center frequency. These plots show that the

median insertion loss for these frequencies has values from about -50 dB to -60 dB. The

maximum insertion loss for these frequencies is approximately -44 dB in a 200 MHz bandwidth

around a center frequency of 1500 MHz. and the minimum insertion loss is -100 dB dB in a 200 MHz bandwidth around a center frequency of 1 00 MHz.

94
oa

-40

-50-

-60

-70

-80

-90

-100

Main Cabin to Flight Deck

DRG - Setup 1 DRG - Setup 1 (FD door closed) DRG - Setup 2 DRG - Setup 3 DRG - Setup 3 (FD door closed) DRG - Setup 4

I

'

\ 1000 2000

Frequency (MHz)

3000

Figure 1 19. Main cabin to flight deck DRG antenna insertion loss data at each of the four positions, and two repeat measurements

with the flight deck door closed. The/ pdffor all DRG horn antenna measurements is shown in Figure 122, and the x" cdffor all TEM horn antenna measurements is shown in Figure 123. The histogram in Figure 122 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -53 dB. Figure 123 is the data (dark-blue, solid trace) plotted

-40-1

-50-

-60-

CQ -70

-80

-90

-100

-110 -

-120

Flight Deck DRG - Setup 3 DRG - Setup 2 TEM - System NOISE TEM - Ambient NOISE

1000 2000

Frequency (MHz)

3000

Figure 120. Main cabin to flight deck DRG horn antenna data for the maximum and minimum insertion loss, and two TEM horn

antenna noise measurements.

95
0.00

-

-10.00

-

-20.00

-

-30.00 -

-40.00 -

-50.00

-

-60.00

-

-70.00

-

-80.00

-

-90.00

-

-100.00

^

Group 1 - 900 MHzGroup 2

- GHz

1 Group 3 - 1.5 Group 4-

GHz GHz

2 Group 5 - 2.5

GHz

1 1 1 1 1

• T 1 J

, EH 1 1^

'-

. -L J'

Figure 121. Whisker-box plots of all main cabin to flight deck insertion-loss

measurements for the DRG horn antennas at several frequencies.

against the theoretical cumulative distribution function. This plot shows that the data do not

tightly follow the theoretical cumulative distribution function. This does not typically seem to be

the case for the individual positions.

200

160-

120

E

80

40 -

j^.4

DRG

Main Cabin to Flight Deck

(all setups)

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

-20

Figure 122. Chi-squared probability density ftinction for all setups in the main cabin to flight deck insertion-loss measurements.

96
+

DRG

Main Cabin to Flight Deck

(all setups)

-70 -60

Penetration Bin(dB)

Figure 123. Chi-squared cumulative density function for all setups in the main cabin to flight deck insertion loss measurements.

6.4.2.2 Individual DRG horn antenna measurement positions

In this section each measurement position from the main cabin to the flight deck is individually

analyzed. Figures 124 to 131 show photographs of the locations of the antennas in the flight

deck and the main cabin, a time-domain plot, and a schematic of the inside of the 737-200 that

indicates where the antennas were placed.

97
Figure 1 24 shows the placement for the transmitting and receiving DRG horn antennas in the

main cabin for setup 1, measurements 1 and 2. The flight deck door was open for measurement 1 and closed for measurement 2. One horizontally polarized antenna was located in the rear of the

aircraft on the floor of the main passenger cabin. The other antenna was located in the pilot's seat in the flight deck of the aircraft and pointed toward the ceiling. The graph in Figure 125

shows there is a slight difference between having the door open or closed, noticeable at the

beginning of the waveform; however, the decay of the fields seem to be the same.

dLEDLULi

Figure 124. Main cabin to flight deck DRG horn antenna setup.

<|HM|lHHi)l.c< » 1

1

Main Cabin to Flight Deck DRG - Setup I DRG - Setup 1 (FD door closed)

100 200 Time (ns)

300

UPv '>'Li

Figure 125. Main cabin to flight deck DRG horn

antenna setup 1 , time-domain response.

98
Figure 126 shows the placements of the transmitting and receiving DRG horn antennas in the

main cabin for setup 2, measurements 1 and 2. One horizontally polarized antenna was located

in the rear of the aircraft on the floor of the main passenger cabin. The other horizontally

polarized antenna was located in the co-pilot's seat in the flight deck of the aircraft and pointed

toward the left side. A time-domain graph of this measurement is shown in Figure 127.

Figure 126. Main cabin to flight deck DRG horn antenna setup 2.

0.001

0.0005

-0.0005

-0.001

-*ll»lll#lfl*»*^l*'tll I

Main Cabin to Flight Deck DRG - Setup 2

100 200 Time (ns)

300

Figure 127. Main cabin to flight deck DRG horn antenna setup 2, time-domain response.

99
Figure 128 shows the placement of the transmitting and receiving DRG horn antennas in the

main cabin for setup 3, measurements 1 and 2. For this position we also took one measurement

with the flight deck door open and one with the flight deck door closed. One vertically polarized

antenna was located in the first class section over a seat. The other horizontally polarized

antenna was located in the co-pilot's seat in the flight deck of the aircraft and pointed toward the

left side. The time-domain waveform is shown in Figure 129. The time-domain graphs show

only slight differences between the two measurements.

Figure 128. Main cabin to flight deck DRG horn antenna setup 3.

0.001

00005

-0.0005

-0.001

H|»»>»»*w -'

Main Cabin to Flight Deck

- DRG-Senjp3 _ DRG - Setup 3 (FD door closed)

100 200 Time (ns)

300

Figure 129. Main cabin to flight deck DRG

horn antenna setup 3, time-domain response.

100
Figure 130 shows the placements of the transmitting and receiving DRG horn antennas in the

main cabin for setup 4. One vertically polarized antenna was located in the first class section over a seat. The other horizontally polarized antenna was located on the floor by the co-pilot's

seat and pointed toward the front of the aircraft. The compartment was partially closed. The

time-domain waveform is shown in Figure 131.

Figure 1 30. Main cabin to flight deck DRG horn antenna setup 4.

0.001

«j 0.0005

-0.0005

-0.001

*W<l

'

Mam Cabin to Flight Deck DRG - Setup 4

100 200 300 Time (ns) Figure 131. Main cabin to flight deck DRG horn

antenna setup 4, time-domain response.

101
Figure 132 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 5 summarizes the statistics of each setup for the whisker-box plots, including the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 6 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the /'statistic. The difference between the

two means is also displayed. Finally, the x pdfand the x^ cdfare plotted for each setup in

Figure 133 and Figure 134.

Setup 1- Setup 1- Seti4)3- Seti4)3-

dooropen door closed Setup 2 door closed door open Setup 4

T

Figure 132. Whisker-box plots for the DRG horn antennas for main cabin to flight deck insertion loss.

102
Table 5. DRG horn internal cabin statistics for measurements from the main cabin to the flight deck.

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 1 Setup 1 Setup 2 Setup 3 Setup 3 Setup 4

door open door closed meas 1 door open door closed

Mean (dB) -58.37 -59.78 -63.98 -54.08 -53.07 -55.21

Median

(dB)

-57.11 -59.02 -62.06 -52.87 -51.89 -53.95

Standard

Deviation 5.28 4.88 6.25 6.70 6.08 6.35

(dB)

Minimum

(dB)

-81.94 -85.55 -82.42 -77.53 -74.91 -77.17

Maximum

(dB)

-50.31 -49.82 -54.90 -44.03 -43.64 -44.83

Table 6. DRG horn antenna internal cabin X- - distribution statistics for measurements from the main

cabin to the flight deck.

Setup 1 Setup 1 Setup 2 Setup 3 Setup 3 Setup 4 door open door closed meas 1 door open door closed

WhiskerBox Plot -58.37 -59.78 -63.98 -54.08 -53.07 -55.21 Mean (dB)

^Mean

(dB)

-57.00 -55.00 -58.00 -54.00 -52.00 -52.00

A(dB) -1.00 -5.00 -6.00 <-1.00 - 1.00 -3.00

103
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suig JO jsquinf,! (ap)ja3

104
su|g JO JsquiriN (ap) JQD

105
6.4.2.3 Combined TEM horn antenna positions

Six positions were measured for the TEM horn antenna type, with a repeat measurement for

position 8. The antennas were not moved for the reposition, the data were just retaken. Figure

135 shows resuhs for all measurement results in the main cabin for the TEM horn antenna

showing a maximum insertion loss of around -50 dB and a minimum insertion loss of around

-75 dB. Figure 136 show results for the maximum cabin insertion loss measurement, the

minimum insertion loss measurement, and two system noise floors.

For the TEM horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz,

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions, as shown in

Figure 97. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a

total of 2247 points will be in the statistical bandwidth. The results from the 900 MHz set and

the 1 000 MHz for the TEM horn antenna sets may not be completely statistically independent,

but it was important to stay away from the band edges of the measurement, and it was also

important to include enough information for reliable processing. Figure 137 shows the median

insertion loss across the frequency bandwidth range from about -65 dB to -90 dB. The

maximum insertion loss for these frequencies is approximately -50 dB in a 200 MHz bandwidth

around a center frequency of 1 500 MHz, and the minimum insertion loss is -140 dB in a 200 MHz bandwidth around a center frequency of 1 000 MHz.

The/ pdffor all TEM horn antenna measurements is shown in Figure 138, and the/' cdffor all TEM horn antenna measurements is shown in Figure 139. The histogram in Figure 138 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -62 dB. Figure 139 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function.

106
-40

-50

^ -60 m•o

-70

-80 ^

-90

-100

TEM - Setup 6 TEM - Setup 7 TEM - Setup 8 (meas I) TEM - Setup 8 (meas 2) TEM - Setup 9 TEM -Setup 10 ~1 ' T"

1000 2000

Frequency (MHz)

3000

Figure 135. Main cabin to flight deck TEM antenna insertion loss data at each of the six positions and one repeat measurement at position 8.

-40-1

-50

CD

-60

-70

-80

-90

100

-110 -

-120

TEM - Setup 5 TEM - Setup 9 TEM - System NOISE TEM - Ambient NOlSEf

1000 2000

Frequency (MHz)

3000

Figure 136. Main cabin to flight deck TEM horn antenna data for the maximum insertion loss, the minimum insertion loss, and two

noise measurements.

107
Group 1 - Group 2 - Group 3 - 1 Groiq) 4 -

100 MHz 500 MHz GHz 1.5 GHz

0.00 ;

-20.00 ^

-40.00 i

-60.00

-80.00 1

100.00 ^

•120.00 :

140.00 J

160.00

Group 5 - 2 GHz

Group 6

-

2.5 GHz

Figure 1 37. Whisker-box plots for all main cabin to flight deck insertion loss measurements

of the TEM horn antennas at several frequencies.

200

160

,1 120

80

40

J! i

^

-<

/

i

i^

.f

N..

TEM

Main Cabin to Flight Deck

(all setups)

1

' T"

-70 -60 -50 -40 -30

Penetration Bin (dB)

-20 10

Figure 138. Chi-squared probability density function for all setups in the main cabin to flight deck insertion loss measurements.

108
0.8

0.6

TEM

Main Cabin to Flight Deck

(all setups)

0.4

0.2 -

-70 -60

Penetration Bin (dB)

Figure 139. Chi-squared cumulative density function for all setups in the main cabin to flight deck insertion loss measurements.

6.4.2.4 Individual TEM horn antenna positions

Figures 140 to Figure 149 include a photograph for each TEM antenna measurement location

from the main cabin to the flight deck, its associated time-domain waveform, and a schematic

showing the antenna positions inside the aircraft.

109
Figure 140 shows the placement of a transmitting 1.2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 5. The

vertically polarized 1.2 m TEM horn antenna was located in the rear of the aircraft across the

center aisle. The horizontally polarized 36 cm TEM horn antenna was located on the floor by the

co-pilot's seat and pointed toward the front of the aircraft. Figure 141 is a time-domain graph

showing a measurement with the direct antenna coupling component (black trace) and without

the direct antenna coupling component with only the reverberant fields (red trace).

Figure 140. Main cabin to flight deck TEM horn antenna setup 5.

0.001 -

0.0005 -

-0.0005

||jl\^||VH'//ft**H*'AMain Cabin to Flight Deck TEM - Setup 5

100 200 Time (ns)

Figure 141. Main cabin to flight deck TEM horn antenna setup 5, time-domain response.

110
Figure 142 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn anterma in the flight deck for setup 6. The

vertically polarized 1 .2 m TEM horn antenna was located in the rear of the aircraft across the

center aisle. The horizontally polarized 36 cm TEM horn antenna was located in the co-pilot's

seat and pointed toward the left side of the aircraft. Figure 143 is a time-domain graph of the

measurement.

^

JS^ ( _^IB^^_^^

^Q9 '^'^^^IBHH

1

- ^^

1

Figure 142. Main cabin to flight deck TEM horn antenna setup 6.

0.001

u 0.0005

-0.0005 -

-0.001

*/,#>i»HWi^^^

Main Cabin to Flight Deck TEM - Setup 6

100 200 300 Time (ns) Figure 143. Main cabin to flight deck TEM horn antenna setup 6, time-domain response.

I i

OiJ riTf

ill
Figure 144 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 7. The

horizontally polarized 1 .2 m TEM horn antenna was placed on the floor in the aisle at the rear of

the aircraft. The vertically polarized 36 cm TEM horn antenna was located in the co-pilot's seat and pointed toward the left side of the aircraft. Figure 145 is a time-domain graph of the

measurement.

Figure 144. Main cabin to flight deck TEM horn antenna setup 7.

0,001

0.0005

-0.0005

-0.001

^|iWttW^**^'**^'»

Main Cabin to Flight Deck TEM - Setup 7

100 200 Time (ns) 300

Figure 1 45. Main cabin to flight deck TEM horn antenna setup 7, time-domain response.

112
Figure 146 shows the placement of a transmitting 1.2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 8,

measurements 1 and 2. The horizontally polarized 1 .2 m TEM horn antenna was placed on the

floor in the aisle at the rear of the aircraft. The horizontally polarized 36 cm TEM horn antenna

was located in the co-pilot's seat and pointed toward the ceiling of the aircraft. Figure 147 is a time-domain graph of the measurement and a repeat measurement for the flight deck.

Figure 146. Main cabin to flight deck TEM horn antenna setup 8.

0,001

o 0.0005

-0.0005

-0.001

|ifi*i^^Mwwp^T**---

Main Cabin to Flight Deck — TEM - Setup 8 — TEM - Setup 8 - repeat

100 200 Time (ns) 300

Figure 147. Main cabin to flight deck TEM horn antenna setup 8, time-domain response.

113
Figure 148 shows the placement of a transmitting 1.2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 9. The

horizontally polarized 1.2 m TEM horn antenna was placed facing into the floor in the aisle at the rear of the aircraft. The 36 cm TEM horn antenna was located in the pilot's seat and pointed

upward toward the ceiling. Figure 149 is a time-domain graph of the measurement.

Figure 148. Main cabin to flight deck TEM horn antenna

setup 9 and setup 10. The 1 .2 m TEM horn antenna was in the horizontal polarization for setup 9 and in the vertical polarization for setup 1 0.

^I^^tll' l ' "

Main Cabin to Flight Deck TEM - Setup 9 TEM -Setup 10

~1

100 200 Time (ns)

Figure 149. Main cabin to flight deck TEM horn antenna

setup 9 and setup 10, time-domain response.

114
Figure 150 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 7 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 8 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the /^statistic. The difference between the

two means is also displayed. Finally, the /" pdfand the x cdfaiQ plotted for each setup in Figure

148, Figure 149, and Figure 150.

Setup 8 - Setup 8

-

Setup 5 Setup 6 Setup 7 Meas 1 Meas 2 Setup 9 Setup 10

0.00

-20.00

-40.00

-60.00

-80.00

100.00

^

-L +

T

^

Figure 1 50. Whisker-box plots for the TEM horn antennas for main cabin to flight deck insertion loss.

115
Table 7. TEM horn internal cabin statistics for measurements from the main cabin to the flight deck. The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 5 Setup 6 Setup 7 Setup 8 meas 1

Setup 8 meas 2 Setup 9 Setup 1

Mean

(dB)

-62.60 -62.22 -67.16 -62.26 -62.15 -71.29 -67.83

Median

(dB)

-62.12 -61.94 -67.22 -62.13 -61.45 -70.40 -66.61

Standard

Deviation 5.36 4.74 6.06 4.61 5.36 4.92 4.89

(dB)

Minimum

(dB)

-84.56 -83.75 -90.19 -80.67 -78.64 -93.48 -85.75

Maximum

(dB)

-52.30 -54.00 -55.35 -53.65 -51.72 -64.00 -60.19

Table 8. TEM horn antenna internal cabin X^ - distribution statistics for measurements from the main

cabin to the flight deck.

Setup 5 Setup 6 Setup 7 Setup 8 meas 1

Setup 8 meas 2

Setup 9 Setup 1

WhiskerBox Plot Mean

- 62.60 - 62.22 -67.16 - 62.26 -62.15 -71.29 -67.83

(dB)

A^Mean

(dB)

- 60.00 -57.00 -63.00 - 62.00 -60.00 -71.00 - 69.00

A(dB) -2.00 -5.00 - 4.00 >- 1.00 - 2.00 >- 1.00 + 2.00

116
-

TEM

Cabin

to

Flight

Setup

7 -

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117
E 2 3

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-an

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118
50

40

CQ

E

20

10 -

TEM

Main Cabin to Flight Deck

Setup 1 0^

rt

l^ \

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

1 -1

0.8

0.6

TEM

Main Cabin to Flight Deck

Setup 10

D

U

0.4 -

0.2-

-80 -70

Penetration Bin (dB)

-20 -10

50

Figure 153. Statistical analysis for TEM horn antenna, setup 10, for main cabin to flight deck insertion loss.

119
6.4.3 Main Cabin to Cargo Bay

The DRG and TEM horn antennas were measured at various positions between the main cabin

and cargo bay. An RF cable was run from the VNA in the main cabin through a hole drilled into

the floor of the main passenger cabin into the cargo bay. In general, for each compartment-tocompartment measurement we tried to position them in approximately the same position for each

of these runs.

6.4.3.1 Combined DRG horn antenna positions

Four positions were measured for the DRG antenna type. No repeat measurements were

completed in this compartment-to-compartment measurement. Figure 1 54 shows all measurement results for the DRG horn antenna showing a maximum insertion loss of around

-30 dB and minimum insertion loss of around -55 dB. Figure 155 shows the results for the

measurement having maximum cabin insertion loss, minimum insertion loss and two system

noise-floor measurements. The noise-floor measurement shown by the brown trace was the

system noise floor taken by putting a 50 ohm load on the receiving side of the system. The green

trace is the ambient noise floor taken by putting the 50 ohm load on the transmitting side and

looking for the ambient signals that enter the receiving antenna. Both results were averaged by

se of a 200 MHz bandwidth.

Whisker-box plots are shown in Figure 156 for the following center frequencies, (1) 100 MHz,

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these

plots are from a 200 MHz bandwidth around each center frequency. The plots show the median

insertion loss for these frequencies range from about -41 dB to -48 dB. The maximum value for

these frequencies is approximately -26 dB in a 200 MHz bandwidth around a center frequency

of 1000 MHz, and the minimum insertion loss is -89 dB in a 200 MHz bandwidth around a

center frequency of 900 MHz.

120
-30

-40-

-50 -

OQ

-a^ -60 H

-70-

-80

-90-

-100

Main Cabin to Cargo Bay

DRG - Setup 1 DRG - Setup 2 DRG - Setup 5 DRG - Setup 6

1000 2000

Frequency (MHz)

3000

Figure 154. Main cabin to cargo bay DRG antenna insertion loss data at each of the four positions.

1 1 The x^ pdffor all DRG horn antenna measurements is shown in Figure 1 57 and the /' cdffor all DRG horn antenna measurements is shown in Figure 158. The histogram in Figure 157 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

-30

-40

-50

-60

-70

-80

-90

-100

-110

-120

Cargo Bay

DRG - Setup DRG - Setup 2 DRG - Ambient NOISE Floor DRG - System NOISE Floor

1000 2000

Frequency (MHz)

3000

Figure 1 55. Main cabin to cargo bay DRG antenna data for the maximum insertion loss, the minimum insertion loss, and two noise

measurements.

121
theoretical average value is around -39 dB. Figure 158 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function. This plot shows that the data do not

tightly follow the theoretical cumulative distribution function. This does not typically seem to be

the case for the individual positions.

n (''\r\

Group 1 - 900 l\IHzGroup 2

-

1 GHz

Group 3

-

1.5 GHz

Group 4 - 2 GHz

Group 5

- 2.5 GHz

u.uu

-10.00 ~

1 1 1 1

-20.00 -

-30.00

in nn

T m— a ^^ -4U UU

-50.00 -

-60.00 -

^" -

-70.00 -

-80.00 •

i-

-90 00 -

100 00 -

Figure 1 56. Whisker-box plots of all main cabin to cargo bay insertion loss measurements

for the DRG horn antennas at several frequencies.

120 -I

80

40

DRG

Main Cabin to Cargo Bay

(all setups) /

'

ffll

| T ^

f^ Ml

70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB) Figure 157. Chi-squared probability density function for all measurements of insertion loss in the main cabin to cargo bay.

122
0.8

0.6

DRG

Mam Cabin to Cargo Bay

(all setups)

0.4

0.2-

-60 -50 -40

Penetration Bin (dB)

-20

Figure 158. Chi-squared cumulative density function for all measurements of insertion loss in the main cabin to cargo bay.

6.4.3.2 Individual DRG horn antenna measurement positions

In this section each measurement position from the main cabin to the cargo bay is individually

analyzed. Figures 1 59 to 166 show a photograph of the locations of the antennas in the flight

deck and the main cabin, a time-domain plot, and a schematic of the inside of the 737-200 that

indicates where the antennas were placed.

123
Figure 159 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the cargo bay for setup 1 . One vertically polarized antenna

was located in the rear of the aircraft on top of the seats of the main passenger and pointed

toward the front of the aircraft. The other vertically polarized antenna was located on an

insulated cooler and pointed toward the avionics bay. Figure 160 is a time-domain graph of the

measurement for the cargo bay.

i

Figure 1 59. Main cabin to cargo bay DRG horn antenna setup 1 .

Cargo

Bay

0.003 -1

0,0025

002 -

00015

001 -

0005 -

-0 0005

-0 001

-0 0015

-0.002

-0.0025

-0.003

-||#»»^*'»»"'

Main Cabin to Cargo Bay DRG - Setup I

100 200 Time (ns) 300

Figure 160. Main cabin to cargo bay DRG horn antenna setup 1, time-domain response.

124
Figure 161 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the cargo bay for setup 2. One vertically polarized antenna

was located in the in the first-class section on top of the seats of the main passenger cabin and

pointed toward the front of the aircraft. The other, vertically polarized, antenna was located on

an insulated cooler and pointed toward the avionics bay. Figure 162 is a time-domain graph of

the measurement for the cargo bay.

Figure 161 . Main cabin to cargo bay DRG horn antenna setup 2. -V- 2 Cargo

I Bay

»"iW'">'»-'

Main Cabin to Cargo Bay DRG - Setup 2

200 300 Time (ns)

Figure 162. Main cabin to cargo bay DRG horn antenna setup 2, time-domain response.

125
Figure 1 63 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the cargo bay for setup 5. One vertically polarized antenna

was located in the in the first class section on top of the seats of the main passenger cabin and

pointed toward the front of the aircraft. The other horizontally polarized antenna was located on

an insulated cooler and pointed toward the avionics bay. Figure 164 is a time-domain graph of

the measurement for the cargo bay.

Figure 1 63. Main cabin to cargo bay DRG horn antenna setup 5. \-

0.003

0.0025 -

0.002

0.0015 H

0.001

0.0005

-0.0005 —

-0.00

-0.0015 -

-0.002 -

-0.0025 -

-0.003

i Cargo

I Bay

4>ti)K#»4|t.t».

Main Cabin to Cargo Bay DRG -Setup 5

100 200 Time (ns) 300

Figure 1 64. Main cabin to cargo bay DRG horn

antenna setup 5, time-domain response.

126
Figure 165 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the cargo bay for setup 6. One vertically polarized antenna

was located in the rear of the aircraft on top of the seats of the main passenger cabin and pointed

toward the front of the aircraft. The other, horizontally polarized, antenna was located on an

insulated cooler pointing toward the avionics bay. A time-domain graph of the measurement for

the cargo bay is shown in Figure 166.

\

,*~»t^ >

Figure 165. Main cabin to cargo bay DRG horn antenna setup 6.

0.003 -I

0.0025

0.002

<u 0.0015 -

o3= 0.001 -

E< 0.0005 a^1/3 "S -0,0005 —

I

-0.001 -

o

•^ -0.0015

-0.002 H

-0.0025

-0.003

Cargo

Bay

Main Cabin to Cargo Bay DRG - Setup 6

100 200 300 Time (ns)

Figure 166. Main cabin to cargo bay DRG horn

antenna setup 6, time-domain response.

127
Figure 167 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 9 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 1 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the/ statistic. The difference between the

two means is also displayed. Finally, the/ pdfand the/ cdfaiQ plotted for each setup in Figure

168 and Figure 169.

Figure 1 67. Whisker-box plots for the DRG horn antennas for main cabin to cargo bay insertion loss.

128
Table 9. DRG Horn internal cabin statistics for measurements from the main cabin to the cargo bay.

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 1 Setup 2 Setup 5 Setup 6

Mean (dB) -48.06 - 39.46 - 40.68 -48.83

Median (dB) -47.31 - 38.62 -38.71 - 47.45

Standard

Deviation (dB)

4.10 7.13 6.01 7.20

Minimum (dB) - 74.68 -77.41 -73.48 - 78.66

Maximum (dB) -41.62 - 26.80 -34.17 -38.63

Table 10. DRG horn antenna internal cabin X^ - distribution statistics for measurements

from the main cabin to the cargo bay.

Setup 1 Setup 2 Setup 5 Setup 6

Whisker-Box Plot

Mean (dB)

-48.06 - 39.46 -40.68 -48.83

r~ Mean (dB) - 45.00 -35.00 -38.00 -45.00

A(dB) -3.00 -4.00 - 1.00 -3.00

129
CO ^3 Cfl ifi O m

c c o o o S •c

(L> c «

u c Q. >^

c« X) OvO

' O

OB^

kJo

COo

in

a.

T3c

CO

n.

Q.3

a:

CO

00

3

iZ

suig JO jaquintvl (gp) JQD

130
50 -1

40 DRG

Main Cabin to Cargo Bay

Setup 6

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0.8 -

0.6 -

CQ•o

u.Q

0.4 -

0.2-

-60 -40

Penetration Bin (dB)

Figure 169. Statistical analysis for DRG horn antenna, setup 6, for main cabin to cargo bay insertion loss.

131
6.4.3.3 Combined TEM horn antenna positions

Six positions were measured for the TEM horn antenna. Figure 1 70 show results for all measurements in the main cabin for the TEM horn antenna showing a maximum insertion loss of

around -35 dB and a minimum insertion loss of around -60 dB. Figure 171 shows a measurement of the maximum cabin insertion loss, the minimum insertion loss, and two system

noise floors.

For the TEM horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz,

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions, as shown in

Figure 172. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a

total of 2247 points will be in the statistical bandwidth. These plots show the average insertion

loss for these frequencies range from about -45 dB to -90 dB. The maximum insertion loss for

these frequencies is approximately -35 dB in a 200 MHz bandwidth around center frequencies of

1000 and 2000 MHz, and the minimum insertion loss is -135 dB in a 200 MHz bandwidth

around a center frequency of 1 00 MHz.

The x" pdffor all TEM horn antenna measurements is shown in Figure 1 73, and the /' cdffor all TEM horn antenna measurements is shown in Figure 174. The histogram in Figure 173 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -46 dB. Figure 174 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function.

132
-30 ^

o

-90

-100

Cargo Bay

TEM - Setup 1 TEM - Setup 2 TEM - Setup 3 TEM - Setup 4 TEM - Setup 5 TEM - Setup 6

1000 2000

Frequency (MHz)

3000

Figure 1 70. Main cabin to cargo bay TEM antenna insertion loss data at each of the six positions.

T3

-30 -]

-40 -

-50 -

-60

-70 2 -80 -

-90

Cargo Bay

TEM - Setup 1 TEM - Setup 4 TEM - System NOISE Floor

1000 2000

Frequency (MHz)

3000

Figure 171. Main cabin to cargo bay TEM antenna data for the maximum

insertion loss, the minimumt insertion loss, and a noise measurement.

133
0.00

-20,00

-40 00

-60,00

-80.00

100.00

120 00

140.00

160 00

Group 1 Group 2 - Group 3 - Group 4 - Group 5 - Group 6 - 100^fflz500MHz 1 GHz 1 5 GHz 2 GHz 2.5 GHz

it ±

Figure 172. Whisker-box plots of all main cabin to cargo bay insertion-loss measurements

for the TEM horn antennas at several fi"equencies.

100

80

S 60

E

40

20-

TEM

Main Cabin to Cargo Bay

(ail setups)

J

^°^M

t

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

-20 -10

Figure 173. Chi-squared probability density function for all measurements of insertion loss in the main cabin to cargo bay.

134
0.8

0.6

a.DU

0.4

0.2

1 1 1 1 1 n 1 1 1 1 11 m "—

I

\ 1-

-60 -50 -40

Penetration Bin (dB) Figure 174. Chi-squared cumulative density function for all measurements of insertion loss in the main cabin to cargo bay.

6.4.3.4 Individual TEM horn antenna positions

A photograph for each TEM antenna measurement location from the main cabin to the cargo

bay, its associated time-domain waveform, and a schematic showing the antenna positions inside

the aircraft is shown from Figure 175 to Figure 186.

135
Figure 1 75 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 1, measurements 1 and 2. The vertically polarized 1.2 m TEM horn antenna was located in the rear of the aircraft positioned across the seats, and pointed toward the front of the aircraft and out the

windows. The vertically polarized 36 cm TEM horn antenna was located on an insulated cooler

and pointed toward the avionics bay. A time-domain graph is shown in Figure 176.

Figure 175. Main cabin to cargo bay TEM horn antenna setup 1

.

\

0.003

0.0025

0.002

0.0015

0.001

0.0005

-0.0005 •

-0.001

-0.0015

-0.002

-0.0025

-0.003

I Cargo

' Bay

r^tf^MM^'

Main Cabin to Cargo Bay TEM - Setup I

100 200 Time (ns)

Figure 1 76. Main cabin to cargo bay TEM horn antenna setup 1 , time-domain response.

136
Figure 1 77 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 2. The

vertically polarized 1.2 m TEM horn antenna was located in the first-class section of the aircraft

positioned across the seats, and pointed toward the front of the aircraft. The vertically polarized

36 cm TEM horn antenna was located on an insulated cooler and pointed toward the avionics

bay. A time-domain graph is shown in Figures 178.

Figure 1 77. Main cabin to cargo bay TEM horn antenna setup 2.

J Cargo

f Bay

MM^\<^ft<t^<»M*f''^rf-'-^—

r

Main Cabin lo Cargo Bay TEM - Setup 2

300 Time (ns)

Figure 1 78. Main cabin to cargo bay TEM horn antenna setup 2, time-domain response.

137
Figure 179 shows the placement of a transmitting 1.2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 3. The

vertically polarized 1 .2 m TEM horn antenna v^as located in the first-class section of the aircraft

and pointed down into the cargo bay. This was to see whether there was strong coupling with a

directed measurement. The vertically polarized 36 cm TEM horn antenna was located on an

insulated cooler and pointed toward the avionics bay. A time-domain graph is shown in Figure

180.

Figure 179. Main cabin to cargo bay TEM horn antenna setup 3.

Pf#t*«'

Main Cabin to Cargo Bay TEM - Setup 3

100 200 300 Time (ns) Figure 1 80. Main cabin to cargo bay TEM horn antenna setup 3, time-domain response.

138
Figure 181 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 4. The

vertically polarized 1 .2 m TEM horn antenna was located in the first-class section of the aircraft

and pointed down into the cargo bay. This was to see whether there was strong coupling with a

directed measurement. The horizontally polarized 36 cm TEM horn antenna was located on an

insulated cooler and pointed toward the avionics bay. A time-domain graph is shown in Figure

182.

Figure 181. Main cabin to cargo bay TEM horn antenna setup 4.

0.003 -|

0.0025 -

0.002

0.0015 -

0.001 -

0.0005

-0.0005 -

-0.001 -

-0.0015

-0.002

-0.0025

-0.003

Main Cabin to Cargo Bay TEM - Setup 4

100 200 300 Time (ns)

Figure 1 82. Main cabin to cargo bay TEM horn

antenna setup 4, time-domain response.

139
Figure 183 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 5. The

horizontally polarized 1.2 m TEM horn antenna was located in the first-class section of the

aircraft and pointed down into the cargo bay. The horizontally polarized 36 cm TEM horn

antenna was located on an insulated cooler and pointed toward the avionics bay. A time-domain

graph is shown in Figure 184.

Figure 1 83. Main cabin to cargo bay TEM horn antenna setup 5.

0003

0.0025

0.002

0.0015

0.001

0.0005

-0.0005

-0.001

-0.0015

-0.002 H

-0.0025

-0.003

;t

^ Cargo

5 Bay

^-aWB',, #if*W*^**

Main Cabin to Cargo Bay TEM - Setup 5

100 200 300 Time (ns)

Figure 1 84. Main cabin to cargo bay TEM hom

antenna setup 5, time-domain response.

140
Figure 185 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 6. The

vertically polarized 1.2 m TEM horn antenna was located in the rear of the aircraft positioned

across the seats, and pointed toward the front of the aircraft and out the windows. The

horizontally polarized 36 cm TEM horn antenna was located on an insulated cooler and pointed

toward the avionics bay. A time-domain graph is shown in Figure 1 86.

Figure 1 85. Main cabin to cargo bay TEM horn antenna setup 6.

0.003

0.0025 -

0.002

0,0015 -

0.001

0.0005

-0.0005

-0.001

-0 0015

-0.002

-0.0025 H

-0.003

Cargo

T

Bay

Pptt

Main Cabin to Cargo Bay TEM - Setup 6

100 200 Time (ns) 300

Figure 1 86. Main cabin to cargo bay TEM horn antenna setup 6, time-domain response.

141
Figure 187 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 1 1 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 12 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the/' statistic. The difference between the

two means is also displayed. Finally, the/ pdfdx\di the/ cdfare plotted for each setup in Figure

188, Figure 189, and Figure 190.

Setup 1 Setup 1

- Meas 1 - Repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6

0.00

-10.00

-20.00

-30.00

-40.00

-50.00

-60.00

-70.00

-80.00

-90.00

Figure 1 87. Whisker-box plots for the TEM horn antennas for main cabin to cargo bay insertion

loss for individual setups.

tii

142
Table 1 1 . TEM Horn internal cabin statistics for measurements from the main cabin to the cargo bay.

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 1 Setup 1 repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6

Mean(dB) - 56.03 -56.17 - 46.94 - 43.05 -47.12 - 40.68 -53.88

Median (dB) - 54.99 -55.47 -45.88 -41.45 -46.52 -38.71 -52.80

Standard

Deviation (dB)

6.78 5.55 6.41 5.22 6.01 6.01 6.04

Minimum (dB) -81.06 - 82.68 - 73.65 - 66.62 -75.27 -73.48 -78.61

Maximum (dB) - 44.43 -45.74 -37.02 -34.91 - 36.68 -34.17 -44.39

Table 12. TEM horn antenna internal cabin X- - distribution statistics for measurements from the

main cabin to the cargo bay.

Setup 1 Setup 1 repeatSetup 2 Setup 3 Setup 4 Setup 5 Setup 6

Whisker-Box

Plot Mean - 56.03 -56.17 - 46.94 -43.05 -47.12 - 40.68 -53.88

(dB)

vP Mean (dB) -51.00 -45.00 -36.00 - 44.00 - 50.00 -38.00 - 54.00

A(dB) -5.00 -11.00 -11.00 + 1.00 + 3.00 -3.00 < 1.00

143
suig JO jaquinisi (eP) dOD

Q.3

-oc

n.3

CC

a> rn E

v; -a ^^ v C3 c <U CD OL. o a o "O r-~ c c 03 D- n.3

1)Cc

<-> c

a- COco

.x: o 2oc. c/ o c/5

c/l ' o

C/5

—

>>

C

C3

O ^ c

CO

d

m dJ ^ 3c

CJ

c/5

m C/3 o C3 X)o o 03 GO ' C o6 CO 00 tj ' o

(U

r

OJD X>m

u- o

suig jo isquini^i HP) iOD

144
15 ^

(3

^^

^"

I " "X

' *T= - T^ ¥

c

i

' 1' 1' 1 "^ ^

suig JO iaquintsi 8P) JQD

O

00

o

a.

-a

a.

55

3

00

suigjo jaquinN (aP) iQO

145
3U -

TEM

Main Cabin to Cargo Bay

Setup 6 40-

30 -

20 - \

10 - i>

f\ prS r>^

/ V — ^-r^ -H—

1

' 1 1 -80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

-10

0.8 -

QU

TEM

Main Cabin to Cargo Bay

Setup 6

-60 -50

Penetration Bin (dB) Figure 1 90. Statistical analysis for TEM horn antenna, setup 6, for main cabin to cargo bay insertion loss.

146
6.4.4 Main Cabin to Avionics Bay

The DRG and TEM horn antennas were measured at various positions between the main cabin

and cargo bay. An RF cable was run from the main passenger cabin through the hole in the floor

of the main passenger cabin and through a hole in the wall from the cargo bay to the avionics

bay. In general, for each compartment-to-compartment measurement we tried to position the

antennas in approximately the same position for each of these runs.

6.4.4.1 Combined DRG horn antenna positions

Four positions were measured for the DRG antenna type. No repeat measurements were

completed in this compartment-to-compartment measurement. Figure 191 shows all measurement results for the DRG horn antenna showing a maximum insertion loss of around

-30 dB and and minimum insertion loss of around -55 dB. Figure 192 shows the results for the

measurement having maximum cabin insertion loss, minimum insertion loss and two system

noise-floor measurements. The noise-floor measurement was averaged by use of a 200 MHz

bandwidth.

Whisker-box plots are shown in Figure 193 for the following center frequencies, (1) 100 MHz,

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these

plots are from a 200 MHz bandwidth around each center frequency. The plots show the median

insertion loss for these frequencies have values from about -55 dB to -59 dB. The maximum

value for these frequencies is approximately -32 dB in a 200 MHz bandwidth around center

frequencies of 1000 MHz and 1500 MHz, and the minimum insertion loss is -98 dB in a 200 MHz bandwidth around center frequencies of 1500 MHz and 2500 MHz.

147
-30

-40

-50

•a- -60-

o

-J

-70

-80 -

-90

-100

Main Cabin to Avionics Bay

DRG - Setup 1 DRG - Setup 2 DRG - Setup 3 DRG - Setup 4

1000 2000

Frequency (MHz)

3000

Figure 191 . Main cabin to avionics bay DRG antenna insertion loss data at each of the four positions.

The /' pdffor all DRG horn antenna measurements is shown in Figure 1 94 and the / cdffor all DRG horn antenna measurements is shown in Figure 195. The histogram in Figure 194 contains

all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -39 dB. Figure 195 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function. This plot shows that the data do not

-30 -n

-40

-50

-60 -

o

-J

-70

•2 -80

CD ^ -90

-100

-110

-120

Main Cabin to Avionics Bay

DRG - Setup 4 DRG - Setup 2 DRG - NOISE Floor (Cargo Bay to Avionics Bay)

1000 2000

Frequency (MHz)

3000

Figure 192. Main cabin to avionics bay DRG horn antenna

data for the maximum insertion loss, the minimum insertion

loss, and two noise measurements.

148
tightly follow the theoretical cumulative distribution function. This does not typically seem to be

the case for the individual positions.

Group 1 - Group 2

900 MHz 1 GHz

Group 3 - Group 4 - Group 5

-

1.5 GHz 2 GHz 2.5 GHz

0.00

-20.00

-40.00

-60.00

-80.00

100.00

120.00

T T +

Figure 193. Whisker-box plots of all main cabin to avionics bay insertion loss measurements for the DRG horn antennas at several frequencies.

120-1

80

CQo

40

DRG

Main Cabin to Avionics Bay

(all setups) Li\

^-^]iX-W

I

-80 -70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

Figure 194. Chi-squared probability density function for all DRG

measurements of insertion loss in the main cabin to avionics bay.

149
1 -1

0.8

0.6-

0.4 -

0.2-

DRG

Main Cabin to Avionics Bay

(all setups)

+

+

-80 -70 -60 -50

Penetration Bin (dB)

-40 -30

Figure 195. Chi-squared cumulative density function for all DRG

measurements of insertion loss in the main cabin to avionics bay.

6.4.4.2 Individual DRG horn antenna measurement positions

In this section each measurement position from the main cabin to the avionics bay is individually

analyzed. Figures 196 to 203 show a photograph of the locations of the antennas in the flight

deck and the main cabin, a time-domain plot, and a schematic of the inside of the 737-200 that

indicates where the antennas were placed.

150
Figure 1 96 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the avionics bay for setup 1 , measurements with the

avionics bay door open and closed. One vertically polarized antenna was located in the rear of

the aircraft on top of the seats of the main passenger cabin and pointed toward the front of the

aircraft. The other vertically polarized antenna was located on an insulated cooler and pointed

toward the fi-ont of the aircraft. A time-domain graph of the measurement for the cargo bay is shown in Figure 197.

Figure 196. Main cabin to avionics bay DRG horn antenna setup 1.

0.003 -

0.0025 —

0.002 -|

0.0015 -|

0.001 -

0.0005 —

-0.0005 -

-0.001 —

-0 0015

-0.002

-0.0025

Main Cabin to Avionics Bay DRG - Setup 1

-0.003

100 200 Time (ns) 300

Figure 197. Main cabin to avionics bay DRG horn antenna setup 1 , time-domain response.

151
Figure 198 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the avionics bay for setup 2, measurements with the

avionics bay door open and closed. One vertically polarized antenna was located in the rear of

the aircraft on top of the seats of the main passenger cabin and pointed toward the front of the

aircraft. The horizontally polarized other antenna was located on an insulated cooler and pointed

toward the fi-ont of the aircraft. A time-domain graph of the measurement for the cargo bay is shown in Figure 199.

Figure 198. Main cabin to avionics bay DRG horn antenna setup 2.

0.003 -|

0.0025 -

0.002 -

0.0015 -

0.001

0.0005 -

-0.0005 -

-0.001

-0 0015

-0.002

-0.0025

-0.003

-4«-

Main Cabin to Avionics Bay DRG -Setup 2

1 ^ T"

100 200

Time(ns)

300

Figure 199. Main cabin to avionics bay DRG horn

antenna setup 2, time-domain response.

[Avionics

41T7] nT( ^9S

152
Figure 200 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the avionics bay for setup 3, measurements with the

avionics bay door open and closed. One vertically polarized antenna was located in the rear of

the aircraft on top of the seats of the main passenger cabin and pointed toward the front of the

aircraft. The other antenna was located on an insulated cooler and pointed upward toward

avionics bay door. A time-domain graph of the measurement for the cargo bay is shown in

Figure 201.

Figure 200. Main cabin to avionics bay DRG horn antenna setup 3.

0.003

0.0025

0.002

00015 -

0.001

0.0005

-0.0005

-0.001

-0.0015

-0.002

-0.0025

-0.003

.. 4|i^lhiin.»

Main Cabin to Avionics Bay DRG -Setup 3

100 200 300

Wi

H iijiiiy uU CJiiJ

k I 1

1 Avionics C

J Bay

3UiJ fjTy

Time (ns)

Figure 201 . Main cabin to avionics bay DRG horn

antenna setup 3, time-domain response.

153
Figure 202 shows the placement of a transmitting DRG horn antenna in the main passenger cabin

and a receiving DRG horn antenna in the avionics bay for setup 4, measurements with the

avionics bay door open and closed. One horizontally polarized antenna was located in the first class section on top of the main passenger seats. The antenna pointed toward the front of the

aircraft. The other antenna was located on an insulated cooler and pointed upward toward

avionics bay door. A time-domain graph of the measurement for the cargo bay is shown in

Figure 203.

Figure 202. Main cabin to avionics bay DRG horn antenna setup 4.

0.003 -|

0.0025 -

0.002 -

<u 0.0015 - t 0.001 -

E< 0.0005 -

i> -

"S -0 0005 -

I

-0.001 -

o^ -0.0015 -

-0.002 -

-0.0025

-0.003

Main Cabin to Avionics Bay DRG - Setup 4

100 200 300 Time (ns)

Figure 203. Main cabin to avionics bay DRG horn

antenna setup 4, time-domain response.

s (

154
Figure 204 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 13 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 14 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the /' statistic. The difference between the

two means is also displayed. Finally, the /' /»Jfand the/^ cdfare plotted for each setup in Figure

202.

Figure 204. Statistical analysis for DRG horn antenna for main cabin to avionics bay

insertion loss for individual setups.

155
Table 13. DRG Horn internal cabin statistics for measurements from the main cabin to the avionics bay.

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 1 Setup 2 Setup 3 Setup 4

Mean (dB) - 59.00 -60.41 -56.53 -42.89

Median (dB) -57.86 - 59.25 -55.37 -41.51

Standard

Deviation (dB)

5.16 5.78 5.23 6.43

Minimum (dB) - 80.88 - 92.70 - 75.04 -69.71

Maximum (dB) -51.04 -53.00 -48.70 -33.68

Table 14. DRG horn antenna internal cabin X^ - distribution statistics for measurements

from the main cabin to the avionics bay.

Setup 1 Setup 2 Setup 3 Setup 4

Whisker-Box

Plot Mean (dB)

- 59.00 -60.41 -56.53 -42.89

^Mean (dB) - 62.00 -57.00 - 52.00 -37.00

A(dB) + 3.00 -3.00 -4.00 -6.00

156
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6.4.4.3 Combined TEM horn antenna positions

Three positions were measured for the TEM horn antenna type. Figure 206 shows resuhs for all measurement results in the main cabin for the TEM horn antenna showing a maximum insertion

loss of around -35 dB and a minimum insertion loss of around -60 dB. Figure 207 show results

for the maximum cabin insertion loss measurement, the minimum insertion loss measurement,

and a system noise floor taken from the cargo bay to the avionics bay.

For the TEM horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz,

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions as shown in

Figure 208. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a

total of 2247 points will be in the statistical bandwidth. The maximum insertion loss for these

frequencies is approximately -41 dB in a 200 MHz bandwidth around a center frequency of

1000 MHz, and the minimum insertion loss is -156 dB in a 200 MHz bandwidth around a center

frequency of 1 00 MHz.

The X pdfiotx all TEM horn antenna measurements is shown in Figure 20, and the x cdfiox all TEM horn antenna measurements is shown in Figure 210. The histogram in Figure 209 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -46 dB. Figure 210 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function.

158
CQ-a

o

-J

-30

-40

-50 -

-60

-70 -

-80

-90 -

-100

TEM - Setup 4 TEM - Setups (meas 1) TEM - Setup 5 (meas 2)

1000 2000 3000

Frequency (MHz)

Figure 206. Main cabin to avionics bay TEM antenna insertion loss data at each of the three positions, with two additional

measurements.

m

o

-J

1000 2000

Frequency (MHz)

3000

Figure 207. Main cabin to avionics bay TEM horn anterma

data for the maximum insertion loss, the minimum insertion

loss, and two noise measurements.

159
0.00

-20.00 -

-40.00 -

-60.00

-80.00

•100.00

•120.00

•140.00

•160.00 -

•180.00

Group 1 - GroLq3 2- Group 3 - 1 Groi4)4-1.5 Group 5 - 2 Group 6 - 2.5 100 MHz 500 MHz GHz GHz GHz GHz

1

Figure 208. Whisker-box plots of all main cabin to avionics bay insertion loss measurements

for the TEM horn antennas at several frequencies.

160

120

c5

£

3Z

80 -

40-

-80

1 i

1

;' •

- ,1 / ^

^ J

1 1

TEM

Main Cabin to Avionics Bay

(all setups)

%

-70 -60 -50 -40 -30

Penetration Bin (dB)

-20 -10

Figure 209. Chi-squared probability density function for all TEM

measurements of insertion loss in the main cabin to avionics bay.

160
0.8 TEM

Main Cabin to Avionics Bay

(all setups)

0.6

CQ-a

u.Q

0.4-

0.2 -

Penetration Bin (dB)

Figure 210. Chi-squared cumulative density function for all TEM

measurements of insertion loss in the main cabin to avionics bay.

6.4.4.4 Individual TEM horn antenna positions

A photograph for each TEM antenna measurement location from the main cabin to the cargo

bay, its associated time-domain waveform, and a schematic showing the antenna positions inside

the aircraft is shown from Figure 21 1 to Figure 216.

161
Figure 2 1 1 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn anterma in the avionics bay for setup 1 , for

measurements with the avionics bay door open and closed. The vertically polarized 1 .2 m TEM

horn antenna was located in the rear of the aircraft across the seats and pointed forward toward

the windows. The vertically polarized 36 cm TEM horn antenna was located on an insulated

cooler and pointed toward the front of the aircraft. A time-domain graph of the measurement is shown in Figure 212.

3 Avionics

1 Bay

Figure 211. Main cabin to avionics bay TEM horn antenna setup 1

.

0.003

0.0025

0.002

00015

0.001

0.0005

-0,0005

-0,001

-0.0015

-0.002 -\

-0.0025

-0.003

Main Cabin to Avionics Bay TEM - Setup 1 (avionics bay door closed) TEM - Setup I (avionics bay door open)

' <i l4t»%»m«»>lrf

100 200 300 Time (ns)

Figure 212. Main cabin to avionics bay TEM horn antenna setup 1 , time-domain response.

162
Figure 213 shows the placement of a transmitting 1 .2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the avionics bay for setup 4. The

horizontally polarized 1.2 m TEM horn anterma was located in the first-class section on top of

the main passenger seats. The 36 cm TEM horn antenna was located on an insulated cooler and

pointed upward toward avionics bay door. A time-domain graph of the measurement is shown in

Figure 214.

Figure 213. Main cabin to avionics bay TEM horn antenna setup 4.

g Avionics

I Bay

0.003 —

0.0025

0.002

0.0015

0.001

0.0005

-0.0005 -

-O.OOI

-0.0015

-0.002

-0.0025

P»^4'>WvrfM..

-0.003

Main Cabin to Avionics Bay TEM - Semp 4

100 200 300 Time (ns)

Figure 214. Main cabin to avionics bay TEM horn

antenna setup 4, time-domain response.

163
Figure 215 shows the placement of a transmitting 1.2 m TEM horn antenna in the main

passenger cabin and a receiving 36 cm TEM horn antenna in the avionics bay for setup 5,

measurements 1 and 2. The 1 .2 m TEM horn antenna was located on the floor in the rear of the

aircraft and pointed forward down the aisle. The 36 cm TEM horn anterma was located on an

insulated cooler and pointed upward toward the avionics bay door. A time-domain graph of the

measurement is shown in Figure 216.

3 Avionics

I Bay

Figure 2 1 5. Main cabin to avionics bay TEM horn antenna setup 5.

0.003

0.0025

0.002

00015

0.001

0.0005 —

I

-nirtHyrtW'*fJ|M'^"**'***~

-0.0005 -

-0.001

-0.0015 -

-0.002

-0.0025

-0.003

Main Cabin to Avionics Bay — TEM - Setup 5 (meas 1

)

— TEM - Setup 5 (meas 2)

100 200 300 Time (ns)

Figure 2 1 6. Main cabin to avionics bay TEM horn

antenna setup 5, time-domain response.

164
Figure 217 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 15 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 16 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the/" statistic. The difference between the

two means is also displayed. Finally, the x pdfand the / cdfare plotted for each setup in Figure

218 and Figure 219.

Setup 1 -

Avionics Bay

door open

Setup 1 -

Avionics Bay

door ctased Senjp4

Setup 5 - Meas

1

Setup 5 - Meas

2

0.00 -10.00 -

I

-20.00 -30.00

-40.00 - J -50.00 n -60.00

-70.00 ^

-80.00 -

MBH

-!

J_

- ^T

-90.00 --

-100.00 -

Figure 217. Statistical analysis for TEM horn antennas for main cabin to avionics bay insertion

loss for individual setups.

165
Table 15. TEM Horn internal cabin statistics for measurements from the main cabin to the avionics

bay. The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 1 Setup 1 Avionics Bay

door open

Avionics Bay

door closed

Setup 4

Setup 5 meas 1Setup 5 meas 2

Mean (dB) -65.11 -65.47 -50.85 -63.93 - 64.72

Median (dB) - 64.48 - 64.98 -49.75 -63.66 - 64.04

Standard Deviation

(dB)

3.88 4.86 6.03 5.98 6.11

Minimum (dB) - 80.25 -85.51 -69.11 -90.38 -83.74

Maximum (dB) -58.63 -58.29 -41.41 -53.59 -54.13

Table 16. TEM horn antenna internal cabin .Y^ - distribution statistics for measurements from the main cabin to the avionics bay.

Setup 1 Avionics Bay

door open

Setup 1 Avionics Bay

door closed

Setup 4

Setup 5 meas 1

Setup 5 meas 2

Whisker-Box Plot Mean (dB)

-65.11 -65.47 -50.85 -63.93 - 64.72

X^ Mean (dB) - 62.00 - 62.00 -51.00 - 58.00 - 62.00

A(dB) -3.00 -3.00 <1.00 -6.00 -3.00

166
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Main Cabin to Avionics Bay

Setup 5 - m 1 40 -

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Main Cabin to Avionics Bay

Setup 5 - ni2

0^'

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-15

7] Pi

J -

-80 -70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

-70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

0.8

0.6

0.4

0.2

TEM

Main Cabin to Avionics Bay

Setup 5 - m 1

-90

TEM

Main Cabin to Avionics Bay

Setup 5 - m2

QO

-70 -60 -50

Penetration Bin (dB)

-40 -30 -70 -60

Penetration Bin (dB)

Figure 219. Statistical analysis for TEM horn antenna, setup 5-measurement 1 and 2, for main cabin to avionics bay insertion loss.

168
6.4.5 Cargo Bay to Avionics Bay

The DRG and TEM horn antennas were measured at various positions between the cargo bay

and the avionics bay. The VNA was placed inside the cargo bay and an RF cable was run from

the cargo bay to the avionics bay. In general, for each compartment-to-compartment

measurement we tried to position the antennas in approximately the same position for each of

these runs.

6.4.5.1 Combined TEM horn antenna positions

Three positions were measured for the TEM horn antenna type and three repeat measurements

were taken at one location. Figure 220 shows the data for the TEM horn antennas for the

maximum cabin insertion loss and a system noise floor. Typically the noise floor drops when we

place the antennas in compartments that have fewer leakage paths due to extra shielding that occurs from the outside environment. Figure 221 shows maximum insertion loss for the TEM

horn antennas around -40 dB dropping to a minimum insertion loss of -80 dB. The TEM horn

antennas were then left in one orientation and were remeasured three times to determine system

variability as shown in Figure 221 . Figure 222 shows the data for three different measurements

at different orientations in the two compartments.

Whisker-box plots are shown in Figure 223 for the following center frequencies, (1) 100 MHz,

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these

plots are from a 200 MHz bandwidth around each center frequency. The plots show that the

median insertion loss for these frequencies have values from about -58 dB to -90 dB. The

maximum value for these frequencies is approximately -50 dB in a 200 MHz bandwidth around

a center frequency of 1500 MHz, and the minimum insertion loss is -1 18 dB in a 200 MHz

bandwidth around center frequencies of 900 MHz.

The/' pdffor all DRG horn antenna measurements is shown in Figure 224 and the/' cdffor all TEM horn antenna measurements is shown in Figure 225. The histogram in Figure 224 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -57 dB. Figure 225 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function.

169
-40

-50

CD-a

-60-

-70

-80 -

-90

-100-

-110

120

Cargo Bay to Avionics Bay

- TEM - Setup A (meas 1

)

- TEM -NOISE Floor

vvAA^.,V--^Vv./'^•'>'-'"^^^

1000 2000

Frequency (MHz)

3000

Figure 220. Cargo bay to avionics bay TEM antenna data for the

maximum insertion loss and a system noise measurement.

-a

-40

-50-

-60

-70

-80

-90 -

100

Cargo Bay to Avionics Bay

- TEM - Setup A (meas 1) - TEM - Setup A (meas 2) - TEM - Setup A (meas 3)

1000 2000

Frequency (MHz)

3000

Figure 221 . Cargo bay to avionics bay TEM horn antenna data insertion

loss data at each of the three positions.

170
aa

-40 ^

-50

-60

-70

-80

-90

-100

Cargo Bay to Avionics Bay

- TEM - Setup A (meas 1

)

- TEM - Setup B - TEM - Setup C

1000 2000

Frequency (MHz)

3000

Figure 222. Cargo bay to avionics bay TEM horn antenna data insertion

loss data at one position for three independent measurements.

Group 1 - Group 2 - Group 3 - Group 4 - Group 5 - Group 6 - 100 MHz 500 MHz 1 GHz 1.5 GHz 2 GHz 2.5 GHz

0.00

-20.00

-40.00

-60.00

-80.00

100.00

120.00

140.00

liV^aj!

T T T t

Figure 223. Whisker-box plots for all cargo bay to avionics bay insertion loss measurements

of the TEM horn antennas at several frequencies.

171
CDo

V

E

3z

TEM

Cargo Bay to Avionics Bay

(all setups)

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

-20 -10

Figure 224. Chi-squared probability density function for all TEM

measurements of insertion loss in the cargo bay to the avionics bay.

0.8

0.6

T3

tL. QU

0.4

0.2 -1

TEM

Cargo Bay to Avionics Bay

(all setups) /-)-

-80 -70 -60

Penetration Bin (dB)

Figure 225. Chi-squared cumulative density function for all TEM

measurements of insertion loss in the cargo bay to the avionics bay.

172
6.4.5.2 Individual TEM horn antenna positions

Photographs for each TEM antenna measurement location from the main cabin to the cargo bay,

its associated time-domain waveform, and a schematic showing the antenna positions inside the

aircraft are shown from Figure 226 to Figure 23 1

.

173
Figure 226 shows the placement of a transmitting 1 .2 m TEM horn antenna in the cargo bay and

a receiving 36 cm horn anterma in the avionics bay for setup A, measurements 1, 2, and 3. The

1 .2 m TEM horn antenna was located in the forward section of the cargo bay close to the

avionics bay propped on a box pointed toward the rear back comer of the cargo bay with a mixed

polarization. The vertically polarized 36 cm antenna was located on an insulated cooler pointing

toward the front of the aircraft. A time-domain graph of all three measurements for position A

for the cargo bay to avionics bay is shown in Figure 227. Traces 2 and 3 were offset, in the

positive y-direction, from measurement 1 to compare differences between the repeat

measurements.

Avionics

Bay

Figure 226. Cargo bay to avionics bay TEM horn antenna setup A.

0.003

0.0025

0.002

« 0.0015 t 0.001 E< 0.0005 -

.11 -0,0005

I

-0.001 o^ -0.0015

-0.002

-0.0025

-0.003

Cargo

Bay

Cargo Bay to Avionics Bay

~ TEM - Setup A {meas I

)

- TEM - Setup A (meas 2) - TBM - Setup A {meas 3)

'

\ '

i

'

I 100 200 300 Time (ns) Figure 227. Cargo bay to avionics bay TEM horn

antenna setup A, time-domain response.

174
Figure 228 shows the placement of a transmitting 1.2 m TEM horn antenna in the cargo bay and

a receiving 36 cm TEM horn antenna in the avionics bay for setup B. The 1 .2 m anterma was

located in the forward section of the cargo bay close to the avionics bay and propped above the

floor on a cargo net pointing toward the main passenger cabin floor. The horizontally polarized

36 cm antenna was located on the floor in the avionics bay. A time-domain graph of the

measurement is shown in Figure 229.

Figure 228. Cargo bay to avionics bay TEM horn antenna setup B.

0.003

0.0025 H

0.002

1, 0.0015 - t 0.001 E< 0.0005 w

"S -0.0005 -

I

-0001 o^ -0.0015

-0 002 -

-0,0025

-0.003

Cargo

Bay

ihWWfl^^fij^^^'^J'V*''^^^^^ ^--^^.^^-«

Cargo Bay to Avionics Bay TEM - Setup B

100 200 300 Time (ns)

Figure 229. Cargo bay to avionics bay TEM

horn antenna setup B, time-domain response.

175
Figure 230 shows the placement of a transmitting 1.2 m TEM horn antenna in the cargo bay and

a receiving 36 cm TEM horn antenna in the avionics bay for setup C. The 1 .2 m TEM horn

antenna was located in the middle part of the cargo bay and pointed toward the avionics bay.

The 36 cm TEM horn antenna was placed on the floor of the avionics bay and pointed down

toward the floor. A time-domain graph of the measurement is shown in Figure 231.

Figure 230. Cargo bay to avionics bay TEM horn antenna setup C.

0.003 •

0.0025

0.002

0.0015

0.001

0.0005

-0.0005

-0.001

-0.0015

-0.002

-0.0025

-0.003

fP#fc

Cargo Bay to Avionics Bay TEM - Setup C

Avionics

Bay

Cargo

Bay

100 200 Time (ns)

300

Figure 23 1 . Cargo bay to avionics bay TEM horn

antenna setup C, time-domain response.

176
Figure 232 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 17 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 1 8 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the /statistic. The difference between the

? 1 two means is also displayed. Finally, the x pdfand the x" cdfare plotted for each setup in Figure

233 and Figure 234.

0.00

-10.00

-20.00

-30.00

-40.00

-50.00

-60.00

-70.00

-80.00

-90.00

Setup A - Setup A - Setup A - Setup B - Setup C

Meas 1 Meas 2 Meas 3 Meas 1 Meas 1

Figure 232. Statistical analysis for TEM horn antenna, setup A (measurements 1, 2, 3), setup B

and setup C for cargo bay to avionics bay insertion loss.

177
Table 1 7. TEM Horn internal cabin statistics for measurements from the cargo bay to the avionics bay. The

sample size was 32 1 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup A

meas 1

Setup A

meas 2

Setup A

meas 3 Setup B Setup C

Mean (dB) -57.73 -59.10 -58.89 -61.12 -56.59

Median (dB) -56.98 -58.53 -57.72 -61.67 -56.10

Standard Deviation

(dB)

5.99 4.56 4.66 3.50 4.63

Minimum (dB) -78.56 -79.57 -81.70 - 76.72 -81.12

Maximum (dB) -46.97 -49.85 -51.22 - 55.94 -48.84

Table 1 8. TEM horn antenna internal cabin A^-distribution statistics for measurements from the cargo bay to the avionics bay.

Setup A

meas 1

Setup A

meas 2

Setup A

meas 3 Setup B Setup C

Whisker-Box Plot Mean (dB)

-57.73 -59.10 -58.89 -61.12 -56.59

X^ Mean (dB) - 55.00 - 60.00 - 59.00 - 59.00 - 57.00

A(dB) -3.00 + 1.00 < 1.00 -2.00 <1.00

178
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TEM

Cargo Ba\ to Avionics Bay

Setup B

u ,i^«5^.

-80 -70 -bO -50 -40 -30 -20 -10

Penea-ationBin(dB)

TEM

Cargo Bay to Avionics Bay

Setup C

OA.l-<i

-70 -60 -50 -40 -30 -20 -10

F'cnetiBUonBm(dB)

TEM

Cargo Bay 10 Avionics Bay

Setup C

-90 -80 -70 -60

Penetration Bin (dB)

-70 -60

Penen-ation Bin {dB)

Figure 234. Statistical analysis for TEM horn antenna, setup B and setup C for cargo bay to avionics bay insertion loss.

180
6.4.5.3 Combined DRG horn antenna positions

Three positions were measured for the DRG antenna and three repeat measurements were taken

at one location. Figure 235 shows the data for the DRG horn antennas for the maximum cabin

insertion loss and a system noise floor. Typically the noise floor drops when the antennas were

placed in compartments that have fewer leakage paths due to extra shielding that occurs from the

outside environment. Figure 236 shows maximum insertion loss for the DRG horn antennas

around -45 dB dropping to minimum insertion loss of -65 dB. The DRG horn antennas were

then left in one orientation and were remeasured three times to determine system variability, as shown in Figure 236. Figure 237 shows the data for three different measurements at different

orientations in the two compartments.

Whisker-box plots are shown in Figure 238 for the following center frequencies, (1) 100 MHz,

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these

plots are from a 200 MHz bandwidth around each center frequency. The plots show that the

median insertion loss for these frequencies has values from about -50 dB to -55 dB. The

maximum value for these frequencies is approximately -35 dB in a 200 MHz bandwidth around

a center frequency of 1500 MHz, and the minimum insertion loss is -93 dB in a 200 MHz

bandwidth around center frequencies of 900 MHz and 1 000 MHz.

The/' pdfiox all DRG horn antenna measurements is shown in Figure 239 and the/" cdffor all TEM horn antenna measurements is shown in Figure 240. The histogram in Figure 239 consists

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The

theoretical average value is around -47 dB. Figure 240 is the data (dark-blue, solid trace) plotted

against the theoretical cumulative distribution function.

-40

-50

-60

ma

o

-J

-70

-80

-90 -

-100

-110

-120

Cargo Bay to Avionics Bay

- DRG- Setup D(meas 1) - DRG -NOISE Floor

1000 2000

Frequency (MHz)

3000

Figure 235. Cargo bay to avionics bay DRG antenna data for the maximum insertion loss and a system noise measurement.

181
-40

-50

^ -60 H CQ

-70 -

-80

-90-

Cargo Bay to Avionics Bay

- DRG - Setup D (meas 1) - DRG - Setup D (meas 2) - DRG - Setup D (meas 3)

-100

1000 2000

Frequency (MHz)

3000

Figure 236. Cargo bay to avionics bay DRG antenna data insertion

loss data at one position for three independent measurements.

-40

-50-

-o

-60 -

-70 -

-80

-90-

100

Cargo Bay to Avionics Bay

- DRG - Setup D (meas 1) - DRG - Setup E

- DRG - Setup F

1000 2000

Frequency (MHz)

3000

Figure 237. Cargo bay to avionics bay DRG antenna data insertion

loss data at each of the three positions.

182
Group 1-900 Group2-l Group

3

-1.5 Group4-2 Group 5 - 2.5 MHz GHz GHz GHz GHz

0.00

-10.00

-20.00

-30.00

-40.00

-50.00

-60.00

-70.00

-80.00

-90.00

100.00

I T

Figure 238. Whisker-box plots for all cargo bay to avionics bay insertion loss measurements of the DRG horn antennas at several frequencies.

200 -n

160

•^ 120

CD

80

40

DRG

Cargo Bay to Avionics Bay

(all setups)

mtff*^ aC

if

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

-20 -10

Figure 239. Chi-squared probability density function for all DRG

measurements of insertion loss in the cargo bay to the avionics bay.

183
0.8 -

0.6 -

oa

-aQO

0.4

0.2

DRG

Cargo Bay to Avionics Bay

(all setups)

0—

f

-60 -50

Penetration Bin (dB) 30

Figure 240. Chi-squared cumulative density function for all DRG

measurements of insertion loss in the cargo bay to the avionics bay.

6.4.5.4 Individual TEM horn antenna positions

A photograph for each TEM antenna measurement location from the main cabin to the cargo

bay, its associated time-domain waveform, and a schematic showing the antenna positions inside

the aircraft is shown from Figure 241 to Figure 246.

184
Figure 241 shows the placement of a transmitting DRG horn antenna in the cargo bay and a

receiving DRG horn antenna in the avionics bay for setup D, measurements 1, 2, and 3. One

antenna was located in the forward section of the cargo bay close to the avionics bay and

propped against a box pointed toward the rear back comer of the cargo bay with a mixed

polarization. The other vertically polarized antenna was located on an insulated cooler pointing

toward the front of the aircraft. A time-domain graph of all three measurements for position D

for the cargo bay to avionics bay is shown in Figure 242. Traces 2 and 3 were offset, in the

positive y-direction, from measurement 1 to compare differences between the repeat

measurements.

Figure 241 . Cargo bay to avionics bay DRG horn antenna setup D.

0.003

0.0025 H

0.002

0015

0.001

0.0005

-0.0005

-0.001 -

-0.0015 -

-0.002

-0.0025

-0.003

-^iIhHK'IH**^

'lf|tt^>tt> 4ftt i » »ii

Cargo Bay to Avionics Bay

- DRG - Setup D (meas 1) - DRG - Setup D (meas 2) - DRG - Setup D (meas 3)

200 300 Time (ns)

Figure 242. Cargo bay to avionics bay DRG horn

antenna setup D, time-domain response.

185
Figure 243 shows the placement of a transmitting DRG horn antenna in the cargo bay and a

receiving DRG horn antenna in the avionics bay for setup E. One antenna was located in the

forward section of the cargo bay close to the avionics bay propped above the floor on a stack of

insulation pointing toward the front comer of the cargo bay with a mixed polarization. The other

antenna was located on an insulated cooler pointing down to the floor of the avionics bay. A

time-domain graph of the measurement is shown in Figure 244.

Figure 243. Cargo bay to avionics bay DRG horn antenna setup E.

0.003

0.0025

0.002 H

u 0.0015

-o2

-=_ 0.001 E< 0.0005

-0.0005

-0.001

-0.0015

-0.002

-0.0025

-0.003

4wK*«t*.

Cargo Bay to Avionics Bay DRG - Setup E

100 200 Time (ns)

Figure 244. Cargo bay to avionics bay DRG

antenna setup E, time-domain response.

300

horn

^m

186
Figure 245 shows the placement of a transmitting DRG horn antenna in the cargo bay and a

receiving DRG horn antenna in the avionics bay for setup F, measurements 1 and 2. One

antenna was located in the middle part of the cargo bay suspended from a support point toward

the avionics bay. The other antenna was placed on the floor of the avionics bay pointing toward

the front of the aircraft in a mixed polarization. A time-domain graph of the measurement is shown in Figure 246.

Figure 245. Cargo bay to avionics bay DRG horn antenna setup F.

0.003

0.0025

0.002

oj 0.0015

-ot 0.001 < 0.0005

ra3) I -0.0005

I

-0.001 o^ -0,0015

-0.002 -

-0.0025

-0.003

IHhhi*-

Cargo Bay to Avionics Bay DRG Setup F

100 200 300 Time (ns)

Figure 246. Cargo bay to avionics bay DRG

horn antenna setup F, time-domain response.

lTfj "i-Il> Avionics

tmCEd Bay

— — — —A-^1 Cargo

I Bay

I

\

3

'' 3cED ori

"Li i J !

' i ^ ^^

187
Figure 247 shows whisker-box plots of each individual setup. The group of data was analyzed

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points.

Table 19 summarizes the statistics of each setup for the whisker-box plots, and includes the mean

value, the median value, the standard deviation, the maximum value in the group, and the

minimum value in the group. Table 20 summarizes the differences between the mean value for

the whisker-box plot analysis and the mean value for the/' statistic. The difference between the

two means is also displayed. Finally, the /' /'t//^and the/" cdfarQ plotted for each setup in Figure

248 and Figure 249.

0.00

-10.00

-20.00

-30.00

-40.00

-50.00

-60.00

-70.00

-80.00

-90.00

100.00

Setup D

Measl

Setup D

Meas2

Setup D

Meas3

Setup E

Measl

Setup F

Measl

Setup F • Meas2

Figure 247. Statistical analysis for DRG horn antenna, setup D (measurements 1, 2, 3), setup

E ( measurements 1 and 2), and setup F for cargo bay to avionics bay insertion loss.

188
Table 19. DRG Horn interna! cabin statistics for measurements from the cargo bay to the avionics bay.

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup D Setup D Setup D

Setup E

Setup F Setup F meas 1 meas 2 meas 3 meas 1 meas 1

Mean (dB) -50.75 -50.82 -50.65 -48.75 -50.70 -50.95

Median (dB) -49.59 -49.70 -49.93 -46.67 -49.99 -49.88

Standard

Deviation (dB)

5.37 6.13 6.41 8.38 4.77 5.46

Minimum (dB) - 70.22 -80.82 - 79.69 - 92.86 -65.06 -75.08

Maximum (dB) -41.22 -40.55 -40.42 - 37.24 -41.55 -41.80

Table 20. DRG horn antenna internal cabin Jc^-distribution statistics for measurements from the cargo bay to the avionics bay.

Setup D

meas 1

Setup D

meas 2

Setup D

meas 3 Setup E

Setup F meas 1

Setup F meas 1

Whisker-Box

Plot Mean (dB)

-50.75 -50.82 -50.65 -48.75 -50.70 -50.95

r- Mean (dB) -49.00 -51.00 -50.00 - 47.00 -53.00 - 49.00

A(dB) -2.00 <1.00 <1.00 -2.00 + 3.00 -1.00

189
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ac

to

n.3

o

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15

od

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190
1

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i

70

-60

-50

-40

Penetration

B &

m

. -*• " ,

--«• - 'c

, «T ^* » ' -- —^. S< s- Q22

^ - CQ i* 1

« r

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00

suiQiO jsqmnN (aP) JQD

191
7. Uncertainty Analysis

The sources of uncertainty are based on NISTIR 5019 [39], which provides a natural framework

for the identification of source uncertainties encountered in aircraft shielding measurements,

along with an efficient method for tracking and combining them.

Six sources of measurement uncertainty are considered in our analysis:

Measurement Repeatability

Range Uncertainties/Distance Correction

Time Gating

Drift

Polarization Mismatch

Signal-to-Noise Ratio

These sources of uncertainties (influence factors) were evaluated as follows:

1

.

Measurement Repeatability: For a given internal orientation, we took multiple data sets, in

which we moved the external antennas to and from the same location.

2. Range Uncertainties: We used estimates of variations when positioning the antennas for both

the reference and airframe measurements.

3. Time Gating: We determined time-gating uncertainties by varying the gate width and

performing a statistical analysis on the resulting amplitude spectra; see Appendix A for further

discussion.

4. Drift: The uncertainty due to instrumentation drift was small and was computed by use of the

data obtained from system calibration checks done before and after circumnavigating the aircraft. The uncertainty was determined by calculating the difference and dividing that by the average of

the two signals.

5. Polarization Mismatch: Polarization mismatch uncertainties occur because antennas could be

misaligned for a given polarization. We calculated one uncertainty based on a possible

misalignment of 5°. The other term comes from the possible leakage from one polarization to the other. The cross-polarization of our TEM horn antennas is approximately -20 dB, and for the

DRG antennas it is approximately -15 dB. These two factors both contribute to the polarization

mismatch uncertainty.

6. Signal-to-Noise Ratio: These uncertainties were calculated for the FAA 737-200 aircraft.

The effect of these six influence factors on the measured penetration is summarized in Table 21.

This table lists the fractional uncertainties [40, 41] resulting from each influence factor. The

signal-to-noise uncertainties were not calculated for specific signal-to-noise levels, but were

determined for measurements that have a signal-to-noise ratio of 60 dB below 9 GHz and

192
decreasing to approximately 40 dB at higher frequencies. The most significant errors are due to repeatability and time-gating uncertainties below 9 GHz, and above 9 GHz they are due to timegating and extrapolation uncertainties. Signal-to-noise is the next largest uncertainty, followed

by the range/distance correction uncertainties, polarization mismatch, and drift, respectively.

The combined standard uncertainty was computed by use of the procedure given in NIST

Technical Note 1297 [41]. The six sources of uncertainties were combined by means of the root

sum-of-squares of the linear fractional uncertainties averaged over a 400-point frequency

window. The resulting uncertainties (in decibels) for penetration are plotted in Figure 250 for

the frequency range from 800 MHz to 1 8000 MHz. The uncertainties were calculated as a

function of frequency, and therefore we have listed an approximate average value in the table

below. The rapid variation is due to the complex cavity environment where some frequencies

penetrate into the aircraft and are absorbed by the environment, while others do not penetrate.

We have broken the uncertainties into those below 9 GHz and those above 9 GHz because the

noise floor resets itself there due to the internal configuration of both attenuators and mixers.

We believe that a reasonable uncertainty bound would be at the 95 % level for the data shown in

Figure 250, remembering that this current uncertainty analysis is based on a limited set of data.

These aircraft are typically measured only once and do not lend themselves to an extensive

uncertainty analysis.

Table 2 1 . Typical penetration fractional uncertainties resulting from the six

influence factors. The signal-to-noise ratio was 65 dB.

Influence factor

Typical fractional uncertainties (dB)

<9GHz >9GHz

Signal-to-noise 0.05 0.28

Repeatability 2.83 3.51

Time gating 1.68 1.00

Range/distance correction 0.56 0.56

Extrapolation 1.12 3.43

Polarization mismatch 0.51 0.51

Drift 0.09 0.08

RSS (dB) 4.01 5.27

193
PQT3

C5

V.

a>o

c

10

8 -

6 -

4000 8000 12000

Frequency (MHz)

16000 20000

Figure 250. Combined standard uncertainty in penetration.

8. Summary and Conclusions

The data collected in this report will be used to provide guidelines for HIRF testing on various

aircraft. We have reported on the penetration measurements taken on the FAA's 737-200 at the

FAA facility in Atlantic City, New Jersey. The first part of the report discussed the initial theoretical analysis and numerical simulations prior to actual measurements. We have discussed

extrapolation measurements taken to ensure that the measurements are in the far-field of the

transmitting antenna. We have shown results for measurements taken at various azimuth angles

around the outside of the aircraft with the receiving antenna in the main passenger cabin and the

flight deck. We have looked at ground conditions and how they influence the measurements.

This report also discussed the statistics for a series of internal measurements used to study the

reverberant field characteristics within various cavities. We see that penetration typically

decreases as frequency increases. This was an important measurement effort both to aid in

understanding and to help define standard measurement procedures for HIRF testing.

The appendices are intended to provide understanding of DRG horn antenna and TEM horn

antenna boresight gain characteristics, changes in the average power as a function of the number

of positions measured, statistics for angular measurements for the Bombardier Global 5000 and

the Beechcraft Premier I A, and numerical studies of the FAA 737-200 internal measurements.

194
We thank Robert Morrison and Anthony Wilson from the FAA in Atlantic City, New Jersey and

David Walen from the FAA office in Renton, Washington for their excellent assistance and

financial support for this work. We also thank John Ladbury of the Field Parameters and EMC

Applications Project and Jolene Splett of the Statistical Engineering Division at NIST for their

valuable input into the statistics of reverberation chambers and the general application of

statistical analysis.

9. References

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environment inside an airliner. NASA Report TP-200 1 2 1 083 1 , (March 200 1 ).

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[12] N. J. Carter, Aircraft EMC, the past, the present and the future; an overview. lEE Colloq. EMC

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Meeting (May 2006).

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2008.

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August 2008.

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versus measurements. IEEE Trans. Electromag. Compat., 43(3):282-293 (August 2001).

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reverberation chamber approach. IEEE Trans. Electromag. Compat. 43(7):667-670 (August 2005).

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432 (November 1995).

[24] J. M. Stone, N. J. Carter, Statistical analysis of aircraft coupling measurements. lEE Colloq. Role of

Statistics EMC Specif Design and Clearance, 6:1-7, (May 1992).

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of electrically large, lossy cavities. Natl. Inst. Stand. Technol. Tech. Note 1361, (September 1993).

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[27] C. A. Grosvenor, D. Novotny, R. T. Johnk, S. Canales, J. Veneman, Shielding effectiveness

measurements using the direct illumination technique, 2002 IEEE Symp. Electromag. Compat. 389-394

(August, 2002).

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large sources. 2002 IEEE Trans. Electromagnetic Compatibility, 44(1): 79-86 (February 2002).

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Symp. Electromag. Compat., 2:535-539, (August 2000).

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IEEE Trans. Electromagnetic Compatibility, 2: 349-352 (August 2004).

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Reverberant Cavities. 2009 Intl. Symp. On Electromagnetic Compatibility, (August 2009).

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design principles. Natl. Inst, of Stand. Techn. Technical Note 1544. (January 2007).

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IEEE Symp. Electromag. Compat., 1-6, (August 2008).

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197
Appendix A: TEM and DRG Horn Boresight Gain Characteristics

The DRG and TEM horn antennas used in this effort were caHbrated before we deployed our system in Atlantic City. This technique can be used to derive antenna gain with a specified

resistive load (typically 50 Q) at the antenna terminals. An accurate method for doing this is the

three-antenna method. As the name implies, three transmission measurements are made with

three combinations of the three antennas. This procedure is described in detail in reference [42].

This process yields three equations that can be readily solved for either gain or antenna factor.

The gain characteristics of our DRG horn antennas are shown in Figure Al; those for our 36 cm

TEM horns are shown in Figure A2; and those for our 1 .2 m TEM horns are shown in Figure A3.

The gains displayed in these figures include the antenna input mismatch, which accounts for the

reduction of gain at the lower frequencies. The DRG horn antenna gain, plotted in Figure Al

shows that the low-frequency cutoff of these antennas occurs around 750 MHz. As the

frequency is reduced, the input mismatch increases, which accounts for a rapid decrease in

antenna gain. Mismatch and gain are not cause and effect, but a combination of both aperture

beam forming and a better input match accounts for the increasing gain at the higher frequencies.

A maximum gain of approximately 15 dB occurs at 16,000 MHz. The 36 cm antenna results,

which are plotted in Figure A2, show a maximum gain of approximately 7 dB realized at 4,000 MHz. Results for a NIST 1 .2 m horn antenna are plotted in Figure A3. This horn is longer, and it has a resistive taper, which improves the low-frequency performance. The

maximum frequency of this antenna is 1500 MHz, due to balun performance limitations, and a maximum gain of 7 dB occurs at this frequency as well.

4000 8000 12000 Frequency (MHz)

16000 20000

Figure Al . Measured boresight antenna gain for a DRG horn antenna. The gains plotted here

include the input mismatch effects, which account for the rapid decrease below 750 MHz.

198
.8 846.

'"

1 1 1 1 1 .^—Aj^-^^^r::^ ^^.^-^...-r:^^''^'"''"""""^^

- ^-"' ~

-10 -/ -

cO Gc -30

^0

-50

- 51,078. _gO

/

1 1 1 1 1 1

- 1

500 1000 1500 2000 2500 3000 3500 4000

.2 498. Honil_2^'^ Frequency (MHz)

.4x10^.

Figure A2. Measured boresight antenna gain for three identical NIST 36 cm TEM horn antennas. The

gains plotted here include the input mismatch effects, which account for the rapid decrease below 100 MHz.

Gam

Freq Frequency (MHz)

Figure A3. Measured boresight antenna gain for a NIST 1 .2 m TEM horn antenna. The gains

plotted here include the input mismatch effects, which account for the rapid decrease below 50 MHz.

199
Appendix B. Number of Positions vs. Average Power

In Section 6.3.2 we showed that to fully characterize the Bombardier Global 5000 around one

plane of the aircraft, the number of positions required is 11 97 at 1 GHz, 5973 at 5 GHz, and

21505 at 18 GHz. Since this is in practice impossible to achieve, we decided to look at the

statistics and average power as a function of position for the Bombardier Global 5000. The goal

is to provide data as a function of the number of positions and frequencies and how the average

power seen by the aircraft changes.

For this analysis we randomly chose measured positions around the aircraft, computed the

average for these measurements and then added more positions, computed the average, etc. For

the first computation, we chose 6 angular positions, which included the following angular

positions, (1) 0°, (2) 40°, (3) 90°, (4) 135°, (5) 180°, and (6) 345°. We then added 2 more

angular positions, (7) 1 20°, (8) 20° for a total of 8 positions. For a ten position average we

added the angular positions (9) 150°, and (10) 60°. We added the following angular positions for a 13 position average: (11) 330°, (12) 70°, and (13) 110°. For a 17-position average, these

additional angular positions were added: (14) 125°, (15) 160°, (16) 340°, and (17) 190°. Adding

the following five angular positions results in a 22-position average: (18) 30°, (19) 100°, (20)

140°, (21) 170°, (22) 350°. And finally for all 29 posifions, we computed the average by adding

the final 7 angular posidons: (23) 10°, (24) 50°, (25) 80°, (26) 130°, (27) 145° (28) 335°, (29)

355°. A plot showing how the penetration changes as a function of angular position is shown in

Figure B 1 . Whisker Box plots are shown in Figure B2 for various included angular positions.

This shows that as more positions are included in the average, the median, maximum, and

minimum values do not vary by more than a few decibels at the fi-equencies shown. We then

wanted to look at how the average power changes as more positions are added and this plot is shown in Figure B3 as a function of frequency and the number of included positions. We see

that at approximately 1 7 included positions the average value tends to approach some constant

value. Further research needs to be done on this analysis, because this was done on just one

aircraft.

200
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30

Figure B3. The average power as a function of frequency

and number of added positions.

Appendix C. Whisker-Box Plots for Bombardier Global 5000 and HawkerBeechcraft Premier lA

Throughout the first part of this report, we have presented whisker-box plots of the insertion loss as a function of position for various compartments in the aircraft. In this appendix, we would

like to present whisker-box plots for some of the angular scans of the measurements on the

Bombardier Global 5000 and the Hawker-Beechcraft Premier lA. These plots provided insight

into the spread of data and the maximum and minimum values at each position around the

aircraft. Also, it shows how the data change as the averaging bandwidth changes.

Figures CI, C2, and C3 show whisker-box plots for the Bombardier Global 5000 with the

receiving antenna in the main passenger cabin for results centered at 1000 MHz over a 50 MHz

bandwidth, a 100 MHz bandwidth, and a 200 MHz bandwidth. If we track one angular position

of 50° across all three bandwidths we derive the statistics shown in Table CI . We see that the

data change the most from a 50 MHz bandwidth to a 100 MHz bandwidth. The median changes

from -14.42 dB to -12.60 dB, the maximum changes from -8.42 dB to -6.57 dB, and the

minimum changes from -20.14 dB to -36.16 dB, and the spread in the data from the 25*

percentile to the 75' percentile changes from 4.10 dB to 5.23 dB. The statistics stay the same in

looking at a 100 MHz bandwidth around 1000 MHz to a 200 MHz bandwidth. Let's look at another angular position of 1 80° in Table C2. We see the data change the most from a 50 MHz

bandwidth to a 1 00 MHz bandwidth, although less at this angle. The median changes from

-26.67 dB to -25.76 dB, the maximum changes from -21.30 dB to -15.92 dB, the minimum

does not change, and the spread in the data from the 25' percentile to the 75' percentile changes

203
from 5.42 dB to 6.14 dB. The statistics stay the same for the maximum and the minimum when

changing from the 100 MHz bandwidth at 1000 MHz to the 200 MHz bandwidth. The other

changes are small compared to the first comparison. We typically use a 200 MHz frequency

averaging bandwidth to smooth the data for the DRG horn antennas and we typically use a 50 MHz frequency averaging for the TEM horn antennas.

Let's look at some data for the TEM horn antenna in Figures C4, C5, and C6. Figures C4, C5,

and C6 show whisker-box plots for the Beechcraft Premier lA with the receiving antenna in the

main passenger cabin for results centered at 1000 MHz over a 50 MHz bandwidth, a 100 MHz

bandwidth, and a 200 MHz bandwidth. If we track one angular position of 50° across all three

bandwidths we derive the statistics shown in Table 3. We see that the data change the most from

a 50 MHz bandwidth to a 100 MHz bandwidth. The median changes from -5.35 dB to -5.08 dB, the maximum changes from -2.36 dB to -1 .71 dB. and the minimum does not

change, and the spread in the data from the 25^ percentile to the 75' percentile changes from

4.09 dB to 3.07 dB. When the bandwidth changes from 100 MHz to 200 MHz, the median

changes from -5.08 dB to -5.84 dB, the maximum does not change, and the minimum changes

from -20.85 dB to -23.64 dB, and the spread in the data from the 25'^ percentile to the 75*

percentile changes from 3.94 dB to 4.07 dB. Let's look at another angular position of 180° in

Table 4. We see the data change the most from a 50 MHz bandwidth to a 100 MHz bandwidth,

although less at this angle. The median changes from -9.45 dB to -1 1 .38 dB, the maximum

changes from -5.35 dB to -5.21 dB, the minimum does not change and the spread in the data

from the 25* percentile to the 75* percentile changes from 0.40 dB to 6.14 dB. The statistics

stay the same for the maximum and the minimum when changing from the 1 00 MHz bandwidth

at 1000 MHz to the 200 MHz bandwidth. The other changes are small compared to the first comparison.

Table C 1 . Data statistics for the Bombardier Global 5000 at an angular position of 50° for three

bandwidths of 50 MHz, 100 MHz, and 200 MHz.

Bandwidth

(MHz)

Median

(dB)

25'^ percentile

(dB)

75'^ percent

(dB)

le Maximum

(dB)

Minimum

(dB)

50 -14.42 -15.83 -11.73 -8.42 -20.14

100 -12.60 -15.83 -10.60 -6.57 -36.16

200 -12.60 -15.83 -10.60 -6.57 -36.16

204
Table C2. Data statistics for the Bombardier Global 5000 at an angular position of 1 80° for three

bandwidths of 50 MHz, 100 MHz, and 200 MHz.

Bandwidth

(MHz)

Median

(dB)

25'^ percentile

(dB)

75'^ percentile

(dB)

Maximum

(dB)

Minimum

(dB)

50 -26.67 -30.14 -24.72 -21.30 -54.69

100 -25.76 -29.35 -23.21 -15.92 -54.69

200 -25.98 -30.09 -23.20 -15.92 -54.69

Table C3. Data statistics for the Beechcraft Premier lA at an angular position of 50° for three bandwidths

of 50 MHz, 100 MHz, and 200 MHz.

Bandwidth

(MHz)

Median

(dB)

25'^ percenti

(dB)

le 75' percent

(dB)

le Maximum

(dB)

Minimum

(dB)

50 -5.35 -8.03 -3.94 -2.36 -20.85

100 -5.08 -7.03 -3.96 -1.71 -20.85

200 -5.84 -8.25 -4.31 -1.71 -23.64

205
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211
Appendix D: Numerical Modeling of the 737-200

We have developed a numerical simulation study in order to help with our understanding of the

propagation of electromagnetic fields both within and coupling to the outside of aircraft. This is intended to help us and the FAA understand more fully the impact of HIRF testing and HIRF

field levels upon aircraft structures. We began with a well-characterized artifact that can be both

measured and simulated in order to compare measurement with the model. We found that the

model and the measurements agree to within some numerical error. We then adopted aircraft

simulations by first developing a rectangular model and then later developing more complex

structures that simulate a more realistic environment. Simulations in the present paper were

completed at a frequency of 1 GHz but similar analyses could be extended to other frequencies.

The only limitation at higher frequencies would be the increasing mesh size. We found that as the antenna is moved around inside the aircraft, the field behavior and propagation behavior

change significantly. We also found that the seats inside the aircraft provide a certain amount of

attenuation for the fields, and the apertures to the cargo bay help diffuse the fields inside the

main cabin. For a dipole in the aft main cabin, the field levels from the dipole to the fi^ont of the

main cabin drop from 100 V/m to 0.1 V/m. The propagation in the main cabin is also

significantly impeded as the dipole is placed in the aft cargo bay. As we model the impact of

windows, we find that leakage to the outside is not the same for every window; in other words,

energy does not leak out of the windows equally; there is definite constructive and destructive

interference that impacts the far-field radiation pattern of the aircraft. This changes as the

transmitting antenna is moved around inside the aircraft.

Although a direct comparison to measured data are not available at this time, we do see the value

of doing these types of measurements when confronting the validity of HIRF measurements and

understanding the impact of testing procedures.

This work summarizes the initial numerical modeling studies undertaken to help us understand

the interior aircraft propagation and to design test methodologies to address insight given here.

The first task involved measuring and modeling a reference box artifact designed to provide a shielding value of approximately 20 dB (see Section 3). We compared the measurements and the

model to give us confidence that the numerically modeled results are realistic. Using the model

we can look at pattern effects, radiation effects and the complex field behavior set up inside the

aircraft. The second section of this appendix shows the development of the aircraft model used

to simulate the FAA's 737-200. The model builds up the aircraft from a basic structure and

adds components such as compartments, seats, and windows until the final model is developed.

The software used to model the aircraft is a high-performance, full-wave electromagnetic field

simulator using finite-element tetrahedra. In this package we can integrate the simulation,

visualization, and solid modeling to obtain a complete picture of the simulated object. A threedimensional model is drawn, material properties, input/output ports, boundaries are defined, and

post-processing is used to look at either the S-parameters at certain ports or the fields on certain

cut planes. Automatic meshing is used to further divide the region as the convergent criteria are approached.

212
Appendix Dl. The Reference Box Artifact

The measurements taken on the reference box, discussed in Section 3.1, were compared to a simulated reference box, and the results are briefly discussed here. We used the simulations to compare simulated and measured radiation patterns to ensure correctness of modeling software.

A wire diagram of the simulated artifact with antennas is shown in Figure Dl

.

Because of the isotropic design of the box, we assume the measured radiation from the box is nearly uniform, with respect to angle. We do not assume this would hold true if holes were

drilled on only one side of the box. We measured the box in four different environments: (1) the

NIST reverberation chamber, with large modal density, (2) a large, enclosed industrial facility

having some reverberant behavior, (3) the NIST anechoic chamber with virtually no

environmental scattering [25-26], and (4) the NIST cone and ground plane facility located at NIST-Boulder, although in this case the cone was not used to generate a standard field for these

measurements [43]. We built several models using varying paddle positions and then examined

the complexity of the fields within the box and the radiation emanating from the 5 holes at the

top of the box. This is shown in Figure D2. For the measurements we used a rotatable paddle

and DRG horn antenna on the inside of the box and a DRG horn antenna on the outside of the

box. We can see from Figure D2 the field complexity within the box and the complex radiation

pattern outside the box. To simplify the model we replaced the dual-ridged horn within the box

with a small dipole. This is a reasonable substitution, because in reverberation theory the gain of

the antenna within the box is irrelevant and therefore simplifying the antenna reduces our solve

time and allows us to use less memory in the model. Figure D3 shows the complex field

behavior at the plane of the apertures, and Figure D4 shows the complex field behavior within

and outside of the box with a dipole antenna as the source.

This particular model was created to simulate the measurements made in the lab. Figure D5 is a diagram showing the measurement setup in the lab. Measurements were taken at a distance of

1 m and 3 m away from the box with the 5 open radiation apertures of the box pointed upward

(out through the page). The results of these measurements are shown in Figure D6, and the

simulated radiated pattern is shown in Figure D7. We can see that the measured and simulated

patterns are nearly identical in character. The radiation from the bottom of the box is less than

that from the top of the box, where the radiating apertures are located. The patterns are not

identical, possibly due to the apertures not being positioned exactly or other small variations in the model; however, they are similar enough that we feel the model is adequate to describe the

complex field behavior in a realistic way.

213
DRG horn antennas

Holes in box

Figure Dl . Wire diagram of simulated shielding artifact.

Figure D2. Complex field behavior inside simulated shielding artifact.

214
dipole

Figure D3. Dipole replacing dual-ridged guide antenna in shielding artifact.

Figure D4. Complex field behavior in shielding artifact with

DRG horn antenna replaced by dipole.

215
Ground Plane

Antennas

Rotator

Styrofoam

Tower

Figure D5. Measurement setup for shielding artifact.

Figure D6. Measured radiation pattern from shielding artifact.

216
ADPTotal at 200Q MHz

z i 7.9745e»O0 tm 7.17738^0 iSS^ 6.3800e*00

5.5827e*00 im.. 4.7854e«30

3.9881e»00 ^H 3.19O9e*0O 2.39^e*00

1.5383«*00

7.3901e-01

1.7269e-03

Figure D7. Simulated radiation pattern with 5 open apertures.

217
Appendix D2. Simulation of the FAA's 737-200

We started the aircraft simulation model by placing a dipole into a simple rectangular box both

with and without an aperture. The dipole is half-wavelength dipole resonant at 1 GHz, so the

physical size is 1 5 cm. We saw that modal structure inside the box without the aperture could be

affected by energy leaking in through a fairly large aperture in the side of the box when an

aperture was included. For the next stage of development, the rectangular box was scaled to a rough approximation of the actual aircraft. Figure D8 shows the scaled rectangular box with the

dipole source located toward the top of the model. Five apertures were added to simulate fields

coupling to the outside of the model.

Although the scaled rectangular box is a good canonical model, we decided to develop an

elliptical model that would be more realistic in terms of possible modal structure inside the

cavity. A wireframe rendering of this elliptical model is shown in Figure D9. The dimensions of

the model have been scaled down by a factor of 20, as shown in the figure. This model was

based on the Boeing 737-200 aircraft located at the FAA Technical Center in Atlantic City, New

Jersey. As shown in previous photos in Section 6, the aircraft seats were located in the first-class

section of the aircraft and in the aft section of the aircraft. The seats in the middle section of the

aircraft had been removed. This arrangement was the basis for our model. The seats were

assigned a dielectric constant of about 2.6 in later models, and a bulk conductivity of

IxlO' Siemens/m, which are the values for polyethylene, a low-loss foam. We chose to eliminate metal backs for the seats, based on current airline standards.

Dimensional information from drawings of a 737-600 series aircraft were used because they are similar to those for the 737-200 series. The aircraft dimensions of a 737-600 are 3 1 .25 m length,

3.54 m width and 4.14 m height. We scaled this down by a factor of 20 such that the model

dimensions are 156.25 cm x 17.7 cm x 20.7 cm. We made the thickness of the aircraft hull

0.55 cm so that the radius of the inner ellipse is 8.85 cm x 10.35 cm. The hull was assigned

properties for a perfect electrical conductor (pec) and the interior of the aircraft assigned vacuum

properties. We do this to simplify the model and create a reference baseline upon which we can

build. For the actual measurements we used our in-house developed TEM horn antennas and

commercially available DRG horn antennas; whereas, for the model, we used a center-fed dipole

antenna for the same reasons as discussed for the previous reference box model. The fuel tank

sits between the forward and aft cargo bays, and in later models will be completely enclosed by a

perfect electrical conductor.

We began with a simple model. Initially there are no coupling apertures to the outside of the

aircraft. This eliminates the need for a radiation boundary and allows us to investigate the

addition of various features inside the simulated aircraft before we complicate the model. Figure

DIO shows one of the first developed models. The floor of the aircraft between the main cabin

and cargo areas is modeled as a perfect electrical conducting sheet. In the first model, one

aperture was cut in the center of this sheet. For this and subsequent models there is nothing to separate the fields from propagating through the main cabin into the flight deck or into the cargo

bay areas at the front of the aircraft. In later models, we closed off the flight deck from the cargo

bay areas but still maintain access from the main cabin, because the actual measurements showed

that there was not a lot of shielding between the main cabin and flight deck. We set our solution

218
frequency at 1 GHz. The modal structure inside in the main cabin is similar to those in the

rectangular aircraft model, except that these modes have a longer resonant wavelength. Thus,

the shape of the cavity appears to have an effect on the field structure. The electric fields leak

through the flight deck and into the cargo bay area, but the fields couple more strongly through

the single aperture in the floor. As we add more apertures, we will see that they become a dominant source of leakage into the cargo bays. For the next stage of model development we

developed a floor structure that more closely approximates the structure found in an aircraft. The

floor of an aircraft is composed of metal grid work over which a fiberglass panel is laid, creating a series of apertures in the floor. Although the exact dimensions of these openings are not

known for our aircraft, our canonical model can provide a general understanding of the

propagation and intensity of the fields coupling through these apertures. Figure Dl 1 has the 15

apertures cut into the metal floor separating the main cabin and the cargo bay areas. This figure

shows that the field intensity is more uniform in the cargo bay areas than for coupling from a

single aperture. We also see a modal structure developing within the cargo bay. At this point

there is still just a single cargo bay area into which fields can couple either from the main cabin

through the flight deck or through the apertures in the floor. A 3 -dimensional view of the fields

is shown in Figure D12. The cuts are taken in the XZ and YZ planes of the dipole main

cabin/cargo bay area. One of the first things we notice is that even though the dipole is located

in the forward main cabin, we get a strong electric field at the back of the aircraft, due to moding.

This tells us that a source in the front of the aircraft can create high field levels at the rear of the

aircraft, and the fields can also appear at other vulnerable parts of the aircraft.

The next step in the creation of the model was to incorporate seats with the properties discussed

above. We began by locating six seating areas in the "first class" section. We did not create individual seats but merely fused the three seats together to approximate the actual seating areas. We were also able to turn off certain apertures in the floor to simulate the forward and aft cargo

bays without creating hard boundaries. Figure D13 is a wireframe model showing the six seats of polyethylene whose loss characteristics are given above. There are six apertures in the floor

in the forward part of the aircraft to simulate openings to the forward cargo bay. There are nine

apertures toward the rear of the aircraft to simulate openings to the aft cargo bay. The dipole

antenna is located in the same position as previous models, and the fields are still allowed to couple through the flight deck around to the cargo bay areas. Adding a finite number of seats to the main cabin results in energy being lost from the fields, and so less fields propagate toward

the back of the aircraft or down into the cargo bay areas. We see more localized areas of the

field within the main cabin and cargo bay areas, so we no longer have a uniform field

distribution inside the aircraft. The wireframe model geometry is shown in Figure D14 for the

additional seating, and Figure D15 shows the field distribution. The model shows that the field

distribution in the cargo bay areas now have a different modal structure due to the diminishing

field strength, and we also see that the fields in the aft part of the main cabin are diminished by at least half in the presence of additional seating. We also note that the null in the electric field has

moved toward the aft main cabin, which results in a longer wavelength and lower resonant

frequency for the compartment.

The next stage in our model development was to separate the cargo bay areas into the forward

cargo bay, the fuel tank, and the aft cargo bay, and look at the coupling into each of these

individual compartments. During this first separation, we did not isolate the fuel tank completely

219
from the main cabin but allowed the fields to penetrate the floor apertures. Figure D16 is a

rotated view of the geometry along the YZ-plane to give us an idea of where the apertures

intersect each of the cargo bay areas and how the fields behave when the fields are completely

isolated from one compartment to the other. Figure D17 is a close-up view of the separation

between the forward cargo bay and the fuel tank area, and Figure D18 shows the separation

between the fuel tank area and the aft cargo bay. These views show us that the fields are not

leaking through the walls of the individual compartments into adjacent compartments. The result

of introducing more compartments is that the fields are further disrupted, the field levels are lower, and the behavior is more complex in the main cabin and cargo bay areas. Figure D19

shows the full model with the fuel tank isolated from the rest of the aircraft.

The next phase of the simulation involved creating an aperture to the outside of the aircraft. We

began by adding just a single window that was approximately the size of the windows on a real

aircraft, which are 35.6 cm (14 in.) x 35.6 cm (14 in.). We do not see much leakage through this

small aperture and don't see much activity on the outside of the aircraft with a single aperture.

We believe that this is because the window is acting like a waveguide with a cutoff frequency

below 1 GHz, the solution frequency. We added an array of 10 windows on one side of the

aircraft but didn't see much radiation, so we moved to 30 windows on a single side of the

aircraft. This new model is shown in Figure D20. This is a close-in view of the windows

closest to the radiating dipole. The field cut was taken in the center of the XZ-plane of the

windows. We do see that the fields leak through some windows more strongly than others.

Figure D21 shows the fields closer to the aft section of the aircraft away fi-om the radiating

dipole and we see that the fields do not appear to leak out of these windows, due to the fact that

the field levels are lower. Figure D22 is the same model solved at 1 .05 GHz. The field structure

is quite a bit different even for such a small frequency difference.

The final step in the current step of modeling was to move the dipole around the interior of the

aircraft as if a cell phone were emitting in different parts of the aircraft to understand field levels. The first location for cell phone radiation was in the forward cargo bay, as if someone had left it in a piece of luggage. Figure D23 shows the field levels in the XZ-plane cut along the XZ-axis

of the dipole that is in the lower half of the aircraft. Figure D24 shows the field levels in the

main passenger cabin for a dipole in the forward cargo bay. The fields in the aft cargo bay have

made their way from the forward cargo bay, through the main cabin and have entered the aft cargo bay through the apertures in the floor. Figure D24 is a YZ-plane cut along the dipole axis

showing how the fields propagate through the main cabin into the aft cargo bay. We see the field

levels decrease as the fields propagate fi"om the forward main cabin, possibly first class, through

the seats and back into the aft of the main cabin. At this point, we have now also isolated the

forward cargo bay from the flight deck by applying a metal separation, as was done previously to separate the cargo bay from the "fuel tank" area. The next thing we did was to move the cell phone into the aft cargo bay to look at the field propagation in the same three planes as in the

previous position. Figure D26 shows the field levels along the XZ dipole plane which show

fields in the cargo bay areas. The interesting thing is that this position is not reciprocal to the cell phone being in the forward cargo bay. There are virtually no fields propagating in the forward

cargo bay when the cell phone is ringing in the aft cargo bay.

220
To obtain a somewhat three-dimensional view, we plotted the XZ/YZ planar cuts to look at the

fields in the aircraft when the dipole was located in the aft cargo bay, as shown in Figure D26.

The final location for the dipole (cell phone/source) was to move it toward the rear of the main

cabin. Finally, we assembled "3D views" of the field distribution along these two planes as shown in Figures D27 and D28. Again, there are virtually no fields that make it into the forward

cargo bay area or the flight deck. Most of the energy is dissipated in the rear of the aircraft and

the aft cargo bay areas. What was interesting, and zoomed in on in Figure D27, was the

localized field intensity where the seat locations are in the rear of the aircraft. These are

specifically pointed out in Figure D28.

Radiation

boundary

Dipole

5 "windows"

-"Aircraft"

Figure D8. Rectangular model of scaled aircraft showing

modal structure and leakage from five apertures.

221
yN=\l.l cnw

\

h=20.7cm <|-^

L=156.25cm

Figure D9. Wireframe diagram for elliptical aircraft model with dimensions.

Figure DIO. 737 elliptical model with no seats, no cargo bays, and 1 aperture cut into the floor.

222
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Figure Dl 1 . 737 elliptical model with no seats, no cargo bays, 1

5

apertures cut into metal floor between main cabin and cargo bay.

t •!« >«IV/»1 1^^ I. t-»u»»**:

5 JWO.WI!

* i5lW*4

}.4J»tB^3

: Mi»»-«i

i-ll»j5>*l li { nti»^4i W^ E. iv»1»^|

; »;«i-ti

; (-»*i*^} ;..»-."-ij

i t««W*4l

4.««fcJ»^l

1. nvk^i

i.tnt"*! Ln«^.«i

I.MtV.44

t.ll«»^41

1. >«»•<*:

>. t<«<ail] l.J*«*H«

t.iaM».4t l.tUN^l

1 rm.-w

«..';«••«• >.in»<.ai

» m«-«t

l.«.r:>.«

% «rrT-.*»

I VIM'^W

t «,T(.-»I

•- •W»-0]

• t. '»*r-*l

Figure Dl 2. 737 elliptical model with E-field planar cuts along the XZ

dipole plane and the main cabin/cargo bay YZ axis. 223
6 seats in

"first class"

apertures in

floor of aircraft

Figure D13. Wireframe model of the 737 elliptical

model showing model geometry with 6 seats and 1

5

apertures.

1 6 seats

apertures in floor

of aircraft

Figure DM. Wireframe model 737 elliptical model with 1 5 apertures to cargo bay area and 16 polyethylene seats.

224
Figure Dl 5. 737 elliptical model with 1 5 apertures in cargo bay area and 1 6 polyethylene

seats.

forward

cargo bay

"fuel tank

apertures to

cargo bays

Figure D16. Full model with 16 seats, 15 apertures, no windows, and

separate cargo compartments.

225
.1 -^j/^-VH-HI

forward

cargo bay dipole

I 1 «oo»«-0:

aperture

location

"fuel tank"

I

sects

Figure Dl 7. Close-up view showing separation between forward cargo bay and "fuel tank"

area.

tank"

aft main cabin

aft cargo bay

Figure Dl 8. Close-up view of separation between "fuel tank" area

the aft cargo bay, and the aft main cabin.

226
« PI«M[V.^k| ^^m i,*..'^*!**^ * 4^^«t-«]

» «1i»»*^l

* ;»i*-*i B^r I forward -^~^_F >dipole 1 I.

« imft^x ^Wm^i ^

i-fet.'

1.

t. >»•>•«

17«»»^ cargo bay ^^ v.ttxm'ti •.MHaM

Hi nil iW ».««Mri« V

>. ifff« \.

t.«]yr>H« \

•- lUtf^t \. "fuel tank" ' W^ ^ seats »»>iii» 8 ». !»••• /

.IKMl-W /

l.li>«»i-*l' f /

».>«»>«) /

CL iMb-*i 11 /

J. IM-f. *1 /

x-nrf.-n / aft cargo ' V

I. :*•*-«) bay j

1 d

Figure D19. Model showing the isolation of the "fuel tank" area from the fields.

C FlMldlV/n]

I..1);S<M:-Ct

4.21 Tat-MJi

J. Hl»»-<Jt

f. »4?c-CB

t.et »«•«(!

9.9:>i2t-OC S.tSJ3t-CC

I ^H ].uis«*e9 ^H SOTiOr-Ce

I ^H s.e;n>-et

I ^^1 mi7coi

{ ^^H S.«ttIW-Cll

^^^ ; tt-BOf-Cl

Figure D20. Radiation from windows located closest to dipole.

227
dipole

leakage from

windows

Figure D2 1 Fields inside and through windows at a solution frequency of 1 .05 GHz.

r FlvldLV/nl ^^^ CW«M«-<]2 ^1 * pj«t%,-e! ^m ^ H -» sap. -*) 1

3. .- -> 3t»* -CI i *- 2179«*«I

?a!Lr«*ei ?SB%«*«H

:3!fi7«-«l TTa»,^i

t!*iae>fil i*,>ar«et

» ."l«ii?'***0 >•»*«» -eo

* 9>*3ac««D

&697a*<!U W^M S2°»2a<CC I^H ie2>B-oe ^^^1 5vft»e.«! ^^H 2 Ol5 3&«.OC ^^^M Mt»«-CO ^^H 5S9S«-«ff l^^l ei-^t^-fiv ^^H fi£9C«~«l ^^^1 9;e3«-«i ^^H s esxi.^i ^^^1 £9te«-ei ^^H «517«-^l ^^^B 9«?7«-C| ^^^1 jJl«.«-<H H ' 9110«-«i

.??r>e Ol H •- ;'-tit**e-«l c««u*-oi

forward

cargo bay

Fuel tank

Aft cargo

bay

Figure D22. Planar cuts along cargo bay and windows at a solution frequency of 1 .05 GHz.

228
1 >..M|MH.] ^^ l.tBUftl

> n»M««i

k i.«|»C«l S.iJWr^S

t.ll^h-*)

J. HlWt^S

( MWM.** W?? J.IWM4I

1 »f«.^(

t tk»..«l

1 1M«>-«|

• aMi>»«t Mi^ i, *¥,tt»m4m Fuel tank

i '>ro>-«i

i l4Jte«M

( ;'>«»•••

h-«»M<9.««l

1 >»!(*•«« t-ft^-m

t^tam^^t

•.«*»••«

ikkntt-ci

«..ii»Xt>4l %.tnfr-9l

«.»n».«i Aft i.uar-«:

1 l>»nr-4ij 1 I ei^nr*i cargo

l.«IMr4i:

Figure D23. Fields in cargo bay areas, cut along the XZ dipole plane located

in the forward cargo bay in the lower half of the aircraft.

E Cl» %r:v/m^ ^^_ I *S»»«sl; ^H * ^Mrvttd^ •-•»•»» -«i ^H S^.i»Wt'•«3 I^H '»-il'>«»-Hll 8H » t»«»-«l W^ .- '»«.^1

( fl!i>.?«-«Jl 1 >»i»»,«o<.

t «*W»>«1

t Vl^*"-^)

It. aaft'i-rM

i*- *iBrw*<w

< fi^o-W

^ Liftl^xua

1% ^.1»€M'^I»

r »iiK».rfB

1. i7M^«^aa

t. «»<•*• <44

'' 4 t«^9«41

T »C-mt-«i

^ t t«-;*»-8i ^ » ni'v «i

i »*ii»«-flj

3 ?n*» «i

!. »Sie»-«4

a '»«««. 'ID 1 n I (•«•*. «i

1 KtO^-il

r^-

Figure D24. Field levels in main cabin with dipole in forward cargo bay.

The cut is taken along the XZ dipole plane.

229
I «ll»k I J. I1«:I<<1

:.ts.tinm

l.. M««i 1

1 »•

forward

cargo bay

Fuel tank

dipole

Main cabin

Figure D25. YZ plane cut along dipole axis showing fields propagating

from aft cargo bay through main cabin and into forward cargo bay.

I

t »a»-4*

dipole

Figure D26. Fields in the XZ and YZ planes with the dipole in the aft cargo bay.

230
I

« IH^^M

t»Hi

1. tuar-«i

1 !»W»-«1

dipole

Figure D27. YZ dipole plane cut with the dipole located in the aft main cabin.

I ri.MtwV] ^^ 1 «*t>-«.' ^^1 t 4:t#«t,«; ..»*... ^H » .'»)*i4i ^H >^ tl^h-«> ^H > n«;i-«: PI . —.*

i *%f»««i

t 'T**^;

1 >»••-*) i|| 1 !«*••••)

«. mut^^rn •--»»»•

• •Mt»a

«uMV»<«l LROlfti

1 laffc <i I-HnHN

r«n(<«*i

x-t»«4»H» i.OMfM

t-<1>M»« i-CMM-SI

• l"**-*! 1.U7^<«1

% lUto-*:

i.Bi.'T-n

i. t*;r«-«i

J I'l*. «i

I ii;*>-«i

I i»»».-#i

1 i<««>-«i l«Mi-*I

dipole

Figure D28. "3D" view of fields in aircraft with the dipole located in the aft main cabin.

231
^^m

r VN..u[v/»l

I dMnOv-Mtl ^^^^Hm^1

>

•- »«>..«i •^MM^l ^^^^^^^^1

^^^^^^^^^^V^ ^^1 ^^H

•. :m*««i ^^^^^^^^B^^^' ^^^^^^^ ^^^^^^H

V l|-«i~«> ^B^j^^^^ ^^^^^^H 11 ^^^^^^|: m

i

1I >ta«.^'XM-^I ^^^^^^H' ^^M ^^^^l^^l

! 1 1»»»«^4 ^ ,_ . ^^^^^H

• «•>••« ^i;r;^ l.«'M»B«<B ^^H

i » mMwia '#' ^ ^^M j ^. Ai«?>->fl» ' .i-- -1

1 J ir>i>-«i ^'% . ^^^^H

1 <*>>...» *—^^^^^^H

??»-

^^^ seats

j t,>3ii*»iW •"

1 *}t— ^^^^^H

I Dtb-idl - •

j L^ ^^^^^^H

il.t9Wa-«t

1 tJ^Av^M ,•: } i Ir ^^H

.'A >

fl »»»»»-« 'v ' \ ^^^^^^H

1, M£r^t~0i ' ! • !ai<.*i

ir ^^H

J. airt-ti ^^^^^^H Hi i

: nitftitn»>-«i ^^H

}.n£A«-«i '-,

. '''

1 vm>«i ''* 1- m 1 n^w-ri -.-"' ^^^^^^H

i.«e««'« .

>'

' ^^M

dipole — I

1 J"^^

Figure D29. Zoom-In view of Figure D27 showing increased field intensity in the seats of the aircraft.

232
Appendix E: 737-200 Measurement Equipment List

The main equipment used in the evaluation of the Bombardier Global 5000 is listed below:

Agilent N5230A PNA-L (300 kHz to 18 GHz) with a maximum of 16001

frequencies/trace.

Hewlett Packard 8753ES VNA (30 kHz to 6 GHz) with a maximum of 1601

frequencies/trace.

Insulated Wire (IW) Cables (4 m to 10 m)—we used phase-stabilized cables to avoid

phase drift with temperature variations.

Miteq Optical Fiber Link MBDRVMODT (1 1 GHz version)—this unit has the ruggedness

and temperature characteristics for field use.

Miteq Optical Fiber Link SCMR/SCMT (18 GHz version)—this unit has the ruggedness

and temperature characteristics for field use.

HP 1 1 7 1 3 A Switch Controller and HP 3 78 1 Switches

HP 59306A Relay Actuator

HP E3615A DC Power Supply for relay control

AML 0120L2403 Amplifier for DRG antennas

Harrison 6205 DC Power Supply

Two 1 .2 m TEM Horn Antennas designed and built at the NIST Boulder Laboratories

One 36 cm TEM Horn Antenna designed and built at the NIST Boulder Laboratories

Three 3115 DRG Horn Antennas

NIST-developed "RADAR" Labview program used to perform time/frequency

transformations, time gating, and signal processing

NIST-developed ""multical" Labview program used to perform multiband VNA

calibrations and to circumvent the limitation of only 16001 frequency points. This

program permits an arbitrarily large number of frequency points. In practice, we

typically use as many as 48003 points.

* Certain commercial equipment, instruments, or materials are identified in this paper in order to adequately specify

the experimental procedure. Such identification does not imply recommendation or endorsement by the National

Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily

the best available for the purpose.

233

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