SUMMARY DATA REPORT - 5 

PROPAGATION OF EM SIGNALS IN UNDERGROUND 

METALINON-METAL MINES 

MAGMA COPPER COMPANY- SAN MANUEL MINE 

PREPARED FOR: U.S. DEPARTMENT OF THE INTERIOR 

BUREAU OF MINES 

4800 FORBES AVENUE 

PITTSBURGH, PENNSYLVANIA 15213 

UNDER: CONTRACT 50308012 

PREPARED BY: TERRY S. CORY, P.E. 

2857 MOUNT VERNON RD. S.E. 

CEDAR RAPIDS, IOWA 52403 

APRIL 1981 
1.0 INTRODUCTION 

This report presents test results, data evaluations, and typical system 

performance expectations based on wireless electromagnetic propagation 

measurements performed in the MAGMA Copper Company's San Manuel mine near 

Tuscon, Arizona during March 30 through April 2 1981. 

In particular, and at the Bureau's request, this work was coordinated with 

testing of MP prototype vehicular radios being developed by A.R.F. Products, 

Inc. with USBM support under Contract H0308004 as part of a system to be 

marketed by Mine Safety Appliance Co. This testing also employed a prototype 

vehicular antenna developed by Terry S. Cory, P.E. with USBM upport under 

previous Contract P0382223. 

The work was performed under USBM contract 30308012, Propagation of EM 

Signals in Underground Metal/Nonmetal Mines. 

The authors wish to thank Mr. Hank Seany, Manager of Mines and Mr. Bob 

Zerga, Mine Superintendent who so kindly arranged for the visit. Particular 

thanks are given to Mr. A1 Metcalf who arranged the logistical details of 

our underground work, and whos forward thinking program toward improving 

general mine communications at MAGMA provided the test-bed context for 

evaluation of the prototype equipment. The authors also wish to thank Benny 

Jiminez, Paul Ayala, Lorenzo De La Cruz, and Kent Billhartz for their 

day-by-day support of the testing. Mr. Jiminez 'a effort was instrumental in 

performing the testing, and he also provided a detailed understanding of the 

existing multi-level, multi-frequency trolleyphone system at MAGMA. 

the authors are also indebted to Dr. Larry Stolarczyk of A.R.F. for numerous 

detailed consultations on MF technology, and who was present and 

participated in the majority of the testing. 

1.1 GENERAL BACKGROUND ON COPPER MINING AT MAGMA 

the San Manuel mine is the largest copper mine in the U.S., efficiently 

extracting copper and molybdenum sulfide from the low-grade San Manuel ore 

body.This ellipsoidal ore-shell body, with major workings located 2000-3000 

feet mbelow the surface, has ore shell thickness varying between 100 and 

1000 feet over a longitudinal extent of some 8000 feet, and with major 6 

minor crossectional axes of about 5000 and 2500 feet respectively. The San 

Manuel mine operation employs in excess of 1000 menlshift with gross ore 

production between 60.000 and 70,000 tons/day. The mining operation employs 

the block caving technique; actively being implemented on three levels 

(2075,2375,2675 feet for haulage, and 2015,2315,2615 product/grizzly 

levels). The ore haulage is largely via D.C. trolley trains to four 

(3A,3B,3C,3D) product shafts for skipping to the surface. An additional 

three shafts at two locations are used to convey men, materials, and 

developmental rock extractions into and out of the mine. On each haulage 

level, the trains carry ore an average of two miles one-way from the ore 

raises to the dump points. 

1.2 TOPOLOGICAL BRIEF OF THE HAULAGE LEVELS 

The 2375 level, on which all the testing was conducted, is illustrated in 
Figure 1 together with all locations on the measurement traverse. The drift 

crossection in the long haulage runs is essentially that of the timber 

ladder drift, illustrated in Figure 2; with some usage of the concrete drift 

(also shown in this figure). All haulage drift segments contain the D.C. 

trolley wire located just off the back(roof) center with the ground return 

wire bus also running with the "hot" trolley wire and separated about 10 

inches from it. The ground wire branches to the track at periodic intervals 

of several hundred feet. Track construction/condition is better than normal, 

with a well-laid bed of wooden ties in ballast. Partcicular attention is 

paid to track electrical bonding; which, on the long haulage runs, is very 

good (electrical bonding near the grizzly ore chutes load points is poorer). 

also in the typical haulage drift is the audio pager phone line (generally 

in one of the back/rib corners) and a 2400 VAC power cable. The usual 

air-linelwater-line large pipe bundle is typically found. The ribs and back 

had no metallic mesh covering; in the timbered drifts, the timbers were on 

both the ribs and the back spaced longitudinally on about 5-foot centers. 

1.3 IDENTIFICATION OF COMMUNICATIONS REQUIREMENTS 

The existing communications eminate from a dispatch locationon each level, 

and consist of both pager phone and trolleyphone service. Pager phones are 

largly MSA Pager 11's 6 lll's, and COMPTROL Loudmouth units. The 

trolleyphones are MSA 1601 units. A separate trolleyphone frequency is used 

on each production level; 115 KHz on the upper level, 145 KHz on the middle 

level, nd 190 KHz on the new lower level. There is currently a substantial 

amount of crosscoupling between levels of these signals; and the typical M 

spectrum contains a raster of harmonics and rectifiedlmixed crossproducts of 

these fundamentals and harmonics. 

Audio and radio communications on the grizzly level are currently limited to 

locations near certain ore passes, and are dilute. 

With this as a basis, several communication-related requirements exist. 

These include: 

-improving the conventional trolleyphonef mode of communications 

to provide improved performance near the extremities of each 

haulage level 

-wireless communications on the haulage level to serve batteryoperated service vehicles and small locomotives such that 

"stingers" ( with attendant vehicle stopping ) would not be 

required in order to reach the dispatcher 

-wireless communications on the grizzly levels to serve batteryoperated vehicles; also, an overlay of the existing trolleyphone 

frequencies on these levels to provide haulage coordination and 

to keep product level operations from becoming muck-bound 

-portable communications for maintenance/supervisory personnel 

tying into either the trolleyphone channel or into a separate 

"command/location" channel to facilitate efficient operation 

FIGURE 2 

DRIFT CROSSECTIONAL GEOMETRIES ENCOUNTERED DURING SWEPT-FREQUENCY 

MEASUREMMTS IN CAR-CLEANER OR1 FT 

TRANSMIT LOCATION CROSSECTION FOR ALL FREQUENCY RANCES AND 

RECEIVE LOCATION CROSSECTION FOR VHF MEASUREMENTS 

- 

RECEIVE LOCATION CROSSECTIMJ FOR ALL FREQUENCY RANGES 

EXCEPT VHF 
of these personnel, and to service special or emergency 

situations. 

These requirements illustrate the merits of providing for wireless 

commuaications as a part of any large-scale trolleyphone system. 
2.0 SUMMARY OF RESULTS 

The work consisted both of swept-frequency signal propagation studies from 

200 KHz - 1 mHz and of MF testing between a base station and a vehicle 

equipped with a radio at 145 KHz and 520 KHz on base-vehicle and 

vehicle-base linkages. These latter tests were structured to give 

quantitative data on a base-vehicle link @ 145 KHz and on a vehicle-base 

link @ 520 KHz. 

All work was performed on the 2375 haulage level of the mine. The 

swept-frequency tests were conducted on the car-cleaner tracked drift having 

essentially no conductors other than the track itself. The CW tests were 

conducted along a 13,000-f oot loop traverse beginning at and ending at the 

locomotive machine shop track, with the fixed test location in the radio 

shop adjacent to this track. 

The test results fall into the following categories: 

-assessment of the viability of all MF-UHF frequencies for use 

in the mine on a scientific basis 

-results leading toward improved definition of proximity coupling to the track in the MF/HF range on a scientific basis 

-an assessment of the current status of the MAGMA trolleyphone 

system, leading toward specific suggestions for improvement 

-feasibility demonstration of the use of the new MSA/A.R.F.1680 

trolleyphone in the wireless coupling mode, leading toward 

definition of communication possibilities achievable through 

the use of the new units 

2.1 OVERVIEW OF ReSULTS 

The drift dimensions at MAGMA are sufficiently small that a fully developed 

waveguide mode is not achievable until the frequency is 600 MEiz or higher. 

Moreover, te HF/VBF "null-zone" in this mine is wide and, for all practical 

purposes, extends from about 20 - 200 MHz. Over the VXF frequency range of 

20 - 200 MHz, the useful operating range is of the order of 100 feet. 

We now have sufficient data from all metal/non-metal mines to say that there 

is a definite optimum frequency range for close proximity coupling in 

tunnels. The effect is one of the normal monofilar wireless coupling 

excitation and excitation of the evanescent TElO waveguide mode cancelling 

in so far as the magnetic flux threading a potentail monofilar conductor is 

concerned. This is a broad-range cancellation effect and is not just the 

cancellation of two small amplitude signals. The full nulling effect is 

expected near the waveguide cut-off frequency. The monofilar coupling mode 

alone is only predominant up to a frequency of about 1 MHz. 

Based on the MF/HF car-cleaner track swept-frequency data, the l/radius 

squared efect of a single monofilar conductor with its return path image in 

the rock has been validated where the coupling is roughly proportional to 
the distance of the conductor (or conductor ensemble) from the interface. 

This model also accounts for the situation where a large diameter conductor, 

such as a water pipe or an air line, is poor for monofilar excitation; 

whereas, a thin conductor encourages this excitation. For a monofilar 

conductor with a nearby conductor as a return path, this is not true; and 

for a trolleyftrack excitation mode, he fall-off law is nearly l/r. 

Several problems were encountered with the performance of the existing MAGMA 

trolleyphone system. These include: 

-the harmonic and crossproduct spectra from the multiple 

trolleyphone signals contribute significantly to MF noise/ 

interference 

-there is too much coupling of trolleyphone signals between 

levels; in some locations, the signal from an adjacent level 

is stronger than that for the level being observed 

-there is a substantial attenuation of the base station signal 

power (hence,monofilar carrier current) over that expected in 

a typical system; this does not necessarily penalize a 

vehicle-base linkage path, but it definitely penalizes the 

base-vehicle linkage; this attenuation is of the order of 

30 - 40 dB 

Solution of these problems could improve the performance of the existing 

system configuration significantly, and could minimize the requirement for 

multiple J-box connections from a separate trolleyphone drive line (such as 

is used at MAGMA). 

Testing of the MSA1A.R.F 1680 radio together with the T.S. Cory vehicular 

antenna prototype (furnished to USBM) demonstrated the viability of the 

wireless base-vehicle and vehicle-base linkages at 145 and 520 KIIz out to a 

range in excess of 6,000 feet from the fixed transmit location. The 520 KEz 

tests showed that the propensity of the J-boxes to "short" the trolleyphone 

drive line to the track did n.ot significantly reduce the expected 

performance at this frequency. The vehicle-base linkage performed better 

than the base-vehicle linkage, as the vehicle used a 90 uV version of the 

1680 receiver that day. Using the 1 uV version, the performance would be 

expected to be the bilateral. 

Overall. the 520 KHz performance was better than that at 145 KHz. While this 

would be expected vehicle-base, the 145 base-vehicle performance should have 

been better. 

Sufficient data was gathered to determine the signal attenuation rates with 

distance at both 145 and 520 KHz. At 145 KHz, the rate was 4 dB/1,000 feet 

in the north mine(north haulage leg of the loop). At 520 KHz, the 

attenuation rate was 5 dB/1,000 feet in the south mine and 7 dBf1.000 feet 

in the north mine. At 520 KHz, the monofilar surge impedance or the trolley 

was determined to be 340 ohms in the south mine compared with 70 ohms in the 

north mine. This impedance relates to the ability of the line to carry MF 

current (a lower impoedance being better); and,hence, more available signal. 
2.2 RECOMMENDATIONS FOR IMPROVING EXISTING MAGMA TROLLEYPHONE SYSTEM 

these recommendations relate to those to upgrade the performance of the 

existing configuration besides the improved performance and new 

communications possibilities affordable through the use of the new 1680 

radios. 

Passband filters should be placed on each of the three base station 

transmitters on the three levels. This would greatly reduce the 

noiselinterferance present, thus permitting more sensitive reception and 

greaer communications rage. Ideally, all units in a coupled 

multiple-frequency system should have such filters; but, treating the base 

station plus reducing the inter-level coupling should improve the 

performance. 

The inter-level coupling should be reduced. This involves "sniffing out" the 

hard-wired coupling routes between levels which are generating the problem, 

and then placing tuned traps on the "culprit" conductors to minimize this 

coupling. 

There is a 30 - 40 dB loss in current between that expected to flow in the 

trolley line and that flowing into a low impedance load on the RP coax in 

the locomotive shop radio shack. This loss is 37.5 dB at 520 KHz and is 

expected to be roughly the same at 145 KHz. The maximum base station current 

from the directly-driven coax that flows in the trolley wire for 20-watt 

output capability is only 3 - milliamperes @ 145 KHz. This is way too low. 

This problem is indicative of a chronic problem in many trolleyphone 

systems. in these systems, the base station is constant-voltage coupled 

between the trolley wire (or DC bus) and the rail. For a high-impednace 

system, this inputs very little power (hence current) to the line. While a 

trolleyphone system can work on a purely voltage detection basis, the 

operating range is influenced by the increased noise susceptability, the 

effects of other vehicles (varying loadsd), and the requirement for a 

high-voltage non-sensitive receiver front end. The MAGMA system works this 

way too, even though the base station feeds a coax. By the time the 

coax/phone wire reaches the main J-box, both conductors are at the same 

potential, and the return path is already via the track1DC ground bus. 

This classic way of operating is an extension of a low-frequency (DC) 

concept; and, in general, provides way less than optimum performance from 

the system. 

The trolleyphone operation cab be improved by current-feeding (constant 

current transformation) the trolley line as a monofilar conductor. This will 

permit the natural impednace of the trolley system to boost the RF voltage 

at locations (if any) where this impedance becomes high. It will also 

guarentee near-optimum operation in the base-vehicle or base-portable 

wireless communication modes, if these are implemented, as the magnetic 

field strength present in the haulage drift is proportional to the level of 

monofilar current flowing. 

2.3 COMMUNICATIONS SYSTEM POSSIBILITIES 

In addition to permitting integrated wireless/direct-coupled trolleyphone 
operation on each haulage level, the inclusion of wireless radios with 

sensitive receivers will permit the coupling of RF carrier current to any 

conductors already passing between haulage and grizzly levels. This will 

permit the extension of communications to the grizzlt levels. Frequencies in 

the 500 - 1000 KHz range will be best for this, and operation may be netted 

directly with a lower frequency trolleyphone linkage using a repeater as a 

frequency translation device. A limited amount of dedicated wiring may be 

requred to extend operation over an area on the grizzly level. 

To affect quality wireless operation at the far ore-loading extemities of 

each haulage level, one or more repeaters may be necessary. This is because 

of the extensive signal division due to the large number of parallel tracked 

drifts in these loading areas. This necessity should be assessed following 

the recommended conversion of the base station coupling to a 

constant-current basis. 

In conjunction with the possible inclusion of wireless portable operation at 

MAGMA, base-portable one-way paging should be implemented on a tone basis, 

if necessary, to obtain the maximum range extension away from drifts with 

carrier current carrying conductors. In this mode, the paged party can 

proceed to to a location in close proximity to these conductors to enable a 

quality portable-base path. The use of repeaters in this type mine is 

envisioned to improve the coupling into conductors, or for use in a line 

amplifier mode to extend the range along conductors rather than as a 

stand-alone wireless-wireless operating means for area coverage. 
3.0 EXPERIMENTAL APPROACH 

The in-mine testing was all performed on the 2375 haulage level. A 

chronological summary of the testing is as follows: 

Tuesday, March 31- 

Swept-frequency tests over the MF ,HF,VHF, AND UHF bands were performed on 

the car-cleaner track. This drift contained essentially no conductors, save 

for the track. The transmit location was set up in a timbered section of the 

drift. The receive location was set up 243 feet away in a concrete drift 

section. MF and HF data were taken for all three principal polarizations of 

the loop antennas. The HMD orientations were set up in the drift center with 

the antenna 1.1 meters above the track. The transmit VMD orientation loop 

plane was positioned 1 foot(0.3 meters) above the rails. This geometry is 

illustrated in Figure 4. The receive VMD was alternatively positioned 1 

foot, 4 feet, and 8 feet above the rails. 

The normal deployment of the VHF and UHF antennas in both vertical and 

horizontal polarizations was made in the drift center. No signal was 

received at VHF, so the receive location was moved closer to the transmitter 

into a timbered drift section 111 feet from the transmitter. 

Also, on Tuesday, a 1680 radio was installed on a trolley-operated 

locomotive for long-berm qualitative testing by mine personnel in comparison 

with the 1601. This 'radio employed a 145 khz passband filter to minimize 

receiver desensitization. 

Wednesday, April 1- 

A 1680 base station radio was set up in the locomotive machine shop radio 

shack; another 1680 radio with a 1 uV front end and a 145 khz passband 

filter was set up on a battery powed locomotive together with the prototype 

vehicular antenna. The spectrum analyzer was set up in a man car pulled by 

thelocomotive to permit quantitative signal and noise measurements on the 

base-vehicle linkage. A retuned Collins portable antenna was used with the 

spectrum analyzer. Talking tests were conducted around the loop traverse via 

anel 17, as illustrated on the mine map of Figure 1. Quantitative tests were 

performed at the test locations given in Table 6. 

Thursday, April 2- 

The Collins 0.2 uV-front-end base transceiver and MSA 1680 vehicular radio 

were set up at 520 KHz similarly as for the Wednesday tests, except that the 

vehicular radio had a 90 uV front end and was used without a passband 

filter. The vehicular antenna tuning was changed with an interchangable 520 

Khz head replacing the 145 KHz head used on Wednesday. Thie time, the 

spectrum analyzer was set up in the radio shack to permit quantitative 

testing on the vehice-base linkage. The spectrum analyzer was coupled to one 

of the coaxial leads feeding the Collins base station transceiver with a 

Stoddard current probe. The fixed location of the spectrum analyzer 

permitted a more fine-grained assessment of signal levels than did its usage 

on the man car of the previous day. Talking tests were again performed 

around the panel 17 loop traverse, and quantitative tests were performed at 
the test locations given in Table 7. 

In the afternoon, a debriefing on all tests was conducted with mine 

personnel; and comments were solicited regarding the mechanical embodiment 

of the vehicular antenna. 

Due to the small drift crossectional size and the relative riblback 

,I roughness" created by the timbers, X-band microwave usage was deemed not to 

be appropriate for this type mine, and the CW tests were not performed. 
4.0 DATA REDUCTION AND ANALYSIS FACTORS 

The swept-frequency MF and HF data were reduced employing correction factors 

for the measurement system only, to facilitate the augmented data 

presentation for these ranges. The VHF and UHF data were reduced employing 

correction factors normalizing the results to a 1-watt transmitter into 

practical man-pack type antennas. This latter characterization permits the 

results to be used directly in the assessment of practical system 

performance possibilities. These correction factors are given in Table 1 and 

are to be added directly in dB to the data in dBm from the oscillographs. 

Derivation of these correction factors will be left to the final report on 

this contract. 

To permit quantitative assessment of the 2nd and 3rd days testing, CW 

correction factors were derived for the retuned Collins portable antenna at 

145 KHz and for the Stoddard current probe at 520 KHz. These correction 

factors are also given in Table 1. 

To facilitate range identification of locations along the measurement 

traverse, distances along this traverse to these locations measures both 

along north mine and south mine loop legs are given in Table 2. 
TABLE I 

FIELD STRENGTH DATA CORRECTION FACTORS 

0.20 NOTE: 

0.25 

MF d HF SWEPT 69.5 

FACTORS ARE THOSE 69.7 

FOR TEST SYSTEM 69.4 

ONLY AND ARE NOT 68.5 

NORMAL I ZED FOR 67.0 

PRACT I CAL SYSTEMS 65.1 

63.3 

60.7 

59.0 

CF FOR WRTABLE ANT @ 145 KHz TO CURRENT IS 

CF FOR CURRENT PROBE d 520 KHZ TO CURRENT IS 
TABLE 2 

DISTANCES TO LOCATIONS ALONG THE MEASUREMENT TRAVERSE 

ON THE 2375 HAULAGE LEVEL 

LOOP DISTANCES STARTING LOOP DISTANCES STARTING 

LOCAT I ON ON SOUTH HAULAGE ( FEET) ON NORTH HAULAGE ( FEET) 
5.0 DATA PRESENTATION & ANALYSIS 

The MP and HF data reduction has permittedthe validation of the coupling 

model for a monofilar conductor having its return path being in the 

conducting surface immediatedly adjacent to the conductor. The model for 

this analysis is illustrated in Figure 3. To enable comparisons, the 

monofilar track current was computed from this model for the test geometry 

of the track. Each rail of the track was considered to be a separate 

additive monofilar conductor, so defined. The computed results are shown in 

Figure 4. There is little difference in the model (except for coupling 

range) between the VMD and coplanar HMD loop orientations. The measured HMD 

and VMD data were reduced and are given in Tables 3 and 4. This data was 

expressed in the form of monofilar mode current in the track, and is given 

in Figure 5. As can be seen from the figure, the agreement for all three VMD 

ranges converging on a common track current is very good. 

in Figure 5, the computed results for the test system show a general 

increase in coupling with increase in frequency. This is what would be 

expected for monofilar mode excitation in a non-constrained(tunnel/drift) 

geometry. All metal/non-metal mines so far have exhibited the rapid fall-off 

of of current or field strength through the HF region(except for the case 

where the current is excited and retrieved probe-probe); a condition which 

is not physically realizable with simple monofilar mode coupling excitation 

alone. The cause for this effect has now been identified by the authors to 

be the interaction between the normalmonofilar mode excitation and that of 

the evanescent TElO waveguide mode. This effect is illustrated in Figure 6. 

The TElO mode uniformly distributes the horizontal H field vertically over 

the entryldrift crossection. The direction of this flux is so as to directly 

cancel the monofilar mode excitation. This is not a narrowband effect; but, 

is broad in spectrum. Essentially perfect cancellation will occur near the 

waveguide cutt-off frequency. 

Thus, the MF range has been shown to provide optimum close proximity 

coupling to conductors in constrained tunnels; a fortuitous event to add to 

te list of conductor-free and remote coupling optima already associated with 

mf propagation in coal mines. 

The reduced swept-frequency VHF data and UHF data are given respectively in 

Tables 5 &6 and in Figures 7 & 8. This data shows VHP transmission to be 

essentially non-existent with a range of only 100 feet or so; and with a UHF 

fully developed waveguide mode being limited to frequencies above about 600 

MHz for this type mine. 

The reduced CW range test data using the 1680 prototype radio and the 

prototype vehicular antenna are given in Tables 7& 8 respectively for 145 

and 520 KHz. The range attenuation effects are most graphically displayed in 

Figure 9 on a linear range basis, normalized to monofilar mode current. A 

similar graph for 520 KHz only, plotted on semi-log paper, is given in 

Figure 10. This graph is also normalized with respect to monofilar mode 

current in the trolley wire. The left-hand ordinate gives the monofilar 

mode current actually experienced in the radio shack. The right-hand 

ordinate gives the expected actual trolley monofilar mode current. These 

levels, differing by 37.5 dB, were determined by comparing noise spectra at 

520 KHz as received in the. shack and as alternatively received in the 
man-car. The expected 520 KHz trolley current agrees with the measured 145 

KHz current in the trolley wire, which verifies the conversion factor. 

The trolley monofilar mode current levels are notably less than those 

expected for a directly driven trolly wire from a base station. It is 

significant to note that a 1-watt portable with a loop antenna in close 

proximity to the wire can excite as much current as the directly driven 

trolley with 20-watt capability. This is because the base station drives the 

trolley on a constant-voltage basis; a chronic generic problem with the 

configuration of most conventional trolleyphone systems. 

From the data, it was possible to define the trolley monofilar line driving 

point and surge impedance levels. These are shown in Figure 11. Note that 

the north mine levels are significantly lower than those in the south mine. 

This is due to the two(north haulage-1 and north haulage-2) routes, and 

crossovers to the panel areas close to the transmitter which do not occur on 

the south route. 
FIGURE 3 

KINOFI LAR TRACK COWLING MODEL aoMETRY 

M)NOFI LAR I k 

CONDVCTOR 

FOR CAR-CLEANER TRACK DRIFT RECEPTION: 

FOR I-FOOT = 0.3 M SPACING 

H (DB) I (DB) - 17.0 

Y 

4-FOOT = 1.22 M SPACING 

H (OBI = I (DB) - 32.5 

Y 

8-FOOT = 2.44 M SPACING 

H (DB) = I CDBI--.43;8 Y 

FOR HM) I .I M SPACING 
FIGURE 4 

COMF'UTED MF/HF MONOFI LAR MOM TRACK COWLING CORRESPONDING 

TO CAR-CLEANER DRl FT MEASUREMNTS 

COPLANAR HMD LOOP ORIENTATION 

VM) LOOP ORIENTAT ION 

TRACK CURRENT( 2 COND. 1 

FREQ(M4Z) DB ABOVE I uAFPERE 

NOTES : SURGE IWEDANCE OF 100 OHMS / RAIL ASSUMED TO GROUND 

IMAE RETUW PATH IS IN GROUND(ROCK) 

TRACK CURRENT IS TOTAL OF Tk(O LOOP VALUES 

EQUIVALENT H FIELD IS 29.2 OB BELOW CURRENT FOR 

SHOWN EXCITAION LOCATIONS ( WHICH ARE ROUGHLY 

EOUIVALENT FOR BOTH ORIENTATIONS 1 
TABLE 3 

REWCED MAGNETIC FIELD STRENGTH AND COUPLED CURRENT DATA 

TAKEN ON A SWEPT-FREQUENCY BASIS IN THE CAR-CLEANER TRACK 

DRIFT WHICH CONTAINED NO OTHER SIGNIFICANT CaJDUCTORS @MF 

TX 6 RX ANTS COPLANAR HMD I. 1M ABOVE TRACK CENTER 

FREQUENCY(MiZ) DBM H(DB ABOVE IuA/M) I(DB ABOVE luA) 

RX ANT VM3 SPACED AS GIVEN ABOVE RAIL TOP . I-FT 4-FT 8-FT I -FT 4-FT 8-FT 

FREQ(MiZ) DBM DBM DBM H(C8) l(08) H(DB) I(DB) HCDB) ICDB) ABOVE IuA 

0.20 -53.5 - - +16.0 +33.0 - - - - OR I uA/M 
TABLE 4 

REDXED MAGNETIC FIELD STRENGTH AND COUPLED CURRENT DATA 

TAKEN ON A SWEPT-FREQUENCY BASIS IN THE CAR-CLEANER TRACK 

DRIFT WHICH CONTAINED NO OTHER SIGNIFICANT CONDUCTORS @ HF 

TX d RX ANTS COPLANAR HMD I, IM ABOVE TRACK CENTER 

FREQUENCY(FHZ) OEM H(DB ABOVE IuA/M) I(DB ABOVE luA) 

2.0 -58.0 + 4.0 +39.2 

4.4 -42.0 +10.4 +45.6 

7.9 -37.0 +l4.6 +49.8 

11.2 -56.0 - 5.3 +29.9 

14.4 -60.0 -10.0 +25.2 

18.0 - - - 

RX ANT VM) SPACED AS GIVEN ABOVE RAIL TOPS 

I-FT 4-FT 8-FT I -Fr 4-Fr 8- FT 

FREQ(FHZ) DBM DBM DBM H(DB) I (DB) H(OE) I(DB) H(W) ICDB) 

2.0 -26.0 -42.0 -62.0 +36.0 +53.0 +20.0 +52.5 0.0 +43.8 

4.4 -33.0 -46.5 -62.0 +19.4 +36.4 + 5.9 +38.4 -9.6 +34.2 

7.9 -50.0 -57.0 - + 1.6 +18.6 - 8.1 +27.1 - - 

H in DB ABOVE iuA/M 

I in OB ABOVE luA 

FIGURE 6 

GEOMETRY SHOWING THE DESTRUCTIVE CANCELLATION OF 

MRGNETlC FIELD COMPONENTS FROM A TRANSMITTING LOOP 

ANTENNA IN NORMAL K)NOFILAR MODE EXClTATllMJ AND 

30 WAVEGUIDE M3DE EXCITATION 

TE., WAVEGUIDE MOM EXCITATION OF MONOFI LAR 

MOM FROM LOOP MAGNE~IC 

$&LO DISTRIBUTION 

ILLUSTRATION OF CANCELATION OF 

MAGNETIC FIELD COWENENTS WHICH 

THREAD THE MONOFI LAR ONWCTOR 

AND ITS GROUNPRETURN IMAGE 
TABLE 5 

REDUCED VHF ELECTRIC FIELD STRENGTH DATA TAKEN ON A 

SWEPT-FREQUENCY BASIS ON A I 11 FOOT PATH IN THE CARCLEANER TRACKED DRl FT 

HORIZONTAL POLARIZATION VERTICAL POLARIZATION 

FREQ(WZ1 DBM E(DB ABOVE I uV/M) DBM E(DBAB0VE IuV/M) 

40 - - - - 
TABLE 6 

FREQ ( WZ) 

200 

300 

400 

500 

600 

700 

800 

900 

1000 

REDUCED UHF ELECTRIC FIELD STRENGTH DATA TAKEN ON A 

SWEPT-FREQUENCY BASIS ON A 243 FOOT PAM IN ME CARCLEANER TRACKED DRIFT 

DBM 

HORIZONTAL WLARIZATION 

E(DB ABOVE I uV/M) DBM 

VERTICAL POLARIZATION 

E(DB ABOVE IuV/M) 
SWEPT-FREQUENCY VHF REDUCED DATA TAKEN IN 

CAR-CLEANER TRACKED DRIFT AT A RANGE OF 

Ill FEET FROM THE TRANSMITTER 
LL 

20 

C Z 

4 2 

I- W 

SUE o!-- i3"Z 

3 LLQC - IW 

LL 3YW 

OF, z 2 $I-' 

3 K @ 

OWL 

WZ 

K4 C 

YWW 

I -IW 

I- 0 LL 

4 t.4 *, 14 0 

-ON 
TABLE 7 

REWCED DATA FROM 145 KHz TROLLEYPHONE TESTS ON THE 

BASE-VEHICLE LINKAGE ALONG ME MEASUREMENT TRAVERSE 

M3NOFI LAR CURRENT 

LOCAT I ON DBM DB ABOVE IuAWERE 

G - 5.0 +69.0 

K -25.0 +49.0 

M -20.0 +54.0 

0 -16.0 +58.0 

Q - 8.0 +66.0 
TABLE 8 

REWCED DATA FROM 520 KHZ TROLLEYPHONE TESTS ON THE 

VEHICLE-BASE LINKAGE ALONG THE MEASUREMENT TRAVERSE 

MONOFI LAR CURRENT 

DBM DB ABOVE I uAWERE 

-39.0 +22.4 

-39.0 +22.4 

-47.0 +14.4 

-54.0 + 7.4 

-57.0 + 4.4 

-53.0 + 8.4 

-59.0 + 2.4 

-69.0 - 8.1 

66.0 - 4.6 

-64.0 - 2.6 

-73.0 -1 1.6 

-67.0 - 5.6 

-54.0 + 7.4 

-35.0 +26.4 

-60.0 + 1.4 

-49.0 +12.4 

-45.0 +16.4 

-43.0 +18.4 

-38.0 WRT 

-45.0 VEHIC +23.4 

-30.0 PORT 

-28.0 VEH 1 C +31.4 

-32.0 +29.4 

-35.0 +26.4 

-30.0 PORT 

-43.0 VEHlC +18.4 

-50.0 +I 1.4 

CORRECTED FOR 

11 II 

II 11 

II II 

It I1 

It II 

11 II 

II I1 

11 It 

PREAW 

II 

I1 

II 

II 

It 

II 

11 

II 

NOTE : THESE CURRENT VALUES AS RECEIVED IN THE RADIO SHOP ARE 

INCREASED BY 37.5 DB TO GIVE ACTUAL MONOFI LAR CURRENT 

ON THE TROLLEY SYSTEM , 
FIGURE 9 

REDUCED DATA EXPRESSED AS MONOFILAR MODE 

CURRENT FROM TFEOLLEYPHONE TESTING ON BASEVEHICLE AND VEHICLE-BASE PATHS AT 145KHZ 

AND 520 KHz RESPECTIVELY 

2 3 

RANGE - KI LOFEET 
FIGURE 10 

REDUCED DATA EXPRESSED AS MONOFILAR MODE 

CURRENT LEVELS ON VEHICLE-BASE PATH AT 

520 KHZ DIFFERENTIATING BETWEEN CURRENT 

OR1 GI NAL OSC I LLOCaAPHS OF MF SWEPT-FREQUENCY 

DATA TAKEN ON CAR-CLEANE3 TRACK DRIFT 

- 

TX 8 RX ANTS VMD,RX @ I-FT, TX @ I-FT 

+ -- 

TX & RX ANTS COPLANAR Hb0 1.1 M ABOVE TRACK TX '8 RX ANTS VMD,RX @ 4-FT, TX @ I-FT 
ORIGINAL OSCll 

DATA TAKEN ON 

.LOGRAF 

CAR-CL 

FIGURE 13 

'HS OF HF SWEPT-FREQUENCY 

TX 8 RX MTS VMD,RX @ I-FT, TX @ I-FT 

- 

TX a RX ANTS COPLANAR HMD 1.1 M ABOVE TRACK TX 8 RX ANTS VtJ0,RX @ 4-FT, TX @ 1-FT 

TX 8 RX ANTS VMD,RX @ 8-FT, TX @ I-FT 
FIGURE 14 

ORIGINAL OSClLLOGRAPHS OF VHF SWEPT-FREQUENCY 

DATA TAKEN IN THE CAR-CLEANER TRACKED DRIFT 

HORIZONTAL POLAR1 ZAT ION 

- .-- 

VERTICAL POLARIZATION 
ORIGINAL OSCILLOGRAPHS OF UHF SWEPT-FREOUENCY 

DATA TAKEN IN THE CAR-CLEANER TRACKED DRIFT 

HORIZONTAL POLARIZATION 

VERTICAL POLARIZATION 
FIGURE 16(A) 

OR1 GlNAL OSC I LLOGRAPHS FROM 520 KHz TROLLEYPHONE TESTING, VEHICLE-BASE 

LOCATION A 

XMlT FROM LOCO MACHINE SHOP, 20W IN VEHlC P 

LOCAT ION C 

CI,CAFLEANER TURNOUT;E[X)G DEPARTURE 

SAME LEVEL 

~~~ ~ - ~ -~~ ~~ ~ ~ . ~ 

LOCAT ION B LOCATION C 

Fl RST TURNOUT C2,AFTER 3-COG DEP; MOBILE CANNOT HEAR 

BASE 

NOTE: RECEIVE PREAMP NOT USED AT THESE LOCATIONS 
ORIGINAL OSCILLOGRAPHS FROM 520 KHZ TROLLEYPHONE TESTING,VEHICLE-BASE 

LOCATI CN D LOCATION F 

ABOUT 500 FT ALONG SOUTH HAULAGE PAST MIDWAY BETWEEN 3-WG DEP 17 SOUTH 

3-DOG DEPARTURE 

LOCATION E LOCATION G 

ABOUT 1000 FT ALONG SOUTH HAULACE PAST GI, PANEL 17, MAIN CROSSCUT 

3-DOG DEPARTURE 

NOTE: RECEIVE PREAM' NOT USED AT THESE LOCATIONS 

-38- 
FIGURE 16(C) 

ORIGINAL OSCILLOGQAPHS FROM 520 KHz TROLLEYPHONE TEST I NG, VEH ICLE-BASE 

.LOCATION I 

PANEL 17 

LOCATION G 

G2, 17 SOUTH, NOISY 

LOCAT I ON H 

PANEL 17, VAIN CROSSCUT 

LOCAT l ON J 

PANEL 17 NORTH 

NOTE: RECEIVE PREAF,? NOT USED AT LOCATIONS G 8 H; ALL LOCATIO?IS THEREAFTER USED 

THE PREAMP W lTW 33 DB GAIN 
FIGURE 16 (0) 

OR1 GINAL OSCI LLOGRAPHS FROM 520 KHz TROLLEYPHONE TESTING, VEHI CLE-BASE 

LOCATION K LOCAT ION L 

KI, PANEL 17 WIN TOWARD 20 CROSSOVER 

LOCATION K LOCATION M 

Y2, WIN LINE 17 NORM/2 HAULAGE NORTH HAULAGE-!,CHANGED ANT LOCATICN 
FIGURE 16 (El 

OR l GlNAL OSC l LLOGRAPHS FROM 520 KHz TROLLEYPHnNF TFST ING. VFHI CI F-RASF 

LaCATl ON N LOCATI CN P 

JUST AFTER 20, SEVERAL HUNDRED FEET 100 FT PAST 30 CROSSOVER 

LOCATION 0 

OLJ DISPATCH SHACK 
OR1 GlNAL OSCl LLOGRAPHS FROV 520 KHz TROLLEYPHONE TESTING, VEHICLE-BASE 

LOCATl'ON R LCCATION S 

RI ,5-SHAFT TURNOUT,PORTABLE( 1-2 FT FROM WIRE) S I ,A I R DOORS,PORTABLE ( 1-2 FT FROM WIRE) 

LOCATION R LOCATICN S 

R2,5-SHAFT TURNOUT,VEH ICLE 52 ,A I R DOORS, VEH I CUCAR 
FIGURE 16(G) 

ORIGINAL OSCl LLOGRAPHS FROM 520 KHz TROLLEYPHONE TESTING, VEH I CLE-BASE 

LOCATION T LOCAT ION V 

BETWEEN AIR DOORS V1,ZND SET OF AIR 030RS,PORTABLEO-2 FT,WIRE) 

ILOCATION U LOCATION V 

AFTER AIR DOORS V2.2ND SET OF AIR DOORS. VEHICULAR 
OR1 GI NAL OSCI LLOGRAPtiS FROM 520 KHz TROkLEYPHONE TESTING, VEHICLE-BASE 

LCCATION W LOCAT ION W 

wI,?ORTABLE,3-CHARLIE OEPARTURE,VERT .LOOP W3,SCHARLIE DEPARTURE,VEHICULAR 

LOCATION W 

LOCATION X 

W2,3-CHARLI E DEPARTURE,PORTABLE( 1-2 FT,WI RE) 

HORIZONTAL LCOP PORTABLE,OUTS I DE LOCO SHOP, 1-2 FT FROM dl RE 
FIGURE 17(A) 

OR1 GlNAL OSCl LLOGRAPHS FROM 145 KHz TROLLEYPHONE TESTING, BASE-VEH ICLE 

LOCATiON G LOCATION K 

GI ,NOISE, 17 SOUTH, Z-MTERS FROM WIRE K1,NOISE PLUS 190 KHz, 17 SOUTH END 

LOCAT ION G LOCATION K 

G2,17 SOUTH K2,AFTER I7-NORTH SWITCH 
FIGURE 17(B) 

OR1 GI NAL OSCl LLOGRAPHS FROM 145 KHz TROLLEYPHONE TESTING, BASE-VEHICLE 

LOCATION M 

MI,NOISE, NORTH HAULACf-I 

LOCATION 0 

LOCATION 1.l LOCAT ION Q 

M2, NORTH HAULAGE- I QI,NOISE, NEAR 5-SHAFT TURNOUT 
FIGURE 17(C) 

ORIGINAL OSCILLOGRAPHS FROM 145 KHz TROLLEYPHONE TESTING, BASE-VEHICLE 

LOCAT ION 0 

02 ,NEAR 5-SHAFT TURNOUT 

LOCAT ION X 

OUTSIDE LOCO SHOP