An Investigation of Radiofrequency Radiation
Exposure Levels on Cougar Mountain
Issaquah, Washington
May 6-10, 1985
Prepared for the
Office of Science and Technology
Federal Communications Commission
through Interagency Agreement RW27931 34401 0
Electromagnetics Branch
Office of Radiation Programs
U.S. Environmental Protection Agency
P.O. Box 18416
Las Vegas, Nevada 89114
December 1985
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EXECUTIVE SUMMARY
During May 1985, the Electromagnetics Branch (formerly the Nonionizing
Radiation Branch) of the Environmental Protection Agency's (EPA) Office of
Radiation Programs (ORP) conducted a radiofrequency (RF) radiation
investigation on Cougar Mountain, Washington, in response to a request from
the Federal Communications Commission (FCC). EPA found that FM_...rad.io
broadcast antennas are the only significant sources of RF on Cougar
Mountain. The majority of EPA's measurements were made at publicly
accessible locations relatively far from FM antennas, i.e., at distances
greater than 100 meters. The measured values are relatively low when
compared to the limits developed by various standards-setting
organizations. These limits fall into the range 100 to 1,000 microwatts per
square centimeter (yW/cm2) for FM radio frequencies.
Two types of results are presented, spatially averaged values and
maximum localized values. The spatially averaged values are most
representative of an individual's typical whole-body exposure. The maximum
values are normally associated with areas of limited extent wherein only
partial-body exposures might occur. The greatest spatially averaged power
density measured in a publicly accessible location is 700 yW/cm2 within
25 feet of a tower which supports an FM antenna. Near residences, the
greatest spatially averaged power density found was 117 yW/cm2. Measured
localized maximum power densities in two publicly accessible areas exceeded
the 1,000 yW/cm2 ANSI radiation protection guide adopted by the FCC.
These include areas near the unfenced KMGI/KZOK/KMPS tower, where one
measurement exceeded 2,000 yW/cm2, and locations near one residence where
a maximum of 2,350 yW/cm2 was found. Indoors, highly localized power
densities reached 350 yW/cm2, while spatially averaged values did not
exceed 23 yW/cm2.
Because power density values are likely to increase with height above
ground on Cougar Mountain, and because the conducting objects normally found
in structures tend to enhance ambient RF fields, the siting of new
multistory dwellings near the high power antennas on Cougar Mountain should
be approached with care. Also, cooperation among broadcasters will be
needed to prevent tower climbers in the Ratelco North Lot from exposure to
power densities exceeding the ANSI radiation protection guide.
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TABLE OF CONTENTS
Executive Summary i
Table of Contents i i
List of Tables and Figures iii
Background ,.. 1
Equipment 1
Procedures .. 3
Results and Discussion ".. 6
Summary 10
Tables 13
Fi gures 20
References 36
Glossary 37
Appendix - Equipment and Calibration Information 38
n
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LIST OF TABLES
1. Transmission Frequencies on Cougar Mountain by Tower Number 13
2. Narrowband Measurements and Broadband Comparisons 17
3. Indoor Measurement Data 18
LIST OF FIGURES
1. Map of Seattle Area Showing Location of Cougar Mountain 20
2. Computer Plot of Calculated Power Density Values
for Cougar Mountain 21
3. Cougar Mountain Spatially Averaged Power Density Values
and FOISD/Holaday Comparisons Attachment
4. Site 2 FM Spectrum 22
5. Site 3 FM Spectrum 23
6. Site 4 FM Spectrum 24
7. Site 5 FM Spectrum 25
8. Site 6 FM Spectrum 26
9. Site 7 FM Spectrum 27
10. Site 8 FM Spectrum 28
11. Site 9 FM Spectrum 29
12. Site 7 Wideband Spectrum 30
13. Probability Plot for Cougar Mountain Spatially Averaged
Power Density Values in Accessible Areas 31
14. RATELCO North Lot Maximum Values 32
15. Probability Plot of Power Density Values at All Measured
Points Inside RATELCO North Lot 33
16. RATELCO KUBE Enclosure Maximum Values 34
17. Maximum Values Near KMGI/KZOK/KMPS Tower 35
Al. Holaday Model 3001 Electric field Calibration in
FM Frequency Band 39
A2. Narda Model 8616 (8631 Probe) Magnetic Field Calibration
in FM Frequency Band 40
A3. NanoFast Model EFS-2 Fiber Optic Isolated Spherical Dipole
Antenna Factor 41
A4. Antenna Factor Graph for the Tunable Dipole with 20 Feet
of RG-55 Cable '.. 42
A5. AEL Model APX 1293 Crossed Log Periodic Antenna Factor
for 1 to 13 GHz 43
A6. Watkins Johnson Model WJ 8549 Antenna Factor for 1-18 GHz 44
m
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AN INVESTIGATION OF RADIOFREQUENCY RADIATION
EXPOSURE LEVELS ON COUGAR MOUNTAIN
ISSAQUAH, WASHINGTON
MAY 6-10, 1985
Background
Cougar Mountain lies approximately 12 miles east-southeast of Seattle
with its summit 1400 to 1500 feet above Seattle (Figure 1). The mountain's
elevation above Seattle has made it a popular location for broadcasters to
place their antennas. Twenty-two towers sit atop the mountain today,
supporting 10 FM antennas, several microwave point-to-point dishes, and a
myriad of o.ther low-power communications antennas (Table 1). Twenty years
ago, when few residents and fewer antennas resided on Cougar Mountain, there
was little concern about the levels of electromagnetic radiation there. As
more people moved to the mountain for its magnificent views, as more
broadcast and communications companies chose Cougar Mountain for its
advantageous position over the Seattle area, and as questions arose in the
popular and scientific press about the biological effects of radiofrequency
(RF) radiation, many residents developed a concern about the possible
hazards of being so close to an "antenna farm". They wrote to their county
government, to the Federal Communications Commission (FCC), to the
Environmental Protection Agency (EPA), and to their Congressional
representatives seeking information on the levels of RF radiation on the
mountaintop, inquiring about the possibility of any associated health
consequences, and requesting relief from the addition of more antennas to
the area.
The FCC responded to citizens' concerns by requesting an EPA study of
the RF levels on Cougar Mountain. The Electromagnetics Branch (formerly the
Nonionizing Radiation Branch) within the EPA Office of Radiation Programs,
assisted by personnel from the FCC Seattle and Washington, DC offices,
conducted the study during the week of May 6, 1985. This report describes
that study and is provided by EPA to the FCC under the terms of Interagency
Agreement number RW27931344-01-0.
Equipment
The strength of RF fields is commonly measured using broadband
isotropic electric or magnetic field meters, or antennas connected to
tunable field strength meters. Broadband equipment is used to provide an
indication of the total RF field at a point while narrowband equipment
provides detailed information on the RF intensity at any particular
frequency. This study employed both types of equipment.
The Fiber Optic Isolated Spherical Dipole (FOISD) was used for
narrowband or frequency specific measurement of frequencies up to 700 MHz.
The FOISD's small size (a sphere about 10 cm in diameter) allowed us to
calibrate it in a small calibration apparatus in our facility at frequencies
of major interest before leaving for Seattle. The FOISD's size and the fact
that it does .not need to be adjusted to-each frequency individually also
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make it far more convenient to use in the field than the larger and more
cumbersome half-wave tuned dipoles, which require readjustment at each
frequency of interest. The FOISD was calibrated in a transverse
electromagnetic (TEM) cell in the Electromagnetics Branch laboratory in the
Las Vegas Facility. The report, An Automated TEM Cell Calibration System
(1), describes this calibration facility.
Between 700 and 1000 MHz, a Singer Model DM-105A-T3 half-wave., .tuned
dipole was used. We have experimentally determined the antenna factor for
this narrowband Singer system.
Above 1000 MHz we used an AEL Model APX-1293 crossed log periodic
antenna (1-13 GHz), and a Watkins Johnson Model WJ 8549 vehicle-mounted
omnidirectional bicone antenna (1-18 GHz). We determined the calibration
factor for the AEL and Watkins Johnson antennas based upon
manufacturer-supplied data for the frequency range that would be of primary
interest to us as we used that antenna. For example, our antenna factor
curve for the Watkins Johnson omnidirectional bicone antenna (see Appendix)
is based upon a 2dBi gain figure supplied by Watkins Johnson for a frequency
of approximately 15 GHz, a frequency which is within the range (2-18 GHz)
for which we used that antenna.
All these antennas were linked to a Hewlett Packard 8566A spectrum
analyzer to measure RF electric field strengths. The analyzer was
interfaced to a Hewlett Packard 9845B desktop computer which controlled the
analyzer, processed, and stored the frequency-specific electric field data.
We used the internal calibrator in the spectrum analyzer to verify the
calibration of the analyzer itself in the field. We verified the accuracy
of the internal calibrator signal with a power meter upon our return to
Las Vegas. All calibrations referenced in this report are traceable to the
National Bureau of Standards.
Upon arrival at Cougar Mountain, we checked the response of the Holaday
3001 broadband electric field strength meter and the Narda 8616 (8631 probe)
broadband magnetic field strength instrument. It was apparent that the
Narda would be of limited usefulness on Cougar Mountain because of a serious
zero-drift on its lowest (most sensitive, i.e., 0 to 200yW/cm2) scale -
the scale where most of the Cougar Mountain values would be read. However,
the Narda's next scale (0 to 2000 uW/cm2) didป not exhibit a significant
zeroing problem and was used in a few of the higher exposure sites.
The Holaday meter does not suffer from a zero drift problem because it
self-zero's many times each second. However, the Holaday fulfilled its
manufacturer's predictions that it would overrespond in the presence of
multiple FM fields of similar intensity. Despite these problems, we decided
to use the Holaday because its stability (i.e. lack of zero drift) allowed
us to compare it to more accurate, narrowband FOISD values at several sites
and power densities. For further information on calibrations and the
equipment used in this study, see the Appendix.
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Procedures
Two months before the study, the Puget Power Company sent us a notebook
of maps, photos, contacts, and very detailed information concerning the
engineering characteristics of antennas on Cougar Mountain. Puget Power,
which owns two towers on Cougar Mountain, had gathered information on the RF
environment there in response to inquiries from the residents. The
information contained in the Puget Power book saved us days of long-distance
telephone investigation. After verifying items of interest and adding
details that we learned from the FCC, FM station engineers, and the owners
of the towers, EPA predicted the maximum RF levels that all the antennas
were likely to create on the mountaintop. (The modeling techniques we used
are described in reference 2.) These calculated power density values shown
in Figure 2, helped determine the scope of the investigation, and suggested
areas where detailed mapping of fields would be warranted. The contours on
Figure 2 are located at the greatest distance from the towers at which power
density values as high as the stated values were predicted to exist.
According to the model, much of the mountaintop would be above 100 pW/cm2
with a few locations on Cougar Mountain exceeding 1000 uW/cm2. It should
be noted that due to particular antenna characteristics, the field strength
does not decrease monotonically with distance from the antenna. Therefore,
there can be multiple contours for a single power density value. Figure 2
displays only the most conservative (i.e., furthest from the antenna)
contours for the three exposure values.
Using the modeling results, we considered how we should investigate the
mountaintop in order to present the most complete picture of the RF
environment there. We decided to collect spatially averaged values (typical
measurements which exist over a vertical planar area of about 70 square
feet) and maximum values (maximum measurement values normally associated
with areas of limited extent wherein only partial body exposures might
occur) both outdoors and indoors. While frequency specific measurements,
using the dipole antennas and the spectrum analyzer, provide the most
detailed and most accurate information, the size of the Cougar mountain area
and time constraints dictated that broadband meters be used to collect the
majority of the data.
In general we tried to obtain spatially averaged or typical values
wherever people might be located - inside and outside homes, along roads,
and even around fenced areas. Because there were so many locations at which
to measure such spatially averaged values, over 400, we used a broadband
instrument that could be handcarried and that allowed us to collect data
rapidly.
We searched for maximum values in order to characterize some areas more
thoroughly. Areas that we believe warranted this extra attention included
residences and locations close to FM antennas. We used the same broadband
meters to find maximum power density locations that we had used for the
collection of spatially averaged values because those meters are
lightweight, and can be quickly and easily maneuvered to search for peak
values.
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We used narrowband equipment at several sites to determine the
contribution of each FM station to the total power density at a given point
and to estimate the error associated with the less accurate broadband
measurements. We chose sites for narrowband measurements which were:
(a) near homes, since narrowband readings permit more accurate exposure
assessments and allow the development of correction factors for the more
numerous broadband data; and which were (b) at various distances from
clusters of FM antennas. We chose several distances from the FM_towers
because we wanted to learn the actual exposure values at those points in
order that we could assess the broadband instrument errors under different
combinations of FM signal strengths. The Hol'aday manual predicts
over-responses in the presence of multiple signals which are strong and
approximately equal in magnitude.
Frequency Specific Electric Field Data
Frequency specific data enhance the usefulness of any study not only by
providing accurate standard values against which broadband data can be
evaluated, but also by identifying the contribution of emissions at various
frequencies to the total power density at a point in space. The approach
for these measurements was (a) to seek sites at various distances from the
different frequency band antennas on the mountain, (b) to sample at a group
of sites where a wide range of field intensities existed, and (c) to measure
the fields near residences. Eight sites were chosen. All but one are
accessible to the public. A quick survey with the Holaday would locate a
point in space where the field was strong for that particular site. The
FOISD was then placed at that point in space, and collection of
frequency-specific data commenced.
The computer processed electric field data from three orthogonally
aligned FOISD measurements at each site, and saved the resulting spectra.
After each set of three FOISD measurements, the FOISD was removed from its
gimbals. We then centered the Holaday probe in the gimbals and measured the
field through a 360" rotation of the probe about the axis of its handle. An
average field intensity from that rotation was recorded for comparison with
the FOISD value for the FM band. Every value was corrected for the
frequency response of the instrument and converted to plane wave equivalent
power density units. The power density comparisons are listed in Table 2
for the eight sites. Figure 3 (the attached large fold-out map) displays
the locations of the comparison sites and identifies each with its site
number inside a triangle. (Note that in Table 2 and Figure 3 there is no
comparison site No. 1.) The other values on Figure 3 are the power density
values which are discussed in the next section of this report.
Magnetic field data were collected to determine if electric field
values could be used to reliably predict equivalent plane wave power
densities. We used the Narda 8631 broadband magnetic field probe for these
measurements. At three sites where the RF fields were great enough, we
measured the maximum magnetic field in the vicinity of the site where the
electric field values were taken, but we were unable to obtain reliable
values at 5 other comparison sites due to the zero drift problem.
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After collecting the FM band data with the FOISD, we returned to three
of the comparison points to collect information on the electric fields at
non-FM frequencies. We collected data at one site (No. 10), which was not
an FM comparison point, because it was near residences and it overlooked all
the antennas on the mountaintop. Table 2 lists these data by site number
and by the instrument used to make each measurement. Some non-FM
frequencies were sampled by taking three orthogonal FOISD measurements.
When half-wave tuned dipoles were used, we oriented them in the azimuth. ..such
that the field produced the greatest amplitude signal on the spectrum
analyzer, and then collected data from horizontal and vertical
orientations. To collect data with the crossed log periodic antenna, we
directed it at a tower which supported antennas of interest and which was
visible from the measurement point. To redirect the antenna toward towers
which were not visible from the measurement point, we took angles from our
maps and rotated the antenna accordingly. At higher frequencies we
sometimes sampled only a single polarization. In some cases we were forced
to collect peak values rather than average, because of the duty cycles and
low powers of the transmitters. The omnidirectional antenna samples in the
horizontal plane, hence it requires no azimuthal orientation. It is mounted
in a fixed vertical position on our vehicle and thus collects data from only
vertically polarized fields. Unlike the FM band data which were collected
at a height of 7 feet or less because we could not reach higher with the
broadband probe or place the FOISD higher on its tripod, the non-FM band
data were collected at heights which ranged between 5 and 10 feet because
the non-FM band antennas were placed atop our truck.
Broadband Spatially Averaged Values
Our intention was to find spatially averaged values in areas accessible
to the public (i.e. in areas that were not fenced). Although we had
considered taking data at intersecting gridpoints on the mountain, the dense
vegetation over much of the area did not allow us to establish gridlines,
much less physically move to intersection points. So we collected data
every 20 to 25 feet along each road in the area, around the exterior of
fenced areas, and near homes. (One exception to this plan was that values
were taken just inside the Ratelco North lot fence in a defoliated area in
order to speed data collection.) The areal extent of the Cougar Mountain
survey was determined by our ability to obtain on-scale indication of the
ambient field strengths on the most sensitive range of the* Holaday meter
(the equivalent of 1-2 uW/cm2). At each measurement point, we surveyed
over the point in a vertical plane about 7 feet high by 10 feet wide with
the Holaday probe. We deliberately avoided locations where the field might
be affected by nearby conducting objects (see "Maximum Values" below). We
recorded our best estimate of the spatially averaged square of the electric
field value (V'/m2) throughout the plane that was surveyed. Through
repeated measurements at the, same location, but at different times, we
became confident that our estimated spatial averages were within
approximately 30 percent of the actual spatially averaged value.
Maximum Values
Despite the fact that they may be- quite localized, maximum power
density values are important for hazard assessment and compliance
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monitoring. Maximum values are of two varieties. The first results from
unperturbed fields in space which happen to sum to a high value. These
would be at points of standing waves. The second variety is caused by
perturbation of an electromagnetic field by a conducting object. This can
dramatically enhance the field intensity over a small area. We set out to
locate the maxima by searching near the strongest sources of RF energy (the
FM antennas) and by searching for field perturbing situations in areas that
are likely to be frequented by people. In some cases those two criteria-led
us to the same area.
Near most of the FM antenna's we recorded maximum values as we moved
along the four compass radials (referenced to true North) from the base of
the tower. At ten-foot intervals from the base of the tower, we searched
for the maximum field value within our reach using the Holaday broadband
instrument. The elevated levels inside the North Ratelco lot called for a
more exhaustive series of measurements, while the relatively low levels and
dense vegetation near the KQKT tower argued against radial measurements
there. After completing the radials, we searched in areas where the radial
data suggested high field strengths would be found, and recorded those
values.
The approach for areas that would be frequented by people was to survey
the area generally but emphasize locations near conducting objects such as
fences, swing sets, etc. We did not search for maximum values that might
have occurred near transient structures like automobiles.
Indoor Measurements
The purpose of this study was to estimate the potential for human
exposure to RF fields on Cougar Mountain. Measurements inside residences
were therefore included. Three homes near the Ratelco North lot were
surveyed, room by room. In each house, spatially averaged as well as maximum
values were recorded. The residents were helpful, not only by allowing us
access, but also by directing us to locations at which previous surveys had
found elevated field intensities. Interior electric field data were
collected with the Holaday.
Results and Discussion
The data collected in this study are primarily electric field strength
values supplemented with a few magnetic field strength measurements. The
data that we report, however, are in power density units of microwatts per
square centimeter (uW/cm2). We converted the electric field strength
values to power density values, assuming equivalent plane wave conditions.
All the values reported here are corrected for the frequency response of the
instrument.
Frequency Specific Values
Table 2 displays the frequency specific measurements for 9 sites on
Cougar Mountain. The corresponding FM band spectra and individual station
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power density contributions are shown in Figures 4 thru 11. The data show
that power densities from FM band sources far exceed those from non-FM band
sources. Figure 12, a spectrum taken near site 7, highlights this
distinction between FM (88 to 108 MHz) and other frequency bands. The
spectrum plot in Figure 12, in conjunction with the data for Site 7 in
Table 2, show that the contribution to power density from frequencies
outside the FM band constitutes only one to two hundredths of a microwatt,
or less than one percent of the FM power density at this site. Hea.c.e. the
non-FM band sources contribute such low power densities that they may be
neglected for practical purposes.
A more subtle distinction than that between FM and other frequencies is
that between the FOISD and Holaday values at the 8 comparison points
(Table 2). The ratios of the FOISD to the Holaday values range from 0.53 to
1.14 for the sites we sampled. Using the FOISD as our standard for
measuring field strength, these data imply that the Holaday typically read
high and its values should be multiplied by some factor to correct for its
multiple-frequency response. Unfortunately, the only way to know what
factor is appropriate for a particular point is to take frequency specific
data at that point. Of course, if frequency specific data were available
for every point, there would be no need for Holaday readings. The dilemma:
very accurate data that require an inordinate collection time or less
accurate data which can be collected in a reasonable period of time and
whose error range can be estimated. We opted for the latter.
Each of the Holaday values presented in this report, while corrected
for the frequency response of the meter, should nevertheless be considered
to represent a range of values whose boundaries are about 0.53 and 1.14
times the stated value. This correction is necessary to account for the
Holaday's erroneous response in the presence of multiple, strong, and
approximately equal strength signals. Realizing that the Holaday's error,
and hence the appropriate correction factor, can change over short distances
as the contributions from various antennas change, we nevertheless feel
comfortable using a particular correction factor over a limited area (radius
of 50' to 100') centered on the actual comparison site. We arrived at this
conclusion after comparing the FOISD/Holiday ratios at sites 8 and 9. The
comparison values are similar at these two nearby sites.
The Narda magnetic field meter operated well at three of the sites
where the Holaday and FOISD were used (see Table 2). At these sites, the
equivalent plane wave power density that corresponds to the measured
magnetic field (corrected for the meter's frequency response) is
approximately equal to that predicted by the electric field value obtained
with the FOISD. The ratios of the FOISD to Narda values at the three sites
are 0.97, 1.20, and 1.09. These data indicated to us that electric field
values could be used to reliably predict power densities on Cougar Mountain
in the absence of measured magnetic field values.
Broadband, Spatially Averaged Values
Figure 3 shows the spatially averaged power densities on Cougar
Mountain as well as the correction factors- for the Holaday which were found
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at various points. As expected, the spatially averaged values decrease
rapidly as distance increases from FM antennas. Interestingly, the values
are far lower than those predicted by our modeling. We attribute this
discrepancy to three causes. First, the model is designed to avoid
underpredicting, so some overprediction is likely. Second, the model is
designed for level terrain. As one moves away from the towers on Cougar
Mountain, the distance from the antenna is greater and the elevation angle
from the point to the antenna is steeper than what would be predictedJf. the
area were level. Hence the actual power densities are lower than
predicted. Finally, the dense vegetation atop Cougar Mountain attenuates
the RF fields. The trees also help to increase the inhomogeneity of the
field. For these reasons, the ratio of the actual power densities to the
calculated power densities can be anywhere from about one-twentieth to one.
Figure 13 shows a probability plot of the over-400 spatially averaged
values which were measured on Cougar Mountain where the equivalent power
density exceeded 1-2 yW/cm2, the practical lower limit of detection for
the Holaday instrument. The highest of these values exceeded 700 yW/cm2.
Although there are many points that exceed 200 yW/cm2, about 95 percent of
the values are less than 200 yW/cm2, 88 percent are less than
100 yW/cm2, and 75 percent are less than 50 yW/cm2. Although the method
of data presentation used is sensitive to the selection of measurement
locations, Figure 13 provides a convenient means for summarizing the
spatially averaged data. In off-road areas, we checked the fields in the
pasture to the east of the Ratelco North lot and in the park at the old Nike
site. In the pasture, the values were remarkably uniform at about 45-50
yW/cm2. At the park, common values were about 2 yW/cm2, with the
highest levels routinely reaching no more than 5 yW/cm2. In, the most
uniform field we found, the variability over the vertical plane surveyed was
a factor of 4 from the greatest to the lowest value. It was not unusual to
see a factor of 2 in horizontal variability and a factor of 8 to 10
vertically.
To place these data in perspective, it is helpful to know that the
least stringent standard in existence for FM frequencies is 1000 yW/cm2,
published by the American National Standards Institute (ANSI) and recently
adopted by the State of New Jersey and triggering environmental reviews by
the FCC. The National Council on Radiation and Measurements (NCRP) has
prepared a draft standard at the 200 yW/cm^ level (3). The International
Radiation Protection Association (IRPA), the State of Massachusetts, and
Multnomah County Oregon have all adopted the same limiting value for
exposures in the FM band (200 yW/cm2). The City of Portland, Oregon, has
chosen a 100 yW/cm2 limit for FM frequencies within its borders. EPA
estimates that the average power density in urban areas of the United States
is about 0.005 yW/cm2, with fewer than 1 percent of the urban population
exposed to levels greater than 1 yW/cm2 (4). Figure 13 portrays the
Cougar Mountain spatially averaged values, several standards, and EPA data
on urban RF power densities. It also shows that while none of the spatially
averaged values at measured locations in accessible areas on Cougar Mountain
exceeds 1000 yW/cm2, about 5 percent exceed 200 yW/cm2 and about
11 percent exceed 100 yW/cm2. However, one of the spatially averaged
values found just inside the fence at the Ratelco North lot does exceed
1000 yW/cm2-
8
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Maximum Values
Figure 14 locates maximum values that we found along several radials in
the fenced Ratelco North lot. Several of the values inside the North lot
exceed 1000 yW/cm2, with a few surpassing even 2000 yW/cm2. In order to
obtain a general impression of the RF environment inside the Ratelco North
lot, we combined the maximum values (Figure 14) with the spatially averaged
values (Figure 3) and plotted the resulting collection of data on -a
probability scale. Figure 15 is the result, and shows that in the mixture
of maximum and spatially averaged values, a few percent of the points exceed
2000 yW/cm2 about 20 percent exceed 1000 yW/cm2, and 98 percent exceed
100 yW/cm?- After correction of these values for the Holaday's
multiple-frequency response, the ANSI limit will be exceeded inside the
Ratelco North lot.
The levels inside the KUBE fenced enclosure (Figure 16) are far lower
than those inside Ratelco North, with maximum values of about 375 yW/cm2
along the radials.
Moving to unfenced areas, just outside the Ratelco North lot west gate,
(Figure 14) are two locations where the Holaday reading approximated
1000 yW/cm2. The maximum value in the area between the KUBE enclosure and
the North Ratelco lot (Figure 16) was about 470 yW/cm2. Near the unfenced
KMGI/KZOK/KMPS tower (Figure 17), power densities at several locations
approach or exceed 1000 yW/cm2, with one nearly 1700 yW/cm2 and one
exceeding 2000 yW/cm2. It is apparent from the data in Figures 14, 16,
and 17, that the power densities decrease rapidly with increasing distance
from the tower.
The search for maximum outdoor values near residences was concentrated
just east of the Ratelco North site in a backyard play area behind the
Percival residence, the nearest residence to any of the broadcast towers.
On Figure 14 this play area is located about 100 feet east of the eastern
fence of the Ratelco North Lot, and due east of towers 4 and 5. While the
spatially averaged power density in this area was about 117 yW/cm2, the
greatest unperturbed field value we found corresponded to a power density of
about 350 yW/cm2. In perturbed fields, the values were much higher. Near
a fence, the power density rose to 1174 yW/cm2. At the end of the swing
set the maximum value was about 1450 yW/cm2, and near the chinning bar the
equivalent power density exceeded 2350 yW/cm2. Despite the fact that
these perturbed field values are very localized, they are real and can
result in relatively high partial body exposures.
Indoor Measurements
Spatially averaged equivalent power density values for the interior of
three homes near the Ratelco North site ranged from negligible values to
23 yW/cm2. However, Table 3 shows that the maximum, apparently
unperturbed fields inside the homes occurred in the bedrooms along the south
side of the Percival residence and were approximately 300 yW/cm2. These
values exceed all existing exposure guidelines except the ANSI radiation
protection guide level. (While it is possible that these fields were
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"perturbed" by the house wiring acting as an antenna, it is unlikely that
the elevated RF fields are due to 60 Hz current in the house wiring. We
have found that the Holaday does not respond to 60 Hz fields of the
intensity that is found near common electrical wiring.) The metal lamps in
the homes are examples of conductive objects near which elevated fields
could be found. The highest perturbed field equivalent power density was
352 uW/cm2 along a curtain rod in one of the bedrooms in the Sparks
residence. Towel racks, metal door and window frames, and curtain rods
proved to be good indicators of areas where the local electric fields "would
be elevated.
Miscellaneous
At site 3 the Holaday meter did not experience the multiple-frequency
error evident at other sites, because there was a single dominant FM signal
at this point (24 dB above the next highest peak). The FOISD and Holaday
agreed very well in the comparison at this point, their ratio being 1.04.
The Holaday was a good indicator of actual field strength at site 3;
therefore, we decided to look at the FOISD support structure's effect on the
FOISD values by using the Holaday to measure the electric fields with and
without the support structure present. The structure consists of a wooden
tripod topped by a 10 cm diameter flat metal plate, and a metal adapter
which supports a wooden post and platform on which the plastic gimbals sit.
The distance from the flat metal plate to the center of the FOISD antenna is
about 51 cm. Data were taken with this 51 cm structure both in place, and
removed. The point of measurement in both cases was the center of the
FOISD's gimbals, with the FOISD removed, of course. With the support
structure in place the Holaday meter read 330 V2/m2 (87.5 yW/cm2),
Without that structure perturbing the field, the value was 380 V2/m2
(100.8 yW/cm2).
These data suggest that the FOISD values, and also the Holaday's
multiple-frequency correction factors, should be altered. Using these new
data, the Holaday correction multipliers would range from 0.61 to 1.31 over
the entire mountaintop. However, a few considerations caution against this
change. First, when the FOISD was calibrated at the Las Vegas facility, it
was calibrated while resting in its gimbals. Hence the effects of a part of
the field-perturbing structure are already included in the calibration.
Second, we performed this check only once on Cougar Mountain, in part
because there were only a few sites where the Holaday meter corresponded
well with the FOISD values, and in part because there was no time to pursue
the question. The Holaday meter's multiple-frequency response and the
gimbals' effect upon the FOISD response underscore the fact that not only
the Cougar Mountain RF environment, but also the techniques by which that
environment might be measured are quite complex. We will study the
influence of the FOISD antenna support structure in the Electromagnetics
Branch laboratory and during future field studies.
Summary
1. With the exception of the data collected at the nine points noted in
Table 2, all data in this study were taken using a Holaday 3001 meter
10
-------
with an electric field probe. In this document, all power density
values which were derived from the Holaday values, incorporate the
instrument's frequency response correction and have been converted to
units of equivalent plane wave power density. We have not altered the
power density values to correct for the Holaday's multiple-frequency
error, but have estimated the correction factor to be between 0.53 and
1.14. We believe these factors may be used to a distance of 50 to
100 feet from the actual measurement site without introducing
significant error.
2. Non-FM band antennas are insignificant contributors to the power
densities that exist on Cougar Mountain. For hazard and compliance
purposes, FM antennas are the only significant sources on the mountain.
3. Vegetation, coniferous trees in particular, appears to be a good RF
radiation shield.
4. The greatest spatially averaged power density that we found in a
publicly accessible area was about 700 yW/cm2- No spatially averaged
value in a publicly accessible area exceeds the American National
Standards Institute (ANSI) radiation protection guide. The selection
of measurement locations will influence the distribution of power
densities found in any investigation of environmental RF exposures. If
one considers the set of locations at which we chose to make spatially
averaged measurements (Figure 3), about 5 percent of the locations in
publicly accessible areas have spatially averaged values exceeding
200 yW/cm2, the value chosen as a limit for continuous exposure of
the public by the International Radiation Protection Agency, the
National Council on Radiation Protection and Measurement (in draft)
(3), the State of Massachusetts, and Multnomah County, Oregon.
Spatially averaged values at approximately 11 percent of the locations
exceed 100 yW/cm2, a guideline that the City of Portland, Oregon, has
proposed for oublic exposure to RF radiation. Virtually all values
exceed 1 yW/cm2, the actual upper range of the exposures most people
in the nation experience (4).
5. Localized unperturbed maximum power densities exceed the ANSI radiation
protection guide in publicly accessible areas near the KPLZ tower, the
KMGI, KZOK, KMPS tower, and in the backyard play area near the Percival
residence.
6. Many of the maximum values at ground level inside the Ratelco North lot
exceed 1000 yW/cm2; a few exceed 2000 uW/cm2. These values
represent only potential occupational exposures. Although no
measurements were taken at elevated locations on the towers, there is
no question that a worker who ascends any of the FM towers (inside or
outside the Ratelco North lot) will encounter fields that exceed the
ANSI radiation protection guide.
7. All spatially averaged values near the residences we surveyed were
below 100 yW/cm2. Spatially averaged values inside the homes did not
exceed 23 yW/cm2. The maximum unperturbed value inside any home was
305 yW/cm2, while outside it 'was about 350 yW/cm2. The maximum
. 11
-------
perturbed field inside a home was about 350 pW/cm2 near a towel
rack. The maximum outdoor perturbed field was 2350 pW/cm2 near a
"chinning bar" in the playground near the Percival residence.
8. Calculated exposure values exceed the actual measured values by wide
margins in some cases. These discrepancies are :aused by: (a) the use
of a model which prudently avoids underpredicting, (b) the terrain at
Cougar Mountain which presents greater elevation angles and distances
from any given measurement location to an FM antenna than would be
encountered if the terrain were level, and (c) the dense vegetation
which acts as an RF attenuator.
9. In addition to potential health effects, residents on Cougar Mountain
are concerned about radio frequency interference (RFI). Their
electronic equipment, televisions, recorders, etc., do not function as
expected. It should be noted that FCC Rules and Regulations, Vol. 3
Part 73, Radio Broadcast Services, Section 73.318 specifies limitations
on FM radio "blanketing."Blanketing refers to a condition caused by
high field strengths, which degrades FM radio reception because of
receiver overload. The blanketing field strength defined by the FCC is
0.562 V/m which is equivalent to 0.0838 pW/cm2. The data contained
in this report (see Figures 3 and 13) illustrate that the RF levels on
virtually the entire mountaintop exceed the blanketing value. We
experienced what we believe to be an RFI problem when we were taking
data along S.E. 173rd Road near the Ratelco North lot. Despite the
fact that it was surrounded by a steel vehicle with conductive film
covering most of the window surfaces, our computer ceased to function
until we moved further from the KPLZ tower. It is understandable that
interference problems would arise in nearby unshielded homes.
10. All values presented in this report were the result of measurements
within about 10 feet of the ground. It is likely that the power
densities increase as one moves to greater heights, becoming closer to
the antennas, and encountering more of the main beams. Public access
to such elevations would be possible with the erection of multistory
buildings.
11. Introducing conducting objects to a relatively weak electromagnetic
field can cause local power densities that are many times as great as
what would be measured in the absence of the conducting object.
Exposure to such enhanced power densities is likely to occur for
significant periods of time only inside a dwelling or business. This
field enhancing effect that conducting objects, which are commonly
found in inhabited structures, have on generally weak fields, should
admonish the FCC and land use planners as they rule on high power
antenna, industrial, and residential siting.'
12
-------
Table 1. TRANSMISSION FREQUENCIES ON COUGAR MOUNTAIN BY TOWER NUMBER
FM Effective
Tower Number FM Broadcast (MHz) Radiated Power (kW) Frequency (MHz)
1
2 KIXI 95.7
KISW 99.9
3 KLSY 92.5
4 Not in use
5 KEZX 98.9
6 KPLZ 101.5
7 KUBE 93.3
8 KQKT 96.5
9 KMGI 107.7
KZOK 102.5
KMPS 94.1
10
11
12
_
(200)
(200)
(200)
(200)
(200)
(200)
(162)
(126)
(200)
(196)
_
*
_
35.700
48.180
173.375
455.025
455.125
43.580
12,410.
43.2
-
-
72.640
-
461.000
461.375
862.6375
863.3875
864.1375
864.8875
865.6375
43.26
151.985
12,470.
12,490.
12,510.
12,530.
12,670.
12,690.
72.
150.920
150.935
159.720
454.050
457.5375
457.5625
(continued)
13
-------
Table 1 (continued)
FM Effective
Tower Number FM Broadcast (MHz) Radiated Power (kW) Frequency (MHz)
12 (cont.) - - 457.5075
461.050
461.100
46r.450
461.600
461.625
461.9375
462.175
462.8625
462.9125
463.2375
463.800
464.400
464.700
464.7625
861-865 15
transmiters on
a trucking
system
960.
13 - 72.
44.
152.21
14 - - 49.520
49.580
140.050
150.920
150.950
151.595
154.040
156.500
157.590
158.700
159.660
415.050
418.950
450.6125
452.300
452.625
452.675
461.650
461.975
462.150
462.774
(continued)
14
-------
Table 1 (Continued)
FM Effective
Tower Number FM Broadcast (MHz) Radiated Power (kW) Frequency (MHz)
14 (cont.) - - 462.925
463.225
4.63.425
463.600
463.675
464.175
862.6125
862.6625
862.8125
862.9375
862.9875
863.3625
863.4125
863.5625
863.6875
863.7375
864.1125
864.1265
864.3125
864.4375
864.4875
864.8625
864.9125
865.0625
865.1875
865.2375
865.6125
865.8125
865.9375
865.9875
15 Not in Use
16 Not in Use
17 - 159.990
18 - - 152.090
19 - - 1,855.
1,915.
6,745.
6,775.
20 - 1,885.
1,895.
(continued)
15
-------
Table 1 (Continued)
FM Effective
Tower Number FM Broadcast (MHz) Radiated Power (khl) Frequency (MHz)
21 - - 47.02
47.10
.147-^08
22 - 33.160
43.
72.
150.845
152.240
159.525
159.840
462.550
16
-------
Site
) MEASUREMENTS AND BROADBAND COMPARISONS
n Microwatts Per Square Centimeter)
88-108 MHz (FM)
FOISU
Narda Holaday FOISD Holadays
1-2.5 GHz
AEL Crossed Log Periodic
2.5-13 GHz
AEL Crossed Log Periodic
2-18 GHz
WJ Ominidirectional
Vehicle Mount
2. South Gate area
of Katelco
North Lot
3. Near KQKT
4. Near Ratelco
South Lot
5. Near KMGI,
KZOK, KMPS
6. Near Percival
Residence
7. Near Lennox
Residence
81.0 56.7
0.70
83.1
760
8. Near West Gate of
Ratelco North Lot
9. Inside Ratelco 760
North
10. Near Sparks
Residence
77.5
12.2
1268
50.5
4.9
80.8
9.0
914
45.6
5.6
1.04
0.74
0.72
0.90
1.14 sak.
599
370 0.62
1561 830
0.53
0.0003 peak, 2 polarizations
.006 peak,
1 polarization
(0.000003 for 1.84-1.87 GHz
averaged, 2 polarizations)
(0.00000007 for 2.178 GHz peak,
1 polarization)
no frequency exceeding noise level
on wide band scan
(0.000007 for 6.775 GHz peak,
1 polarization)
0.00002 for 1.8S> to 1.92 GHz
peak, 2 polarizations
0.006 for 0.8b to 0.87 GHz peak,
1 polarization
-------
Table 3. INDOOR MEASUREMENT DATA
LENNOX RESIDENCE Plane-wave Equivalent Power Density
(yW/cm2)
Spatially Averaged Maximum
Living Room 2 11
Kitchen 2
Bedroom 7-9
Chinning Bar _ 117
Microscope eyepiece - 35
Office area 2
Chair 5-12
Second Floor Storage 4-5
Lamp - 14
Over table 7
Shower 2
Basement 2-12
Near radial arm saw - 129
PERCIVAL RESIDENCE
Living Room 5-12
Near sliding door to deck - 23
Door to Kitchen 12
Door frame between kitchen and deck - 70
Kitchen 7-23
Near corner of woodstove - 23
Entry Way 12-23
Master Bedroom 12
Over bed near ceiling - 59
Southwest corner - 305
Near swag lamp - 235
Daughter's Bedroom
Over bed 23
Near bed with electric blanket - 70
Near south wall - 282
Bathroom 8-12
Deck 12 23
West end 21
East end 4
18
-------
Table 3 (continued)
SPARKS RESIDENCE
Living Room
Kitchen
Window frame
Family Room
Sliding glass door frame
Master Bedroom
Metal door frame
Dressing room
Shower stall
Bedroom No. 2
Along curtain rod
Office
Filing cabinet
Window
End of curtain rod
Bathroom
End of towel bar
End of shower curtain rod
Entry Way
Utility Room
Garage
metal bar surface on door
Basement
Bedroom downstairs
window frame
Furnace room
Bathroom Downstairs
end of towel rack
Plane-wave Equivalent Power Density
(yW/cm2)
Spatially Averaged
7
1-2
1-2
1-2
1-2
2-7
2-5
1-4
2-5
1-4
8
1-2
0-1
1-2
0-1
Maximum
15
26
7
7-21
95
352
16-23
16
117
33
129
8
59-70
20
8
19
-------
VnSHON
ISLRND
LRKE
SRMMflMISH
D
COUGflR
MOUNTflIN
LflKE
YOUNGS
Figure 1. Map of Seattle Area Showing Location of Cougar Mountain.
20
-------
id
lOOpW/cm2
50 100 150 200
Meters
Figure 2. Computer Plot of Calculated Power Density Values for Cougar
Mountain.
21
-------
FM Broadcast Band
Res RH IHH kH?
I'olanzat Ions ป 3
Rverage
ro
ro
f--l- -4f-f-4-
I
B5/B8/85. 10:29 RM 28 Sons
Loot Ion: SITE 2
Processed
flntenni Used: Fiber Optic Isolated Sphencil Dlpole
Frequency Amplitude
(MHz) (dBuV/n)
32. 5 (KLSY) 134.28
93.3 (KUBCI 134.33
94.1 (KHPS) 136.47
95. 7 (KIXI) 125.53
96. 5 (KQKT) 122.91
96.9 (KEZXI 134.94
93.9 (KISH) 136.73
181.5 (KPLZ) 133.53
182.5 (KZOK) 125.38
IB?.? (KHGI) 127.91
Total Band exposure:
Power Density
CuH/cm-J)
6.9?
7.29
II. 76
8. 35
8.52
8.27
12.46
5. 98
B.38
1.64
56.74 uH/cn'2
IB Frequencies Included In the Integration.
OO
QO
G)
CD
-------
150 -i-
140 --
FM Broadcast Band
ro
u>
90
80
Ret BH - 180 hHi
Poltrlzitlons - 3
Hverige
US /Rfl yft*i 9*49 PH
DJ^DD'OJ C ! Tt rrl
Lootlon: SITE 3
Rntenni Uied: Fiber
Frequency
(MHz)
92. 5 (KLSY)
93.3 (KLIBE)
94.1 (KHPS)
95. 7 (KIXI)
9E.S (KQKT)
99.9 (KCZX)
99.9 (KISM)
IBI.S (KPLZ)
102. 5 (KZOK)
IB?. 7 (KHGI)
Totil Bind Exposure
Optic Isolated
flnplltude
(dBuV/r.)
112.86
IM.I7
113.44
113.16
144.88
131.20
109.41
114.37
110.96
IH.0?
:
ปปtซrf
1CBD
Spherlcil Dlpole
Power Density
(UH/CB-J)
B.OS
0.B7
0.86
0.BS
80.03
0.3S
0.03
0.07
B.B3
0.87
80.81 uH/cn-2
IB Frequencies Included In the Integntlon.
CS)OJ<9-U)GD(S)OJ^'LOCD
CDcncnoicDOQQOQ
Frequency (MHz)
Figure 5. Site 3 FM Spectrum.
-------
140 -i-
130 --
FM Broadcast Band
Rat BH - I08 kHz
Polarizations - 3
Rverage
> 110 --
CQ
a
ro
80
BS/BB/85. StM PM
Location: SITE 4
flntanna Used: Fiber
Frequency
(MHz)
92.5 (KLSY)
93.3 (KUBE)
94.1 (KMPS)
95.7 (KIXI)
98.5 (KOKT)
98.9 (KEZX)
99.9 (KISM)
' 181. 5 (KPLZ)
IB?. 5 (KZOK)
IB?.? (KHGI)
Total Band Exposure
Optic Isolated Spherical Dlpole
Raplltude
(dBuV/n)
136.2*
127.27
128.31
118.94
117.97
119. 89
123.38
117. 2B
I3B.B9
124.23
:
IB Frequencies Included In the
Poner Density
(uH/cn-2)
1.12
1.41
i.ea
B.2I
B.I7
0.22
8.57
B.M
2.71
8. 78
9.83 uH/cm~2
Integration.
Frequency (MHz)
Figure 6. Site 4 FM Spectrum.
-------
160 -i-
150 --
FM Broadcast Band
Ret BH - IBB kHz
Polarizations - 3
Average
130 --
120 --
ro
en
110 --
100 --
85/88/65. 6:58 PH
Laotian: SITE 5
Rntenna Used: Tiber
Frequency
(MHz)
92.5 (KLSY)
93.3 (KUBE)
94.1 (KHPS)
95.7 (KIXI)
SE.5 (KOKT)
98.9 (KCZX)
99.9 (KISH)
IBI.5 (KPLZ)
182.5 (KZOK)
187.7 (KHGI)
Total Bind Exposure:
18 Frequencies Inc
Optic Isolated Spherical Dlpole
Rupl Itude
IdBuV/n)
123.48
123.67
HS.I8
125.92
189.46
125.98
124.78
123.19
154.72
141.48
uded In the
Paver Density
(uH/cm'J)
8.59
0.62
87.36
1.84
8.82
1.85
8.78
8. 55
785.69
36.65
914.36 uH/cm-2
Integrat Ion.
Frequency (MHz)
Figure 7. Site 5 FM Spectrum.
-------
FM Broadcast Band
Res BH - 188 kHj
PoUrlntlonl - 3
Rvcrage
80
85/88/85. 7:36 PH SB Scini
Location: SITE 6
Processed
Antenna Used: Fiber Optic Itolatad Spherical Dlpola
Frequency Huplltude
(MHz) (dBuV/.l
92.5 (KlSri 136.34
93.3 (KUBE) 125.7?
94.1 (KMPS) 135.91
95.7 (KIXI) 136.45
96.5 (KQKT) 120.86
96.9 (KEZX) 135.73
99.9 (KISH) 126.94
IBI.5 (KPLZ) 124.43
182.5 (KZOK) 121.76
187.7 (KHGI) I28.8B
Total Band Exposure:
Pover Density
IB. 89
1.88
I.B3
11.72
8.27
9.92
2.BB
B. 74
8.48
8.32
45.57 uH/cnป2
IB Fraquenclei Included In the Integration.
Frequency (MHz)
Figure 8. Site 6 FM Spectrum.
-------
FM Broadcast Band
IN)
, ,
Rei BH - 108 kHz
Polarizations - 3
Aver ige
|
II
M
M
II
-^B^^^L
P^^W^
85/88/85. 8:21 PH
Location: SITE 7
Rntenna Used: Fiber
Frequency
(MHz)
92.5 (KLSY)
93.3 (KUBE)
94.1 (KMPS)
95.7 (KIXI)
96.5 (KQKT)
98.9 (KCZX)
99.9 (KISH)
IBI.5 (KPLZ)
182. 5 (KZOK)
107.7 (KHGI)
Total Bind Exposure
10 Frequencies Inc
IB8 Scans
Optic Isol
ftap 1 1 tude
(dBuV/n)
121.87
HE. 69
IM.45
115.10
131.75
123.97
116.52
115. IB
107.51
112.54
=
luded In th
Processed
ated Spherical Dlpole
Power Density
(uH/cm'2)
8.41
0.12
0.07
0.09
3.97
0.66
0.12
0.09
0.01
0.05
5.59 uH/cm-2
e Integration.
CD (S CM
GO CD C71
Frequency (MHz)
Figure 9. Site 7 FM Spectrum.
-------
FM Broadcast Band
ro
oo
Rei BH - IB0 kHz
Polarizations - 3
Average
1
|
1
'Ww^Ww
05/88/85. 9:43 Prt 58 Scans
Locitlon: SITE 8
Processed
Bntenni Used: Fiber Optic Isolated Spherical Dlpole
Frequency Amplitude
(MHz) (dBuV/m)
93.5 (KLSY) 142.34
93.3 (KUBE) 133.51
94.1 (KHPSI 126.84
95.7 (KIXII 139.81
9E.5 (KQKT) 121.48
98. 9 (KEZX) HB.76
99.9 (KISH) 138.44
IBI.5 (KPLZ) 144.74
182.5 (KZOK) 119.57
187.7 (KHGI) 119.39
Tottl Bind Exposure :
Pover Density
(uH/cซ-2)
45.44
4.73
1.87
21.18
8.37
199.34
18.58
79.84
8.24
8.18
378.81 uM/ci>"2
IB Frequencies Included In the Integration.
80
S)
CD
(9
GO
CD
Frequency (MHz)
Figure 10. Site 8 FM Spectrum.
-------
160 -i-
FM Broadcast Band
, 10
Rซ BH IBB kHi
Polirlntloni - 3
Rvenge
1
I
rfULl^^
w 'M fi fQC^jRtl
fSPffW
85/86/85. 10:33 PH
Locitlon: SITt 9
Rntenni Used! Fiber
Frequency
(MHz)
93.5 (KLSY)
93.3 (KUBE)
94.1 (KMPS)
95. 7 (KIXI)
96. S (KOKT)
96.9 (KEZX)
99.9 (KISH)
IBI.S (KPLZ)
182.5 (KZOK)
187. 7 (KHGI)
Totil Bind Expoture:
SB Sctni
Optic Iiol
Rnplltude
(dBuV/n)
ISI.67
13-1.09
131.97
149.99
119.26
M6.BE
136.73
139.29
115. BB
121. G2
Processed
ited Spherlcil Dlpole
Power Density
(uH/c.*8)
369.64
6.79
4.18
264.84
8.22
126.84
12. SB
22.52
e.ia
B.39
638.82 uH/cn'2
IB Frequencies Included In the Integration.
80
is
CD
IS
CO
IS
Frequency (MHz)
Figure 11. Site 9 FM Spectrum.
-------
CO
o
Rซ BH 188 kHz
Polirlzitloni > 3
Rviriga
CM rvi
85/18/85. 4:44 PH 58 Scini Proc.ited
LOGit Ion: SITE 7
Rntinni Uซซd: Tiber Optic Iioltted Spherlcil DIpoU
Frequency (MHz)
Figure 12. Site 7 Wideband Spectrum.
-------
Cougar Mountain Publicly flccessible Rreas
1000
OJ
<
E
u
\
3:
3
v>
c
0)
a
0)
3
o
a.
100
CO
10
id
u
a.
x
- WPD
Clt
P (i
y ฐ
i
Iraf
r Po
:), IR
tland
MMBBl
ป
>A, M
limi
issachi
-sm
Jr
,-
Les
i than
sett
m
i^v-
i
1% 0
5 St
mm-
m
f U.
and;
i
B-
S. i
rH
/
irba
.
-P
jf
^
n po
pulal
*
c
f
"f
jf
f
M
;ion ex
posed
~
^ป
>
above
1 \.
ป
W/c
n2
OJ
in oj
in
(S)
(3
C\J
C3
in
IS)
ID
(S)
GO
m
in
m
GO
en
O)
en
Cummu1 ative Percent of Measurement Locations with Spatially
Rveraged Pouier Density Values Less than Ordinate Value.
in
en
m
co en
en en
en en
Figure 13. Probability Plot for Cougar Mountain Spatially Averaged Power Density' Values in
Accessible Areas.
-------
1
1 j
1
1 1
540
1
1 i
W ! 704 ' 1
^f i ni
! i
1160* ' |
986 W =-621
-"-!
i
.63 = ^^
1
704
.
1
1361
\J Indicates tower 1
supporting FM ' 61ฐ
antennas. 1
9Dซ
O Indicates tower . 939
which does not i
support an FM | 962
antenna. i
1
610
^ Indicates | -^
instrument f&
comparison location; |
associated value is . 687
FOISO Value I
Holaday Value j
see Table 2. j 2223
j
All other values were 138S
measured with the 1
Holaday 3001 . ' 469
1
All values have been j
corrected for the 1
instrument's j 61"
frequency response 1
and have been
converted to units of |
microwatts per
squa're centimeter. L .
469
822
822 704
822 761
610 587
329 587
1
1
1
1
1
1
^/ 234 610 751 822 f22 587 915 704 '
1878 oiu
493 939
1080
1690 2113 "61
,-1690 1972
\ฃ/
1455
1033
822
1
1
1
1
.
1221 |
>2347 """ 1056
4/$S 939
>2347
1056
563
1244
763
751
> 587 751 1056 610 646 587 822
&
ฉ
0 10 20 30 40 BO 60
Feet
W=.70 \
1
1
1
1
1056 1
i
i
1
1
1
|
1
1
1
1
70 1
1
j
\
area
Figure 14. RATELCO North Lot Maximum Values.
32
-------
Cougar Mountain - RRTELCO NORTH Lot
u>
dUUU
2000
1000
^^
OJ
E
u
* 100
^/
X
M
c
0)
a
l_
Q)
1 10
1
ANS
I, f
lew i
i
Jersey
.'
stan<
ซ
Jard-
^
mt
7-
^
^^
pป
^m
ง
^
f~*
,**
*
i
- oj in ซ oj in Q o s) 03 (S) 03 03 C3 03 in GO cn in GO a
ซ oj n ^f in to I^CD cncn cncnซ
Cummulatlve Percent of Measurement Locations with Power
Density Values Less than Ordinate Value.
cn cn cn
cn cn cn
Figure 15. Probability Plot of Power Density Values at All Measured Points Inside RATELCO North Lot.
-------
RATE LCD
North Lot
469
= .70
200 228 164 218 216
Building
282
282 1
305 '
I
352^7> 305 235 235 282 157 129 94
235 |
235 I
I
i
282
792
Indicates tower supporting FM antenna.
21 1
V7 Indicates instrument comparison location;
associated value is: FOISD Value _T.Kla, "8
Holaday Value
All other values were measured with Holaday 3001.
All values have been corrected for the instrument's
frequency response and have been converted to
units of microwatts per square centimeter.
Feet
10 20 30 4O
SO 60
7O
80
141
141
127
141
Figure 16. RATELCO KUBE Enclosure Maximum Values.
34
-------
150
N 352
399
493
587
469
>2347
469 376 587 399 399 ^N 939 915 986 1033 329 329 200 176 117
821 ^^-.72
469
704
869
704
704
Indicates tower supporting FM antennas.
Indicates instrument comparison location;
associated value is FOISD Value 'see Table 2.
Holaday Value
All other values were measured with the
Holaday 3001.
All values have been corrected for the
instrument's frequency response and have
been converted to units of microwatts per
square centimeter.
Feat
10 20 30 40 SO 60 70 80
Figure 17. Maximum Values Near KMGI/KZOK/KMPS Tower.
35
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REFERENCES
1. An Automated TEM Cell Calibration System, E. D. Mantiply, EPA 520/1-84-024,
October 1984.
2. An Engineering Assessment of the Potential Impact of Federal Radiation
Protection Guidance on the AM, FM, and TV Broadcast Services, P. C.~"GaiTey,
R. A. Tell, EPA 520/6-85-011, April 1985.
3. Presented at the Annual Meeting of NCRP, Washington, D.C., April 1984.
4. Population Exposure to VHF and UHF Broadcast Radiation in the
United States, R. A, Tell, E. D. Mantiply, Proceedings of the IEEE, Vol.
68, No. 1, January 1980.
36
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GLOSSARY
Gigahertz (GHz); 1 GHz equals 1,000,000,000 Hz.
Hertz (Hz) is a. unit for expressing frequency equivalent to cycles per
second, i.e., one Hertz is defined as one cycle per second.
Kilohertz (kHz); 1 kHz equals 1000 Hz.
Maximum Value refers' to the highest power density value that can be found
in a given area based on electric field measurements, normally associated with
areas of limited extent wherein only partial body exposures might occur.
Maximum Value in a Perturbed Field refers to the maximum power density
value which we believe is caused by the convergence of electric field lines at
a conducting object. While these elevated levels are artifacts of the
conducting objects in the field and are highly localized in volume, they are
real, measurable fields.
Maximum Value in Unperturbed Field refers to that maximum power density
value which exists in the absence of any conducting object in the immediate
vicinity (i.e. a few feet). These are the maximum values found in "free
space."
Megahertz (MHz); 1 MHz equals 1,000,000 Hz.
2
Microwatt per Square Centimeter (uW/cm ); an expression for the power
density of an electromagnetic field, 1000 jiW/cm2 = 1 mW/cm2.
2
Milliwatts per Square Centimeter (mW/cm ); an expression for the power
density of an electromagnetic field, 1 mW/cm2 = 1000 yW/cm2.
Power Density is a term to describe the intensity of incident
electromagnetic radiation fields.
Spatially Averaged Value refers to our best estimate of the average
power density or typicalpower density that exists in a given location.
(i.e. the average value that exists over a vertical area of about
70 square feet.)
Rate!co refers to Ratelco Incorporated, a company which owns several
towers atop Cougar Mountain and leases tower space to broadcasters, point to
point users, land mobile users, etc.
Volts per Meter (V/m) is an expression for the strength of an electric
field.
37
-------
APPENDIX
EQUIPMENT AND CALIBRATION INFORMATION
The equipment used during the Cougar Mountain study is listed below.
Calibration data are detailed for each instrument in the following pages.
Broadband Equipment
Holaday Industries Model 3001, S/N 26026 Meter
S/N 056 Electric Field Probe
Narda Model 8616, S/N 05016 Meter
Model 8631, S/N 03026 Magnetic Field Probe
Narrowband Equipment
NanoFast Fiber Optic Isolated Spherical Dipole Model EFS-2, S/N 2927
Ailtech Singer Dipole Antenna Set Model DM-105A-T3, S/N 95414-13
American Electronic Laboratories (AEL) Crossed Log Periodic Antenna
Model APX 1293, S/N 108
Watkins Johnson Omnidirectional Antenna Model 8549, S/N 17
Hewlett Packard 8566A Spectrum Analyzer, S/N 1918A00731 (display)
S/N 1918A00220 (analyzer)
Hewlett Packard 9845B Desktop Computer, S/N 1838A02156
38
-------
u>
Holaday HI--3001 s/n 26026, E Probe s/n 056
o
i.
1_
u
m
-a
0
0.75 0.75 o 74 0.75 0.75 u-^.b 0.75
T 0.73 T "'-t- T T
0.70
0.65 0.65
0. 12
11
0 11
(i (
-L 0.12 0.12 0'13 0.12 0.12 0'13
0. 17 -L
0. 15
0.0B
88 90 92 94 96 98 100 102 104 106 108
Frequency (MHz)
Figure Al. Holaday Model 3001 Electric Field Calibration in FM Frequency Band.
-------
L.
O
L.
L.
LJ
m
TJ
Narda 8616 s/n 05016, H Probe 8631 s/n 03026
I _ _ __ ,
0
-1
0.32 0.33 0.33 0.32 0<30 0.31
..37
(I (I 0
-0.23 -0.23
0.3S
(I
(i
' -0.27
-0.16 J_ -L _L _
-0.21 -0.20 -0.21 -0.22
-I
88 90 92 94 96 98 100 102 104 106 108
Frequency (MHz)
Figure A2. Narda Model 8616 (8631 Probe) Magnetic Field Calibration in FM Frequency Band.
-------
55
PQ
O
(0
c
c
OJ
.*>
. c
CE
50
45
.01
50
100
150
200
250
300
350
400
450
500
Frequency (MHz)
Figure A3. NanoFast Model EFS-2 Fiber Optic Isolated Spherical Dipole Antenna Factor.
-------
ro
40 n
30-
m
T3
2. 20-
o
CO
UL 10-
co
C
C
-------
CO
PQ
a
id
-------
Frequency (GHz)
Figure A6. Watkins Johnson Model WJ 8549 Antenna Factor for 1-18 GHz.
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