An Investigation of Radiofrequency Radiation
Levels on Lookout Mountain,
Jefferson County, Colorado
September 22 - 26, 1086
Electromagnetics Branch
Office of Radiation Programs
U.S. Environmental Protection Agency
P.O. Box 18416
Las Vegas, Nevada 89114-8416
February 1987
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An Investigation of Radiofrequency Radiation
Levels on Lookout Mountain,
Jefferson County, Colorado
September 22 - 26, 1986
Prepared for the
Office of Engineering and Technology
Federal Communications Commission
through Interagency Agreement RW27931344-01-0
Electromagnetics Branch
Office of Radiation Programs
U.S. Environmental Protection Agency
P.O. Box 18416
Las Vegos, Nevada 89114-8416
February 1987
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EXECUTIVE SUMMARY
During the week of September 22, 1986, Environmental Protection Agency
and Federal Communications Commission personnel Investigated radlofrequency
radiation Intensities near the Lookout Mountain antenna farms, west of Denver,
Colorado. Typical power densities near several area residences did not exceed
100 yW/cm^. The highest value found near the towers along Cedar Lake Road
was 580 yW/cm^, which Is below the 1000 yW/cm^ FCC guidelines. However,
near the base of the KYG0-FM tower, a 10,000 yW/cm^ value was found and
power densities exceeding 1,000 yW/cm^ were measured over a large area. The
areas exceeding the FCC guidelines are 1n a residential area and are
accessible to the public. EPA urges the FCC to order KYG0 to correct the
problem as soon as possible.
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TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY 1
TABLE OF CONTENTS 1 i
PARTICIPANTS 11 i
BACKGROUND 1
EQUIPMENT 1
PROCEDURE AND RESULTS 3
Cedar Lake Road 3
Spectrum Survey 3
Cedar Lake Road Measurements 4
Measurements Near KOSI-FM 6
Measurements Near KYGO-FM 7
Measurements Near Other Lookout Mountain Towers 8
Community Measurements 8
DISCUSSION 9
CONCLUSIONS 11
REFERENCES 12
FIGURE
TABLES
APPENDIX A, ZOOM DATA FILES
APPENDIX B, EQUIPMENT AND CALIBRATION INFORMATION
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PARTICIPANTS
Environmental Protection Agency
Office of Radiation Programs, Las Vegas Facility
Richard A. Tell, Chief, Electromagnetics Branch
Edwin D. Mantlply
Paul Wagner
Region VIII, Radiation Programs Branch
Carl V. Peterson
Federal Communications Commission
Office of Engineering and Technology
Robert F. Cleveland, Jr., Physical Scientist
Denver Field Office
Dennis P. Carlton, Engineer 1n Charge
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BACKGROUND
Lookout Mountain 1s the location for broadcast antennas for many of the
television and FM radio stations that serve the Denver area. The number of
stations and their close proximity to one another and to residential areas
make the Lookout Mountain antenna farms unusual. Table 1 lists these stations
and their frequencies. Figure 1 shows the location of stations on a map of
the Lookout Mountain area. Interference to consumer electronic devices and
subsequent concern over possible health effects led the residents and the
Jefferson County Planning Commission to request a survey of radlofrequency
(RF) radiation levels on Lookout Mountain 1n 1983. That survey was conducted
In 1983 and 1984 and found no locations where the RF Intensity exceeded the
American National Standards Institute RF protection guide of 1,000 yW/cm2
(1). However the study was limited by the fact that permission was not
obtained to Investigate the RF levels on private property near some broadcast
antennas. In 1986, residents contacted the Federal Communications Commission
(FCC) seeking a more comprehensive study. The FCC consulted EPA, and EPA
found that modeled power densities near the base of the KYGO-FM tower
approached 10,000 pW/cm2. The earlier study could not corroborate or refute
this prediction since the owners of the property surrounding the KYG0 tower
(KYG0 does not own the property) had not been reached to grant EPA permission
to conduct measurements on their land 1n 1983 and 1984. Because the projected
power density near KYG0 was so high and because the accuracy of the
calculatlonal model had been verified with measurements In other locations,
EPA Electromagnetics Branch personnel traveled to the Denver area to conduct a
study on Lookout Mountain during the period September 22 to 26, 1986. This
study was conducted at the request of the FCC under the provisions of an
Interagency agreement between the FCC and the EPA. Accordingly, FCC personnel
were present and assisted In the study.
EQUIPMENT
RF field strength 1s usually measured using broadband Isotropic electric
or magnetic field strength meters, or tunable field strength meters connected
to appropriate antennas. Broadband equipment Is used to determine the total
RF field at a point while narrowband equipment provides details of the RF
field Intensity at any particular frequency. This study employed both types
of equipment.
For automated, narrowband measurements, two antennas were used. A
NanoFast Fiber Optic Isolated Spherical D1pole (FOISD) was used for
frequencies from 10 kHz to 700 MHz. A Watkins Johnson omnidirectional
blconlcal antenna (OMNI) was used for frequencies above 500 MHz. Both detect
electric fields and both are linearly polarized antennas. The axis of each
antenna was oriented at 55° from the axis of its support mast. With this
orientation, one can place the antenna in each of three orthogonal positions
by rotating the support mast to three azimuths, 120° apart. Each OMNI and
FOISD data value presented In this report 1s the result of three orthogonal
measurements. All OMNI measurements were made with the antenna on a
fiberglass mast above the roof of the measurement vehicle at a height of about
12 feet. Some of the FOISD measurements were also made at this height, but
others were made at various heights between 1 and 8 feet above ground.
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RF power directly proportional to the electromagnetic wave power density
was conveyed via coaxial cable from the OMNI to a Hewlett Packard 8566A
spectrum analyzer and from there to a Hewlett Packard 9845B computer. The
computer applies antenna factors, combines the three orthogonal spectra and
stores the results on disk.
In contrast to the Watklns Johnson OMNI antenna, the NanoFast FOISD does
not conduct RF power directly to the analyzer. The conventional RF coaxial
cable would act as part of the antenna Itself and decrease the accuracy of the
Information collected by the FOISD at lower frequencies - particularly In the
AM radio band. To avoid this source of error the FOISD does not use
electrically conductive coaxial cable but rather a fiber optic cable which
conducts light Instead of RF power. The voltage that the electric field
Induces across the two halves of the FOISD Is used to amplitude modulate a
light signal. This light 1s conducted to the Inside of the measurement
vehicle via a fiber optic cable. The light signal 1s demodulated back to an
RF signal, and fed to the spectrum analyzer via coaxial cable. Then, as with
the OMNI antenna, the analyzer delivers frequency specific Information to the
computer for processing and storage.
Two computer programs were used to process the Information supplied by
the spectrum analyzer. The first, DRIVER, has been used for several years by
the Electromagnetics Branch for similar field studies. It 1s especially
useful for measuring peak spectra like those associated with radar and paging
systems. Those measurements that were processed with the DRIVER system are
Identified with file names beginning with "I". The second program, ZOOM, was
developed recently to allow more rapid and accurate measurements at
predetermined frequencies. The measurements made using ZOOM are Identified In
the report with file names beginning with "Z". ZOOM was tailored before the
study began to look only at the eight FM and six TV frequencies that are
broadcasting from antennas on Lookout Mountain. These frequencies are the
main consideration 1n this study (see Procedures and Results). The data
collected with ZOOM are listed 1n Appendix A by file name.
Several different broadband Instruments were brought for the Lookout
Mountain study because this area presented a complex electromagnetic
environment that could affect broadband Instruments to extents that were not
simple to predict. Bringing a variety of meters whose responses could be
evaluated on Lookout Mountain would allow the study to be completed even If
the limitations of some of the Instruments made their use Impractical for the
Lookout Mountain measurements. Three Holaday Industries field strength meters
with electric field probes, one Narda magnetic field probe/meter system, two
Narda electric field probe/meter systems, and one Instruments for Industry
(IFI) electric field meter were used. The Holaday and Narda probes are
Isotropic. The IFI unit detects only one polarization at a time and must be
reoriented If three orthogonal measurements are necessary. These systems were
calibrated at the Electromagnetics Branch laboratory during the summer of
19B6. In addition, a Holaday Industries data logger was used to store and
reduce large amounts of data for spatial averaging of RF levels. Appendix B
contains more detailed Information on the equipment and calibrations.
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Although all the antennas used 1n the Denver study sense either electric
or magnetic fields, the data presented here have been converted to
conventional units of plane-wave equivalent power density.
PROCEDURE AND RESULTS
The Denver area measurements can be sorted Into four categories: those
conducted around the Cedar Lake Road circle near the Lookout Mountain towers,
those near KYGO-FM, those at other nearby towers, and those near residences or
public attractions. Each will be addressed in turn.
Cedar Lake Road
Spectrum Survey
The top of the access road leading from Cedar Lake Road to most of the
Lookout Mountain towers 1s the highest point topographically in the area. Its
elevation allows the best line of sight to the nearby antennas, and therefore
measurements were made at this location 1n several frequency ranges In order
to establish which bands were major contributors to power density on Lookout
Mountain. These data are listed In Table 2. All these data were obtained
with the antenna (FOISD or OMNI) mounted above the measurement vehicle. All
values for broadcast frequencies represent average power densities. Values
for land mobile, two-way radio, and radar frequencies are peak power
densities. The peak radar value should be multiplied by the duty cycle of the
pulse (determined from repetition rate and width) and the rotational duty
cycle to obtain true average values for comparison to RF exposure guidelines.
Typically these duty cycles are 0.001 and 0.01 respectively so the peak value
would be multiplied by 0.00001 to obtain a typical average power density for
the radar beam. Once this factor Is applied, the radar power density Is among
the lowest 1n Table 2. Similarly, the power densities for land mobile and
two-way radio would be reduced If the duty cycles for signals In these bands
were Incorporated; however, because even the peak values 1n these bands were
relatively low and because determining duty cycle would be very time
consuming, these peak power densities were not adjusted to reflect the lower,
average values.
The power densities 1n Table 2 confirmed expectations that broadcast band
sources, particularly FM radio, dominate the RF environment on Lookout
Mountain. FM radio accounts for over twice the power density caused by VHF
and UHF TV on Lookout Mountain. This Information justified deleting all bands
but radio and TV from further detailed Investigation.
The data In Table 2 also provide quality assurance checks between
antennas and between data reduction programs. Four bands were evaluated using
both the DRIVER and ZOOM programs. The difference between the reported power
densities In each band using the different programs ranged from 1 to about
2.5 dB, a reasonably good comparison for programs developed for different
purposes. The ZOOM program was developed recently to Increase the speed and
accuracy with which measurements could be made at a set of predetermined FM
and TV frequencies. The primary reason for greater accuracy 1n the ZOOM
program 1s Its use of narrow frequency ranges and the more accurate 1 dB per
division display mode on the spectrum analyzer, rather than wide frequency
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ranges and the 10 dB per division display mode as used In DRIVER. ZOOM Is
designed to provide high accuracy 1n predetermined narrow frequency bands.
DRIVER Is better suited to studying unknown RF environments with widely
disparate field Intensities using the analyzer's wide dynamic range
(10 dB/dlv1s1on) and its broad frequency range display. The ZOOM program was
used for the remainder of the narrowband measurements In the Denver study.
A comparison between the data collected for UHF-TV Channel 31 using the
DRIVER program shows a difference of less than 2 dB, between values obtained
with the FOISD and OMNI antennas. This Is probably due to the difference 1n
the heights of the two antennas, causing them to Intercept different electric
field Intensities along the short wavelength standing waves.
Cedar Lake Road Measurements
Narrowband measurements provide useful information concerning the
particular frequencies that contribute to the power density at any location.
However, narrowband antennas remain cumbersome to use, requiring a heavy base
for support and three orientations for every measurement. They are not
practical for Investigating large areas to find locations of elevated power
densities. The lightweight, Isotropic, broadband Instruments meet this need.
Broadband Instruments are not ideal, however, suffering from limitations that
may be Important 1n the presence of low frequency fields such as AM
broadcasts, and multiple frequency, strong fields such as the FM and TV
spectra on Lookout Mountain. Nevertheless, broadband equipment is used In
order to help evaluate the RF environment In a timely manner. The question Is
how much faith, If any, should the investigator place In the data obtained
with broadband equipment. To answer this question, six comparisons were made
between the values obtained with the FOISD and the data collected with a few
broadband survey instruments. The FOISD was considered the reference standard
for these comparison measurements.
The comparison procedure consisted of the following steps. A Holaday was
used to probe the area around a measurement site to locate the maximum electric
field value. The FOISD was then placed at the point of the highest
E-fleld value to obtain the reference field value at that point. After
measuring the field with the FOISD, the FOISD was removed from Its supporting
mast and the electric field probe of a broadband Instrument was placed where
the FOISD had been. These comparisons were made using the moveable FOISD base
which allows measurements to be made close to the ground.
One of the survey Instruments used In this comparison was a Narda
magnetic field probe. The team did not have a magnetic field narrowband
antenna system that could serve as a reference standard for this Instrument as
the FOISD had for the broadband electric field meters. Instead, the team used
the FOISD as the reference as follows. Once the maximum electric field had
been quantified and the FOISD had been removed, the area directly above and
below the E-fleld maximum location was probed with the Narda 8616 meter and
8631 magnetic field (H-fleld) probe to find the H-fleld maximum associated
with the standing wave. The E- and H-fleld maxima were then converted to
units of plane wave equivalent power density for comparison.
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Table 3 presents these comparison data for locations around Cedar Lake
Road as well as for one additional location near the KYGO-FM tower, about
one-third of a mile from Cedar Lake Road. The data collected near KYGO will
be discussed later. The third column of Table 3 shows the power densities
measured with the FOISD at six locations around Cedar Lake Road. None of the
values approaches the 1000 yW/cm2 American National Standards Institute
Radlofrequency Radiation Protection Guide. This standard has been adopted by
the Federal Communications Commission (FCC) for administrative use as a guide
1n the processing of license applications (2). However, near the KOSI tower,
the power density exceeds the most stringent value (100 yW/cm2) being
considered by EPA (3) as 1t evaluates options for the protection of the
general public from RF radiation exposure.
The data 1n Table 3 are listed 1n three categories defined by the
frequency responses of the broadband instruments of Interest. The first
category Includes all the frequencies used by broadcasters on Lookout Mountain
(55 MHz to 578 MHz) Including UHF Channel 31. Because broadcasters dominate
the spectrum on Lookout Mountain, the FOISD values listed here are, for
practical purposes, the total power density that one would find at these
locations. The Holaday meters are designed to measure electric fields at all
these FM and TV broadcast frequencies, so the Holaday data can be compared
with the total power density FOISD values listed 1n the third column. With
one exception, all the differences between the Holaday and FOISD values are
less than 2 dB. The average deviation is less than 1 dB, showing good
agreement for broadband meters 1n field measurements.
The second category, described on page 2 of Table 3, consists of data for
frequencies below 200 MHz. This Includes FM and VHF-TV. Two Narda probes and
the IFI meter operate 1n this range. The FOISD value listed In this category
Includes the power density from all the Lookout Mountain broadcasters except
Channel 31, which at 575 MHz 1s beyond the recommended range of these IFI and
Narda broadband Instruments. Comparisons between the FOISD values and the
numbers reported by the Narda and IFI meters show good agreement 1n most
cases. However the use of the Narda and IFI meters was limited by other
considerations. When the IFI meter was used at Location B, 1t responded
erratically, making an accurate reading Impossible. The cause of this problem
may have been a sensitivity to frequencies outside the design range for the
meter such as the 575 MHz Channel 31 signal. Like the IFI, both Narda probes
1n category two responded accurately, but the Narda probes suffered from a
zero-drift problem. This drift makes 1t difficult or Impossible to obtain
reliable data at relatively weak RF field levels. These problems led the team
to abandon these Instruments for routine measurements throughout the remainder
of the study.
The third category 1n Table 3 Includes data for frequencies only above
300 MHz. The only broadcast source on Lookout Mountain that operates above
300MHz 1s KDVR-TV, Channel 31. The FOISD column in this category therefore
lists only KDVR's power density. The only broadband Instrument that the
Investigators had for which the operating range extends from 300 MHz upward,
was the Narda 8621 E-fleld probe and meter. The sensitivity of the Narda 8621
1s such that the relatively low power densities 1n the area could not be read
reliably on the 8621 meter. Hence no Narda 8621 broadband meter data are
Included 1n Table 3.
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The narrowband measurements made along Cedar Lake Road were useful for
Identifying the sources of the RF exposure and for evaluating the response of
the broadband Instruments. Based on this information, the team decided to use
the Holaday meters to study typical exposure levels and to search for
localized areas of elevated Intensity.
The Holaday HI-3320 data logger was used with the Holaday HI-3001 meter
(S/N 26046) to evaluate typical power densities along Cedar Lake Road. The
data logger stores Information from the meter at a rate of four values per
second. At the conclusion of the sampling period, the logger reports the
maximum, minimum, and average values that 1t recorded. For this part of the
study, the Cedar Lake Road circle was divided Into eleven segments of
approximately 300 feet each. The endpolnts of these segments are Identified
as locations A through K on Figure 1. The data were obtained as one of the
Investigators walked each of the segments, while continuously scanning with
the Holaday probe from near ground level to a height of about eight feet. The
data gathered 1n this way represent the spatially averaged power densities
along Cedar Lake Road. Table 4 presents these data. None of the average
values exceeds the FCC guideline or any standard that has been officially
adopted or Is being considered In the United States. Two of the maximum power
densities exceed one of the proposed EPA guidance options (100 yW/cm2), and
one exceeds other standards (200 yW/cm2) published by the National Council
on Radiation Protection and Measurements (NCRP) (4) or the International
Radiation Protection Association (IRPA) (5).
Measurements Near KOSI-FM
Both the narrowband measurement made near the base of the KOSI tower and
the broadband spatially averaged survey of Cedar Lake Road indicated that the
highest levels along the Cedar Lake Road loop were near the KOSI tower.
Further measurements were made near the KOSI tower using the Holaday meter
(S/N 26046). The highest value that could be found was about 580 yW/cm2 1n
a limited area about 3 to 5 feet In front of the KOSI gate. This value does
not exceed the FCC guideline, but It does exceed the nonregulatory 200
yW/cm2 NCRP and IRPA standards. The Investigators searched for the greatest
distances from the KOSI tower at which 200 yW/cm2 power densities could be
measured, and found that 200 yW/cm2 values were measurable out to a radius
of about 27 feet centered on the KOSI gate. Since the surveyor searched for
the greatest radius at which the 200 yW/cm2 value could be found, even In
localized areas, 1t follows that the power densities Inside this semicircle
did not always exceed 200 yW/cm2. To estimate the typical values Inside the
200 yW/cm2 contour line, the surveyor again used the Holaday meter connected
to the Holaday data logger, and made several traverses until he was confident
that the power densities within the 200 yW/cm2contour had been thoroughly
sampled. This process was repeated to evaluate Its reproducibility. The
average power densities for the trials were 215 yW/cm2 and 211 yW/cm2.
The minimum values were 35 yW/cm2 and 24 yW/cm2. The maximum values were
494 yW/cm2 and 430 yW/cm2. These data indicate that the typical power
density averaged over the entire area within the 200 yW/cm2 contour does
exceed 200 yW/cm2 although the power density at any particular location
could be much higher or much lower. The generality of this correlation
between average value within the boundary of a contour line and the value of
the contour line Itself has not been established.
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One additional measurement was made to evaluate KOSI. Since the KOSI
antenna Is mounted close to the ground on a mountain slope, structures further
up the slope could be In the main beam of radiation. A cursory Inspection
suggested this could be the case at a house painted green along the access
road to the transmitter buildings on Lookout Mountain. A survey of the deck
of this house using the Holaday (S/N 26046) found power densities to be
generally between 50 and 100 yW/cm2. These levels are well below the FCC
guldel1nes.
Measurements near KYGO-FM
The KYGO-FM antenna Is about one-third mile from the Lookout Mountain
antenna farm. It differs from other antennas 1n the area because the KYGO
antenna 1s mounted close to the ground with its bottom element at a height of
about 30 to 35 feet. This prompted the investigators to survey the area 1n
the Immediate vicinity of KYGO. Near the fence at the base of the tower, the
Holaday (S/N 26046 with 103GR probe) reported 10.35 mW/cm2 (10,350 yW/cm2)
and the Narda magnetic field system read 9.5 mW/cm2 (9.500 yW/cm*). A
typical value around the fence was 4.5 mW/cm2 (4,500 yW/cmO based on the
Holaday and 4.4 mW/cmz (4,400 yW/cm2) as reported by the Narda. The
electric and magnetic field data corroborated one another and confirmed that
power densities ten times the FCC guideline could be found In publicly
accessible areas near the KYGO tower. The lower typical value remained a
factor of four over the FCC guideline.
These data led the Investigators to map the distances and bearings from
the tower to the 1000 yW/cm2 and 200 yW/cm2 contours. Table 5 presents
these data. The locations of the 1000 yW/cm2 power density were Identified
with the Holaday (S/N 26046) electric field meter. These locations were
confirmed with magnetic field measurements using the Narda 8631 probe. The
1000 yW/cm2 locations found with the Narda were within about five feet of
the locations found with the Holaday. The 200 yW/cm2 power densities were
located using only the Holaday. The 1000 yW/cm2 nower densities extended to
approximately 30 feet from the tower; 200 yW/cm2 values were usually found
at 50 to 70 feet from the tower. To be certain that KYGO was responsible for
the elevated power densities, a FOISD narrowband measurement was made near the
KYGO transmitter building. This measurement, saved as file Z0IXJN and
summarized In Table 3, showed that KYGO was responsible for 99.7X of the FM
and TV power density at the location of the measurement.
The base of the KYGO tower 1s fenced, but most of the area within the
1000 yN/cmz contour Is not. The KYGO tower 1s located 1n a complex of
buildings where some people live throughout the year and where seasonal,
residential workshops are held to teach square dancing. Many people could
therefore visit areas where power densities exceed 1000 yH/cm*. The main
building of the compound Is located within about 100 feet of the KYGO tower.
The team found maximum power densities of 59 yW/cm2 1n the laundry room,
approximately 100 yW/cm2 In the commissary and outside the dining hall, and
up to 300 yW/cm2 on the patio/deck. Electric and magnetic field
measurements made outside a dormitory (the "Tlltln' Hilton") near the tower
found 40 to 50 yW/cm2 power densities.
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Finally 1t 1s Interesting to note the effect of different elevations (In
mountainous areas) on the power densities one records. Another narrowband
FOISD measurement (file ZOIZIu) made on top of the vehicle 1n the parking lot
at 756 Lookout Mountain Road, In the property on which the KYGO antenna Is
located, found a power density of 37.2 yW/cm2. This measurement location
was perhaps 100 feet from the KYGO tower and below the center of radiation.
The elevation Increases as one moves across Lookout Mountain Road, approaching
the apparent height of the center of radiation of the KYGO antenna. Another
FOISD measurement (file ZOIZJD) was made at this higher, but more distant
location (perhaps 200 to 300 feet from KYGO). Usually, tripling the distance
from an antenna 1n this way would reduce the power density by a factor of 9.
In this case however, the effect of greater distance was overcome by moving
higher Into the main beam of radiation. The power density rose to 85.8
yW/cm2 1n the driveway of a home across Lookout Mountain Road from KYGO.
Even at 1054 Colorow Road, approximately 800 feet from KYGO but still elevated
with respect to the base of the KYGO tower, the power density remains greater
than 1n the parking lot at 756 Lookout Mountain Road. The power density
measured near 1054 Colorow Road was 55.8 yW/cm2 (file ZOIYQx). These data
Illustrate the need to consider the relative elevations of areas surrounding a
station 1n the overall RF exposure evaluation.
Measurements Near Other Lookout Mountain Towers
Approximately three quarters of a mile from the Lookout Mountain antenna
farm are two towers which support a variety of communications antennas, two FM
antennas, and one VHF-TV antenna. KRMA-TV, KCFR-FM, and KUVO-FM are located
at the Colorow Hill site. Electric field measurements were made at this site
using two Holaday meters (S/N 26046, 26042). At the base of the broadcast
tower the power densities ranged from 2 to 124 yW/cm2. Between the antennas
and Colorow Road power densities of 350 to 425 yW/cm2 were found. Across
the road values up to 200 yW/cm2 were found.
These data prompted the team to search for the 200 yW/cm2 contour along
Colorow Road. Power densities up to 200 yW/cm2 were found along a 125 foot
length of Colorow Road, centered approximately at the door to the transmitter
building. The 200 yW/cm2 levels extended to about 12 feet beyond the far
side of Colorow Road from the transmitter building. A FOISD narrowband
measurement, made near the antennas reported a power density of 204 yW/cm2.
This file, Identified as Z0IZMF, found the major contributor to be KCFR-FM.
KUVO-FM and KRMA-TV were the next strongest contributors but together provided
only about half the power density of KCFR at that location.
At another location, one third of a mile north of the Lookout Mountain
antenna farm, 1s a smaller group of towers supporting antennas for TV and FM
stations. A survey near these towers using the Holaday (S/N 26042) found
locations where the power densities reached 273 yW/cm2. However, power
densities were usually below 200 yW/cm2, and over the entire area the levels
were generally between 50 and 100 yW/cm2, well below the FCC guidelines.
Community Measurements
The purpose of studies like this one 1s to evaluate the extent of human
exposure to RF radiation. This was a concern of many Lookout Mountain
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residents who attended an Informal gathering with the EPA and FCC
investigators on the evening of September 24. At that meeting, EPA agreed to
make limited measurements at several homes In the area. These measurements
Included collection of narrowband FOISD data at each location and broadband
survey data at several homes. For these measurements the FOISD was positioned
on top of the vehicle, and the vehicle moved to an arbitrary point along the
road or 1n the driveway. Because these locations were arbitrarily chosen, the
FOISD power densities probably are neither maxima nor minima, but are useful
because they Indicate the major source(s) of the RF radiation at each
location. Another measurement a few feet away would probably find a different
absolute power density. The broadband data were collected with two Holadays.
Table 6 presents all these data.
None of the power densities 1n Table 6 exceeds the FCC guideline. With
only two exceptions, none of the values exceeds even the most stringent RF
radiation safety guideline being considered 1n the United States. The two
exceptions, a 200 yW/cm2 power density near a trampoline spring and a
589 yW/cm' power density near a piece of metal furniture, are more
representative of the concentrating effect metal objects have on electric
field lines than they are representative of typical power densities. Electric
field Intensity can be dramatically Increased near conductive objects,
particularly 1f those objects have sharp corners. This Is why lightning
preferentially strikes lightning rods. However, the presence of another
conductive object, such as a human, can further alter the electric field,
generally lowering the Intensity near pointed conductive objects. Because of
this, the Importance of high measured electric field Intensities near
conductive objects 1s controversial. Traditional thinking on this subject Is
that relatively high, localized fields, near conductive objects where the
surrounding field is substantially less, do not cause energy absorption rates
1n tissue that would normally be associated with whole-body exposures to
fields of the same high values.
In order to place these values into perspective, two measurements were
made In an area that 1s relatively distant from the Lookout Mountain
antennas. At the end of the 700 block of Chimney Creek Road 1n the Genesee
residential area, power densities from Lookout Mountain broadcasters and from
Mount Morrison broadcasters (located near Genesee) were measured with the
FOISD. At this location, the power density from Lookout Mountain broadcast
sources was 0.2 yW/cm2 and that from the Mount Morrison FM broadcasters was
0.00015 yW/cm2. These values can be compared with the 0.005 yW/cm2 median
level to which the populations of 15 major U.S. cities are exposed (6).
Holaday (S/N 26046) measurements were also made at the Buffalo Bill grave
tourist attraction. At the overlook near the visitor center, the highest
value found was about 2 yW/cm2. At the grave Itself, power densities up to
8 yW/cm2 were measured. Typical values ranged from about 5 to 14 yW/cm2
at the overlook near the grave.
DISCUSSION
The height and topographic location of the KYG0 antenna make 1t a
convenient "field laboratory" to Illustrate two characteristics of FM
signals. The KYG0 antenna 1s unusually low on Its tower causing excessive
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power densities directly below the elements. This 1s the "grating lobe" which
points directly down to the ground and straight up Into the air from the
elements. Because the antenna 1s so low to the ground, moving a short
distance away from the tower base places one at a large angle away from
vertical with respect to the elements. The 10,000 pW/cm2 value found at the
base of the tower decreases rapidly as one moves away from the base of the
tower and out of the grating lobe. The power density falls to 1000 yH/cm2
at about 30 feet, and to 200 pW/cm2 by 50 to 70 feet from the tower. The
second point illustrated by KYGO 1s that In a mountainous area, one cannot
rely on such a rapid reduction 1n power density with distance because the
measurement locations may be moving up Into the main-beam of radiation.
Additional data collected near KYGO actually show an increasing power density
with distance from the antenna as the measurement location moves closer to the
main beam of radiation. RF hazard investigators should be aware of this
property not only In mountainous terrain but also 1n urban environments where
the main beam of radiation may be Intercepted by nearby tall buildings.
A surprising finding In Table 3 Is that the Holaday electric field meter
reported values that were below the actual (FOISD) value. While the Holaday
data in Table 3 are not far from the FOISD data, the Holaday values are almost
always low. The authors' experience, however, 1s that diode detectors, such
as the Holaday, tend to overrespond rather than underrespond In complex RF
environments. Because of this, diode detectors have been considered
conservative. However, the authors' judgement In this case Is that the value
reported by the FOISD represented the maximum field 1n an area with no nearby
perturbations, while the Holaday values were collected in the presence of a
6 foot tall Individual, the surveyor, within a few feet of the probe. It 1s
likely that the presence of the person would lower the field at the probe,
particularly when the probe Is at the location of the maximum field value 1n
the area, thereby causing the discrepancy. Additional comparison measurements
1n other complex environments will help resolve the Issue. The IFI meter's
erratic response at location B and the Narda system's zero drift problems
further underscore the fact that no single meter 1s adequate for all
monitoring situations.
It Is worthy of note that the maximum value measured at the base of the
KYGO tower compares closely with that predicted by an EPA program designed for
this purpose. The program calculated a maximum power density of
9,620 yW/cm2. The maximum values measured with electric and magnetic field
meters were 10,350 yW/cm2 and 9,500 yW/cm2 respectively for a maximum
difference between theory and data of about 0.3 dB. A similar comparison
between predicted and measured values 1n an earlier study 1n Oregon, also
found approximately 0.3 dB difference. This correspondence Is encouraging
because It helps EPA and FCC decide which antennas are likely to produce
ground-level power densities that exceed the FCC guidelines. Output from this
modeling technique could be used to Identify areas of potentially high public
exposures and to select additional areas for field study. The application of
the model to other FM facilities has shown that power densities as great as
that predicted at KYGO are unusual but not unique.
10
-------
CONCLUSIONS
1. Near the base of the KYGO-FM tower power densities reach 10,000 yW/cm2
1n a publicly accessible area. This far exceeds the FCC 1,000 yW/cm2
guideline (2) for FM frequencies. The KYGO tower 1s located 1n a complex
of buildings where some people live throughout the year and where
seasonal residential workshops are held to teach square dancing. EPA
urges the FCC to order KYGO to correct these extreme values 1n publicly
accessible areas as soon as possible. The few measurements made Inside
the main buldllng of the compound found no power densities exceeding 100
yW/cm2.
2. The maximum power density near the K0SI-FM tower, 580 yW/cm2, 1s below
the FCC guideline, however the spatially averaged power density within an
area of about 1,000 square feet near the tower exceeds the 200 yH/cm2
NCRP (4) and IRPA (5) standards and two of the options that EPA (3) Is
considering for RF radiation protection guidance.
3. With the exception of the area near the base of the K0SI tower, none of
the averaged power density data collected around the Cedar Lake Road
circle exceeds any recommendation that has been adopted or 1s being
considered by major organizations within the United States.
4. Typical power densities at several residences on Lookout Mountain did not
exceed 100 yW/cm2, the most stringent value that exists (7) or 1s being
considered 1n the United States although higher power densities of
limited extent can be found, particularly near field-enhancing, metal
objects. At a location more distant from the Lookout Mountain antennas,
a power density of 0.2 yW/cm2 was measured 1n the Genesee residential
area.
5. TV and FM antennas on Colorow Road produce power densities that exceed
200 yW/cm2 along a 125 foot length of Colorow Road. However, the
maximum value found near the Colorow Hill antennas did not exceed the FCC
guldeline.
6. The maximum power density measured at the TV and FM towers along Lookout
Mountain Road (one third mile north of the Cedar Lake Road area) was
273 yW/cm2. However, power densities were typically between
50 yW/cm2 and 100 yW/cm2 In this nonresidential area.
11
-------
REFERENCES
1. ANSI C95.1-1982 Safety Levels with respect to Human Exposure to Radio
Frequency Electromagnetic Fields, 300 kHz to 100 GHz, American National
Standards Institute. Available from the Institute of Electrical and
Electronics Engineers, Inc., New York, New York 10017.
2. Consideration of Biological Effects of Radlofrequency Radiation and the
Potential Effects of a Reduction 1n the Allowable Level of Radlofrequency
Radiation; Report and Order. Federal Communications Commission; Federal
Register, Vol. 50, No. 54, Wednesday, March 20, 1985; p. 11151.
3. Federal Radiation Protection Guidance; Proposed Alternatives for
Controlling Public Exposure to Radlofrequency Radiation, Notice of
Proposed Recommendations; Environmental Protection Agency; Federal
Register, Vol. 51, No. 146, Wednesday, July 30, 1986; p. 27318.
4. Biological Effects and Exposure Criteria for Radlofrequency
Electromagnetic Fields. National Council on Radiation Protection and
Measurements, Report No. 86, Bethesda, Maryland, 1986.
5. Interim Guidelines on Limits of Exposure to Radlofrequency
Electromagnetic Fields 1n the Frequency Range from 100 kHz to 300 GHz.
International Non-Ion1z1ng Radiation Committee of the International
Radiation Protection Association. Health Physics Vol. 46, No. 4 (April),
pp. 975-984, 1984.
6. Tell, R. A., and E. D. Mant 1 piy, "Population Exposure to VHF and UHF
Broadcast Radiation 1n the United States." Proceedings of the IEEE,
Vol. 68, No. 1, January 1980.
7. Portland Planning Commission 1980 Interim Radlofrequency Emissions
Standard.
12
-------
4 KPKE
A KBPI
KAZY
KW6N
Golden 2 miles
KRMA
KCFR
1KUVO
21209
21189
KCNC
KOAQ
IJSA'21109
855
'C A KOSI
851
>A*f
20969 *r
1054
Cedar Lake Road
21009
840 812
824
n)o>
758
A KYGO
ntam BoaJ.
732.
676
592
set
529
Figure 1. Map of Lookout Mountain
-------
TABLE 1. Lookout Mountain Broadcasters, Grouped by Tower
Location of Tower
Call S1an
Freauencv (MHz)
Lookout Mountain Road
KWGN-TV
57.5
KBPI-FM
105.9
KAZY-FM
106.7
Lookout Mountain Road
KPKE-FM
95.7
Colorow Road
KRMA-TV
85.5
KCFR-FM
90.1
KUVO-FM
89.3
Cedar Lake Road
KUSA-TV
189.5
Cedar Lake Road
KCNC-TV
69.5
KOAQ-FM
103.5
Cedar Lake Road
KOSI-FM
101.1
Cedar Lake Road
KMGH-TV
177.5
Cedar Lake Road
KDVR-TV
575.5
Lookout Mountain Road
KYGO-FM
98.5
-------
TABLE 2. Data Collected at Top of Access Road
to Lookout Mountain Transmitters
Power Density
Antenna
File Name
Freauencv Ranae
(uW/cm )
FOISD
I26M57
AM Radio
0.0000874
FOISD
I26N09
Low VHF TV
0.601
FOISD
ZOIZMs
Low VHF TV
0.941
FOISD
I26N14
FM Radio
6.87
FOISD
ZOIZMs
FM Radio
8.66
FOISD
I26N47
Land Mobile VHF (peak)
0.0435
FOISD
I26N19
High VHF TV
0.946
FOISD
ZOIZMs
High VHF TV
1.66
FOISD
I26N31
Land Mobile UHF (peak)
0.462
FOISD
ZOIZMs
UHF Channel 31
1.01
FOISD
I26N24
UHF Channel 31
0.603
OMNI
126006
UHF Channel 31
0.940
OMNI
126014
Two-Way Radio (peak)
0.0539
OMNI
*
5.57 GHz Radar (peak)
11.4
*The data for radar were collected by reading directly from the screen of the
spectrum analyzer as the antenna was positioned 1n three orthogoanl
orientations. These data were not processed by the computer and therefore
have no flie name.
-------
TABLE 3. Power Densities (yH/cm^) Determined with Narrowband and Broadband Instruments
Category 1. 55 MHz to 578 MHz
Location*
A. Near KDVR
B. South of KOSI
C. Near KOSI
D. Near 21109
Cedar Lake Rd.
E. 60 ft. east of
21189 Cedar Lake Rd.
later at same
location
F. Near 21209
Cedar Lake Rd.
Near KYGO
transmitter building
not at maximum E-f1eld
File
Name
ZOIVRU
ZOIHK2
ZOIWLU
ZOIWPF
ZOIWQZ
ZOIWRC
ZOIWRv
ZOIXJN
FOISD
17.1
46.5
159
75.6
48.5
48.3
22.5
1242
Holaday Holaday
S/N 26046 S/N 26038
up to 6000 MHz up to 6000 MHz
12.8
30.6
167
68.3
40.6
18.5
1072
13.9
22.3
170
65.6
44.6
20.2
976
Holaday
S/N 26042
up to 6000 MHz
12.4
29.7
159
69.4
37.2
17.4
1004
*See Figure 1 for locations of the measurement sites.
-------
TABLE 3. Power Densities (yW/cm^) Determined with Narrowband and Broadband Instruments (continued)
Category 2. Below 200 MHz
File
Location* Name
A. Near KDVR ZOIVRU
B. South of KOSI Z0IHK2
C. Near KOSI ZOIHLU
D. Near 21109 ZOIHPF
Cedar Lake Rd.
E. 60 ft. east of ZOIHQZ
21189 Cedar Lake Rd.
Later at same ZOIWRC
location
F. Near 21209 ZOIWRv
Cedar Lake Rd.
Near KYGO ZOIXJN
transmitter building
not at maximum E-fleld
FOISD
6.59
7.13
153
75.1
46.3
46.1
21.7
1242
IFI
up to 200 MHz
resonance
problems
202
88.9
55.2
49.2
1487
Narda
8631 H Probe
up to 300 MHz
could not zero
negative zero
drift
157
42.8 at 2'
above ground
55.1 at 7.5'
above ground
33.3
could not zero
Narda
8662 E Probe
up to 300 MHz
noise level
could not
zero
197
89.6
44.8
26.9
1299
Category 3,
above 300 MHz
FOISD
10.5
39.4
5.24
0.456
2.22
2.23
0.855
0.186
*See Figure 1 for locations of the measurement sites.
-------
TABLE 4. Averaged Power Density In yW/cm^
along Segments of Cedar Lake Road
Seament*
Mlnlmum
Averaae
Maximum
A to B
0.515
11.1
35.6
B to C
1.15
34.4
181.0
C to D
5.51
86.6
505.0
D to E
0.791
15.7
80.4
E to F
0.773
11.3
30.3
F to G
0
6.48
25.0
G to H
0.036
4.18
10.8
H to I
0
2.12
9.13
I to J
0
3.82
13.3
J to K
0.293
7.19
35.1
K to A
0.577
7.54
21.3
*See Figure 1 for the locations of the segments
-------
TABLE 5.
Approximate Greatest Distance and Magnetic Bearing from
the Base of KYGO Tower to 1000 yW/cm^ Power Density
Distance (feet) Bearing
27 336°
28 312°
31 212°
32 196°
33 184°
37 148°
39 145°
36 87°
30 80°
27 12°
Approximate Greatest Distance and Magnetic Bearing from Base
of KYGO Tower to 200 yW/cm^ Power Density
Distance (feet) Bearing
51 12°
70 144°
74 156°
89 (near guy wire pole) 158°
57 190°
53 210®
42 256°
50 326°
-------
TABLE 6. Residential Power Densities
Holaday Holaday
?
Location FOISD Value/File Name Serial Number Value (uW/cm )
21109 Cedar Lake Road 58.9/ZOIYN8
21280 Cedar Lake Road 10.9/Z0IY0U 26046
deck, yard generally 7.07-11.8
deck, yard maximum 23.6
trampoline spring surface, 200.0
maximum
21009 Cedar Lake Road 19.4/Z0IY0f 26046
1n front of garage, generally 23.6
on steps 11.8-18.8
on steps, maximum 23.6
porch and yard 4.71-16.5
porch and yard maximum 23.6
20969 Cedar Lake Road 7.91/ZOIYOo 26042
yard and driveway 5.0-17.4
yard and drive maximum 24.8
Inside house 5.0-24.8
Inside house maximum 49.6
deck maximum 24.8
851 Panorama Drive 4.49/Z0IY0y 26045
front yard 2.36-4.71
deck 4.71-14.1
backyard 2.36-11.8
840 Panorama Drive 5.81/ZOIYPF 26042
In front of house 0-3.7
Inside house 0-2.5
upper deck, rear 1.2-5.0
lower deck, rear 0-5.0
next to metal lounge, maximum 9.9
732 Aspen Road 5.53/ZOIYPR 26042
driveway 0-7.4
front proch 0-5.0
676 Lookout Mountain Road 11.6/Z0IYP1 26046
driveway near garage 1.2-3.5
upper deck 11.8-47.1
near metal furniture, maximum 589
-------
TABLE 6. Residential Power Densities (cont.)
Holaday
Locations FOISD Value/File Name Serial Number
561 Columbine Avenue 5.61/ZOIYPt 26042
driveway
back porch
S.E. corner of house
back yard
front porch, away from KYGO
529 Parkview Avenue 7.88/ZOIYP2 26046
driveway
near wood fence
front deck and back yard
near metal furniture, maximum
812 Aspen Road 4.57/ZOIYQT 26042
road above house
drive and parking area
deck and stairs
side of house
front of house
592 Aspen Road
824 Aspen Road
756 Lookout Mountain Road
1054 Colorow Road
Across road from 756 Lookout
Mountain Road
24.0/ZOIYPe
8.14/ZOIYQe
37.2/ZOIZIu
55.8/ZOIYQx
85.8/ZOIZJD
Holaday
Value (uW/cm^)
0.5-11.2
1.2-9.9
12.4
1.2-16.1
1.2-6.2
1.2-4.7
4.7-9.4
2.4-4.7
47.1
1.2-9.9
0-3.7
0-3.7
1.2-7.4
0-2.5
Genesee, end of 700 block
of Chimney Creek
0.237/Z0IYRS (Lookout Mountain Stations)
0.00015 ZOIYRq (Mount Morrison FM Stations)
-------
APPENDIX A
ZOOM Data Files
-------
F l 1
'H Pii
FM Radio Station Measurewrn1^
T (i t a 1
Antpnn^
E 1 e< tru
Total Power Density
P o w
( rl h m )
(rifcn)
(dPn)
(dUn)
(dFO
( d B i) V / m )
C n U - i m " 2 )
KUVO
89
3
-43
34
-37-
75
-3ft
0 4
-31
4C.
36
45
1 12
00
0 /) ; ¦ i! 9
KtJFR
90
1
-32
9ft
--28
95
-30
70
-25
8 0
3ft
4' *
117
ft 5
154 4 2
KPKE
95
n
t
-52
81
-7.7
4ft
-48
2ft
-37
on
36
45
1 Oft
45
01 I 7,>
k yen
9li
5
-17
34
-13
73
- 15
75
-1 0
58
3ft
4r.
1 *2
R7
13190
K08T
i 0 i
i
-26
51
-28
37
-41
79
-24
25
36
45
119
20
22(! 44
KdAQ
1 03
s
-39
15
-36
89
-44
10
- 34
38
3ft
45
109
07
025 44
KPP J
105
9
-4?
45
-33
3?
-42
PR
-32
35
36
45
11 1
1 0
(i 3 4 1 4
KA7Y
1 06
7
-42
95
-3ft
03
-30
48
-29
D'.>
f ~ l
36
45
114
23
0 7 01 r<
bH'-y,*
TV Video Mp.i^urewf'nf1
Lai ]
Sign
Frpqupnry
(MHz )
Px
(dhn)
P V
(dPn >
P /
(d F< n 1
T o t <>l
P owpr
An 1 t-nn
Total Power Density
f" I r>( t r I (
F ip|'1
KUCN
55
25
-39
25
-44
73
-47
0 V
-37
64
36
45
1 0 1
81
KCNf!
67
24
-35
04
-36
61;
- 38
19
-31
68
3ft
45
1 07
77
KRMA
83
24
-22
4 0
-27
68
-32
01
-20
92
36
45
118
53
KMCH
175
25
-24
82
-23
33
-19
63
-17
25
3ft
45
122
20
KU5A
187
24
-40
9ft
-34
80
-35
38
-31
54
3ft
45
j 07
91
KIH-'K
573
?5
-J 1
DC
t }
-9
97
- 1 0
22
-5
67
37
61
134
93
P (> ' u v
I>pn s M y
( i, U' / i m"2 i
Oil"! 0 ?
0 1
1 8 V Oft
4 ¦\ 0 (i 7
n 1 638
f< 2r.935
F<
4 dF* ^.nbtractrd fr om p <%a l< f- 1 p< t r i ( field to obtain RMS p 1 p< 1 r i ( f i <•> I d
TV Audio MeasiTPwen ts
T o t a J
Antenna
F1 f ¦ r t n '
Call
Frpqupnry
Px
Py
P 7
P o wpr
F ar t or
r i p l d
Sign
(MH 7 )
(dhw)
(dPn)
(dpM)
(dHci)
i i y
\ ijW/cm' 2)
0 0,'.ii/
0 n5H5
02' .57
1 Vft84
0 D n 1 V
2 1«>97 6
Total Power Density
43l>24
IV 4. FM Powrr Dpru, jty
JV OUi.'-l
-------
File Nawp ZriJWK?
FGI5D Full Scale Setting 50(V/m)
0 9.'23/8ft
1 n
Af.
FH Radio Stataon Measurements
To fa 1
An I pnnr*
E] pc t
•" 1 L
Po
Tall
Frequ^ncy
Px
Py
P 7
Power
Factor
Field
Pf'li
¦, i i y
S nj ri
(MM/ )
(dhr>)
< dBn >
(dUn)
1 P3
Sfi
ftOSSP
K ("i f> 1
ioi
1
-21
3?
-27
ft3
-2ft
70
-19
49
44
35
131
86
4
(I.SV44
KG AO
103
s
-3?
81
-39
5ft
-27
54
-?ft
P0
44
35
1 PS
15
P.67 34
KHP 1
i OS
9
-43
63
-41
13
- 44
40
-3B
05
44
35
1 13
30
0'>ft7 1
KAZY
106
•7
/
-3ft
PV
-39
8;»
-43
03
-34
10
44
35
117
PS
1 4 079
Total Powr-r Density *"> 77;)u/:
TV Video H^ar.urewent1-
Total
An t enn-a
E 1 er
I r i c
P (i U' i -7
Cr". 1 1
F rpq upnry
P x P y
P
7
P o wpr
Foe t or
F i r
1 d
Dt-»n-» j 1 y
S l g n
(MH? ;
(d b m ) (d P m )
(dPfO
(11 !-< n >
(ripii'
M ')
( UI'1 r n * 2 )
KUlJlM
55 23
-36 45 -3S 58
-35
71
-31
1 3
44 35
1 1 ft
t i
11 1P0
k r n n
67 24
-37 37 -39 3 0
-P9
21
-2K
24
44 35
119
J 1
P1 61 P
K R MA
83 24
-45 a?, -42 73
-45
5 0
-39
58
44 35
107
/ '
tn '.f'.V
KMGH
175 25
-2? 9 4 -27 54
-PR
41
- 23
75
44 35
1 P3
60
6.0 701
KI ISA
187 24
-37 5? -4 0 94
-33
n't
' 4.
- 31
ft h
44 35
1 1 5
69
0 9(130
KDVk
573 25
-V 2 0 -13 29
-15
07
- 7
(13
45 51
141
48
37 PR610
Total I
3owpr
Dpnc. 11 y
3H 331 • ^ft
*
4 dP subtracted frori p^dk i
f?1 ec tr lc
f i el d
to obtain
RMS
p ! r«c
f r i c field
V Audio
hea c> u r rnen t <"¦>
Total
An t rnn' 39VaO
TV 4. FM Powpr Density 4f- 51
-------
FiIp Name ZDJULu
FdJSD Full Scale Snttinq 1()0(V/m)
09/23/86
1 l 46 Aii
FM Radio Slati en hPt^urenenV.
Total
An tenna
Elpr tr i r
Cfi L1
Freq dpiic y
Px
Py
Pr
P ower
Factor
Fie ] rt
R i gn
(MHi >
(dhn)
(dPn)
(riRn)
< dPn >
(dP)
< dPuV/n)
KUVO
89 3
-59 37
-58 r>0
-54
0"7
/ W
-51
98
50
4 0
10S 42
KHFR
90 1
-54 39
-54 7>'>
-l".1
25
-4H
39
50
4 ft
109 01
KPKF_
95 7
-42 8#.
-42 33
-43
-38
06
50
40
1 1 9 34
KYUO
90 r>
-45 5 0
-56 64
-54
41
-44
35
50
40
11 05
K()R[
101 1
-18 57
-19 99
- 1 1
06
-9
90
5 0
4 0
147 50
KfiAQ
J 03 5
-46 43
-53 37
-45
36
-42
48
5 0
40
114 92
K BP I
1 OS 9
-39 93
-38 38
- 44
1 7
-35
4S
50
4 0
121 9c;
KA7Y
1(16 7
-40 97
-4? 68
- 46
77
-3R
1 (l
so
40
11V 30
P o i J <" r
Deni t y
< Ml.' '< ma2 )
0 (i^VS
021 14
">'/'/ f"
t t * • t \ j
0L">7,4V
149 06V2,'
tu*23(i
41 '>61
22590
Total PouF'T Dpnciiy
IMi 10 4^3
TV VjcIpo MPrTSHTPMPr t«S
Total
An 1 pnFi.i
~
F I fc \ r 11
P o w(*r
Cdl ]
Frer| upnr y
P
X
Py
P?
P o wpr
F^r 1 or
F j p
1 d
I>f'nr j i y
S 11 f n
(MHr >
(d b m )
< d Pn)
(dPn)
(<1Hn)
(tip)
(dPn1
V /fl >
< uW/r m'2)
KWGN
55 25
-42
70
-48 46
- 42 3D
-39 0 0
50 40
114
4 0
ov;-9t«
K [,NH
67 24
-41
36
-43 55
-40 44
-36 83
5 0 4 0
1 1 6
S?
1 20 4 9
KRMA
83 24
-46
19
-SI M
-48 21
-43 36
50 40
ill)
04
(i,-67 V
KMRH
171' 25
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03
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1 87 24
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- 37 60
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50 4(1
126
66
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573 2L>
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61
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51 56
132
57
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191 74
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50 40
124
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577 75
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191
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36
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577
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191 74
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TV & FM Powrr Density
4f< 5'iHM
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36
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104 31
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90 1
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95 7
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83
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175
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1 87
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573
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61
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111 62
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KRMA
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179 75
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36 45
123 50
KU5A
191 74
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- 1 1 89
-7 63
36 45
135 82
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577 75
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37 67
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57
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KMPH
179
75
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39
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47
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133
94
KUbA
191
74
-23
79
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94
-P1
31
3ft
45
122
14
KDVN
577
75
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17
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Pl»
37
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119
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Total Powt'r Dphlt ty
P i) w p r
Pph >. i I y
( uW/( m\5)
01
01
------- |