United States
Environmental Protection
Agency
Air and Radiation
(NAREL)
400R-92-009
July 1082
Measurements of Electric
and Magnetic Fields in the
Waianae, Hawaii Area
EPA
40Q/R "-'if"
92-009'"!
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MEASUREMENTS OF ELECTRIC AND MAGNETIC FIELDS
IN THE WAIANAE, HAWAII AREA
JULY 1992
Edwin D. Mantiply
National Air and Radiation
Environmental Laboratory
1504 Avenue A
Montgomery, AL 36115-2601
U.S. Environmental Protection Agency
Office of Radiation Programs
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EXECUTIVE SUMMARY
During November 27-30, 1990, the U.S. Environmental Protection Agency
(EPA) conducted a measurement survey of electric and magnetic field levels along the
southwest coast of Oahu, Hawaii. These measurements were requested by the State
of Hawaii to determine the levels of radiofrequency (RF) electric and magnetic fields
near Navat radio transmitters at Luaiuatei. The objective was to determine maximum
fields in residential areas. This report documents the measurement results. Also, a
few measurements were made of extremely-low-frequency (ELF) electric and magnetic
fields at 60 hertz, the frequency used for eiectricai power.
Radiofrequency (RF) fields due to operation of the Lualualei Naval transmitters
were measured in three frequency bands: very-low-frequency (VLF), tow-frequency
(LF), and high-frequency (HF). Just outside the Navy site boundary, maximum
measured RF electric fields were 82, 0.5, and 8.8 volts/meter (V/m) in the VLF, LF,
and HF bands, respectively; maximum measured RF magnetic fields were 99, 0.9, and
22 miltiamps/meter (mA/m) in the same three bands. The VLF and LF transmitters
operate continuously and the HF transmitters operate intermittently. For the VLF
case, measurements were made near the boundary of the transmitter facility and
along the coastal highway as a means to bracket the likely range of fields in the area
in between. VLF fields ranged from 0.15 V/m to 82 V/m for the electric field and 2.5
to 99 rnA/m for the magnetic field. Because of the limited dynamic range of the
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equipment, the maximum LF field measured is probably somewhat less than the
actual maximum LF field outside the site boundary. The maximum measured level of
60 Hz ELF magnetic and electric fields in the Waianae area were 15 miiiigauss (mG)
and 30 V/m. ELF magnetic fields are generally reported in units of miiiigauss (mG)
while RF magnetic field are reported in units of milliamps per meter (mA/m). For
practical purposes 1 mG = 80 mA/m.
IV
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CONTENTS
Pag<
Preface vii
Acknowledgments ix
Figures xi
Tables xiii
1, Introduction 1
2. Equipment and Methods 3
2.1 VLF and LF Equipment and Methods 4
2,2 HF Equipment and Methods 8
2.3 ELF Equipment and Methods 8
3. Results and Discussion 10
3.1 RF Results 10
3.1.1 VLF Results 13
3.1.2 LF Results 22
3,1.3 HF Results 25
3.2 ELF Results 29
3.3 Discussion 33
4. Conclusions and Recommendations 34
References 35
Appendix: Calibration Data 36
v
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PREFACE
We believe the accuracy of the measurements made in this study is high because
of the appropriateness of the measurement approach and because the degree of
instrument uncertainty was low. Since the purpose of the study of electric and
magnetic fields at Lualualei was to determine the "maximum" fields to which an
individual could be exposed, a statistical sampling approach to measurement was
unnecessary. The relatively small area outside the Navy property and closest to the
antennas could be probed confidently with a field survey meter for the maximum
potential levels.
Moreover, the fact that the antennas under study generated fields that were
constant, that radiated equally in all directions, and that decreased in intensity with
distance allowed measurements sites to be selected with a great degree of freedom,
so long as objects that might perturb measurements (introduce shadows and
reflections) were avoided. Because these perturbations were avoided whenever
possible, we are confident "maximum" fields were measured. Finally, instrument
uncertainty, always a factor affecting the accuracy of field measurements, was within
ten percent of the measured values in this study.
VII
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ACKNOWLEDGMENTS
The support of transmitter operators and Navy specialists in field measurements
allowed the study to proceed smoothly. Arnold Den and Shelly Rosenblum of EPA
Region 9 provided field support. Toni West, an electrical engineering undergraduate
student employed at Environmental Protection Agency-Las Vegas, calibrated
instruments, corrected raw data, generated rough maps and plots, provided
background information in early drafts, and assembled the report, Richard Levy
contributed statistical analyses and the resultant graphics. EPA reviewers included
Shelly Rosenbium, Dr, Doreen Hill, Lynne Gillette, and Norbert Hankin, External peer
reviewers included Dr. Keith Florig, Research for the Future, Paul Gaiiey, Oak Ridge
National Laboratory, David Janes, Risk Analysis Corporation, Dr. Raymond Neutra,
State of California, and Richard Tell, Richard Tell Associates.
ix
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FIGURES
Number Page
1 Whip Antenna System 6
2 Study Area 11
3 Naval Radio Transmitter Facility at Lualuaiei 12
4 VLF Results 14
5 VLF Measurement Traversing Power Lines 19
6 VLF Electric Field Histogram and Smoothed Data 21
7 VLF Magnetic Field Histogram and Smoothed Data 21
8 LF Results 23
9 LF Electric Field Histogram and Smoothed Data 24
10 HF Resu ts Along Lualuaiei Homestead Road 27
11 Variation in Electric and Magnetic Fields in Front of Rhombic Antenna 28
12 HF Electric Field Histogram and Smoothed Data 29
13 HF Magnetic Field Histogram and Smoothed Data 29
14 ELF Results 30
15 ELF Electric Field Histogram and Smoothed Data 32
16 ELF Magnetic Field Histogram and Smoothed Data 32
XI
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TABLES
Number Page
1 Field Calibration of Whip Antenna System 7
2 VLF Results 15
3 VLF Measurements During Reduction of Power 20
4 LF Results 22
5 HF Results 25
6 ELF Results 31
7 Maximum Fields Measured During Study 34
XIII
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1, INTRODUCTION
At the request of the Hawaii Department of Health, the U. S. Environmental
Protection Agency (EPA) Office of Radiation Programs - Las Vegas Facility and EPA
Region 9 measured electric and magnetic fields in the Waianae area along the
southwest coast of Oahu. The Hawaii Department of Health and members of the
public were concerned that electric and magnetic fields generated by the nearby
Lualualei Naval Radio Transmission Facility might be relevant factors in a larger State
investigation of childhood cancer cases found in the area. Other environmental
agents, such as chemical contamination, are also being investigated by the Hawaii
Department of Health,
The electric and magnetic field sources of interest in this study were the radio
transmission antennas at the Lualuaiei Naval Radio Transmission Facility. The Naval
Facility operates high-power transmitters at 23.4 kilohertz (kHz) in the very-low-
frequency (VLF) range, at 146,1 kHz in the low-frequency (LF) range, and at various
frequencies in the high-frequency (HF) or shortwave range of 3 to 30 megahertz
(MHz), The VLF and LF transmitters operate continuously and the HF transmitters
operate intermittently.
This study was designed to determine fields in residential areas for the limited
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range of frequencies due to the operation of transmitters at the Lualualei Navai facility.
The results of measurements and the equipment and methods used in the study are
described in this report. Measurement instruments capable of determining electric and
magnetic fields in the frequency bands of VLF, LF, and HF were used. Several of the
instruments overlap more than one band.
In addition, some measurements of electric and magnetic fields at the extremeiy-
low-frequency (ELF) of 60 hertz were made to explore whether any unusual
circumstances existed with respect to power lines. Power lines operate at 60 cycles
per second or hertz (Hz) in the ELF frequency range, instruments capable of
measuring in the ELF frequency band were also used in this study.
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2. EQUIPMENT AND METHODS
The equipment used for electric and magnetic field measurements is matched to
the frequency of the field source under study. Each measurement device or system
has a frequency range over which it is calibrated and operates properly. These
instruments not only respond to fields over the specified frequency range but can afso
respond to fields outside this range. If the frequency cannot be determined with an
instrument (usually the case with survey meters), it can be difficult to determine the
source of the field causing the instrument response. For example, a radiofrequency
electric field survey meter will respond to strong ELF electric fields in addition to the
intended radiofrequency response. One approach to identifying the source of an
instrument response is to control the source presumed to cause the response. For
example, if the power of a transmitter is reduced and the meter reading drops
accordingly, then the transmitter being controlled is the cause of the instrument
response. In a case where the frequency can be determined with an instrument, the
field source can be. positively identified from the frequency if no other sources
operating on the same frequency are present. Both frequency readout and power
control approaches were used to identify field sources in this study. It should be
noted that all of the instruments used in this study were single-axis type; that is, only
the vector component of the field that is aligned with the instrument sensor or antenna
was determined. In atl cases the sensor axis was oriented to obtain a single maximal
response.
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2.1 VLF and LF Equipment and Methods
The same equipment was used to measure both VLF and LF fields. Electric
t
fields were measured with two Model EFS-1 meters manufactured by Instruments for
Industry and designed to operate over the frequency range of 10 kHz to 200 MHz.
These instruments were calibrated using a transverse electromagnetic (TEM) cell in
EPA's Montgomery laboratory [1]. Calibration data for the Instruments for Industry
meters are located in the Appendix. These instruments have certain limitations: they
measure only electric fields; do not measure frequency; may be susceptible to
interference from power line ELF electric fields; and have limited sensitivity. To
overcome some of these limitations, special measurement systems were assembled
and used as described below.
Magnetic fields were measured with an Eaton Model 94605-1, 5V4-inch loop
antenna connected to a Tektronix Model 212 battery-powered oscilloscope through a
50 ohm load resistor. The manufacturer's calibration curve for the SVWneh loop is
given in the Appendix. Correction factors for the loop and oscilloscope system were
determined with a TEM cell; these factors were used to convert oscilloscope readings
in millivolts peak-to-peak (mV p-p) to magnetic field in root-mean-square
mflliamps/meter (mA/m). The results of the TEM cell calibration are also shown on the
figure in the Appendix and are in good agreement with the manufacturer's curve. The
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magnetic fields were measured at locations away from any vehicles or other large
conducting objects, orienting the loop for maximum response, and reading the
oscilloscope for either the VLF or LF waveforms (see discussion below). The
polarization of the magnetic field was always horizontal, as expected, based on the
transmitting antenna geometry.
To measure electric fields and frequency, a standard magnetic mount whip
antenna about one meter long was attached to the top of a rental car and calibrated in
the field (see Figure 1). In this arrangement, the entire vehicle becomes part of an
electrically-small capacitive antenna system. The standard antenna cable was
replaced with a six-foot section of low capacitance cable (RG 62 A/U) to reduce
capacitive loading and increase sensitivity. This cable was connected to both the
oscilloscope and a Fluke Model 8060A digital voltage and frequency meter located
inside the vehicle. The system was calibrated in the field by approaching either the
VLF or LF transmitting antennas on the Navy site so that the field from either antenna
was dominant; reading the oscilloscope in the vehicle; and measuring the electric field
with both EFS-1 meters at the same location without the vehicle present. The
EFS-1 field readings (corrected and averaged) divided by the oscilloscope readings
become the calibration factor for the system. The VLF transmitter was shut down for
maintenance during the LF calibration. The VLF calibration was rechecked twice
during the study and the results are given in Table 1. The calibration factor did not
change significantly from VLF to LF frequencies. Proper readings with the whip
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Figure 1, Whip Antenna System
6
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system depend on the electric field being vertical and uniform near ground. For open
areas, this is a reasonable assumption for electric fields at VLF and LF frequencies
and is supported by the EFS-1 measurements, in processing the data, only the first
VLF calibration factor (10.19) was used, as it was obtained in a more open area.
TABLE 1. FIELD CALIBRATION OF WHIP ANTENNA SYSTEM
Calibration
Frequency
(kHz)
146,1
23.4
23.4
23,4
Averaged EFS-1
Field (V/m)
8.63
8.15
54.93
51.45
Oscilloscope Reading
(VP-P)
,84
.8
5.2
5.2
Factor
(V/mrms/Vp,p)
10.27
10.19
10.56
9,89
The whip system not only responds to VLF and LF electric fields generated by
the Navy transmitters, but also responds to 60 Hz ELF electric fields due to power
lines. The system could be used for ELF electric field measurements but was not
calibrated at 60 Hz for this study. The voltmeter reading is only useful when one
frequency is dominant; however, the oscilloscope display can be used to distinguish
the contribution from sources at different frequencies. The oscilloscope may display
up to three sinusoidal waveforms superimposed on top of each other. The fast LF
waveform "rides on top of the slower VLF waveform and the LF and VLF combined
are on top of the much slower ELF waveform, Careful triggering and reading of the
7
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oscilloscope allows the peak-to-peak voltage due to each of the waveforms to be
measured separately. An advantage of the whip system is that it allows continuous
i
observation of electric field variations while driving from one measurement location to
the next. This characteristic allowed us to observe and document any unusual field
variations between measurement sites.
2.2 HF Equipment and Methods
The HF electric field measurements were made using Instruments for Industry
EFS-1 survey meters. Magnetic fields at HF were measured using an Eaton Model
92200-3, 15-inch loop antenna connected to a Hewlett Packard Model 8482A power
sensor and Hewlett Packard Model 435B battery-operated radiofrequency power
meter. The manufacturer's calibration data for the 15-inch loop are included in the
Appendix, These data are used to derive an algorithm to convert power meter
readings to magnetic field strength in milliamps per meter (mA/m).
2.3 ELF Equipment and Methods
Two ELF survey meters were used in the study, A Monitor Industries Model
428-1 was used to measure 60 Hz magnetic fields and an Electric Field
Measurements Company Model 116 plus-2-60-2-300 was used to determine 60 Hz
8
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electric fields. Both instruments have been tested at EPA and are accurate to
ą 5 %. The objective of these measurements was to determine the upper limits of
fields due to power distribution lines in residential areas. Therefore, measurements
were made close to distribution lines but not made inside residences. Generally, a
single intersection in a neighborhood that had numerous overhead power distribution
lines was chosen. The area of the intersection was probed until a maximum reading
was found at any height from zero to two meters above ground.
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3. RESULTS AND DISCUSSION
Figure 2 shows the area of study along the southwest coast of Oahu, Hawaii,
from Makaha to Nanakuii. Sources of electric and magnetic fields include the radio
transmitters at the Lualualei Naval facility and overhead power lines.
3.1 RF Results
Radiofrequency (RF) electric and magnetic fields were measured at the VLF,
LF, and HF frequencies of Naval transmitters at Lualualei. Figure 3 shows details of
the Lualualei transmitter facility. Two towers at the south end of the facility support
the VLF transmitting antenna system operating continuously at a power of 512
kilowatts (kW) and a frequency of 23.4 kHz. Four towers nearby in a triangular
arrangement (one in the center) support the LF antenna system operating
continuously at a power of 50 kW and a frequency of 146.1 kHz. Many HF antennas
are located toward the northern end of the facility. These HF antennas can operate
intermittently at a variety of frequencies in the 3 to 30 MHz band at a maximum power
of 10 kW on any one antenna. The transmitter operating powers were confirmed by
maintaining communication with the operators of the Navy facility during the study
period. Also, a lower power Coast Guard transmitter operating at a medium-frequency
(MF) between 0.3 and 3 MHz exists at the eastern end of the site (not shown).
10
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Kaena
Point
Kahuku Point
Naval Radio
Transmitter Facility
(NRTF)
Barbers
Point
Makapuu
Point
Figure 2. Study Area
11
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^S22* %ad (ou\S^
0)
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The MF transmitter was not studied because the eastern boundary is not publicly
accessible.
3,1,1 VLF Results
VLF (23.4 kHz) electric and magnetic fields were studied much more
intensively than fields at other frequencies because of the high power of this
transmitter. Measurements were made along roads which were on the perimeter of
the Lualualei facility and along the coastal highway. The maximum off-site field
strengths should occur near the perimeter of the facility and the highway
measurements should include the minimum field strengths in the area studied.
Measurements were also made along Waianae Valley Road to the north of the site.
The results of these measurements are displayed on the map in Figure 4. Along the
perimeter roads electric fields varied from 0.15 to 61 V/m and magnetic fields varied
from 4.9 to 92 mA/m. Values of fields along the coastal highway were from 0.17 to
1.5 V/m for the electric field and 2.5 to 9.2 mA/m for the magnetic field. These
measurements were made using the 5!4-inch loop and whip antenna system with the
oscilloscope. Table 2 lists all of the VLF results, Note that the maximum VLF electric
field of 82 V/m was observed in an open area between residences south of iliili Road.
This value was found by searching the area for a maximum that was not perturbed by
vegetation or power lines.
13
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Pacific
Ocean
0.66 V/m
4,9 mA/m
0.41 V/m
2.5 mA/m
0.92 V/m
3.7 mA/m
0.45 V/m
2.5 mA/m
Naval Military
s// Reservation
0.41 V/m
3.7 mA/m
0.61 V/m
3.7 mA/m ___ ,
1.1 V/m
12 mA/m \
1.8 V/m
. 8.6 mA/m
1.2 V/m
t1 mA/m
0.61 V/m
^Itamwl-rtSS^Vi'v*
*o.7,wm >%f;,m12mA/m
0.15 V/m - V/m " mA/m
4.9 mA/m , v/m gj^
0.41 V/m
3.1 mA/m
0.61 V/m
6.2 mA/m
1.3 V/m
31 mA/
8.2 V/m
31 mA/m
APANA
TRAVERSE
0.61 V/m
6.2 mA/m
0.61 V/m
3.7 mA/m
0.17 V/m
4.9 mA/m
0.41 V/m
2 i mA/m
0.5
1.0 MILE
Died with permission, copyright J.R. Cte/e
0.51 V/m
2.5 mA/m
Figure 4. VLF Results
14
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TABLE 2. VLF RESULTS
DESCRIPTOR
Paakea Road from Road to
iliili Road
(measurements taken every 0,1 mile-
electric field only)
fliili Road from end to
Paakea Road
(measurements taken every 0,1 mite)
Mailiilil Road continuing on Lualualei
Homestead Road from Paakea Road to Fence Road
(measurements taken every 0,2 mile)
ELECTRIC MAGNETIC
FIELD (V/m) FIELD (mA/m)
.61
1.5
1.7
3.5
1
5.1
5,1
6.1
5,6
5,1
12
15
15
12
16
18
12
15
12
51
56 62
61 86
51 77
39 71
20 68
2 31
.15 4.9
,71 7.4
.71 11
,71 15
,61 12
continued on next page
15
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TABLE 2 - Continued
DESCRIPTOR
Kaukama Road from Paakea Road to end
(measurements taken every 0.2 mile)
Farrington Highway from Makaha Vailey Road to
Kahe Power Plant
(measurements taken every 0,5-0.7 mile)
ELECTRIC
FIELD (V/m)
2.2
1.5
1,2
1,1
1.7
1.8
.61
14
9.7
1.7
5.1
.41
.45
.36
.41
.61
1
1
1.5
1,5
1
,61
1
1.1
.61
.17
.41
.51
MAGNETIC
FIELD (mA/m)
11
12
11
12
11
8.6
6.2
92
57
40
9.2
2.5
2.5
3.7
3,1
3,7
4.9
9.2
8
6.8
6.2
6,2
6,2
5.5
3.7
4.9
2.5
2.5
continued on next page
16
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TABLE 2 - Continued
DESCRIPTOR
Waianae Valley Road and Haieahi Road Intersection
0.55 mile west from Haieahi Road on Waianae
Valley Road
Punanaula Street and Kaneaki Street
0.55 mile west from Kaneaki on Waianae Valley Road
Momona Place and Waianae Valley Road Intersection
Dead end of Hakimo Road
going toward Paakea Road
(measurements taken every 0,1 mile)
ILIILI TRAVERSE
0.2 miles from end of Iliili Road
going into field perpendicular to Iliili Rd,
(not shown on map)
{measurements taken every 20 meters)
APANA TRAVERSE
Paakea Road and Apana Road Intersection
going parallel to Apana Road
(measurements taken every 5 meters)
(not shown on map)
ELECTRIC
FIELD (V/m)
,66
,41
,92
,41
,61
1.3
8.2
11
7,7
8,1
3,1
24
64
72
75
75
72
63
57
60
52
47
45
24
14
26
33
MAGNETIC
FIELD(mA/m)
4,9
3.7
3.7
3,7
3.7
31
31
31
25
22
15
74
74
74
68
68
77
62
62
62
55
49
49
92
92
99
80
continued on next page
17
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TABLE 2 -- Continued
ELECTRIC MAGNETIC
DESCRIPTOR FIELD (V/m) FIELD(mA/m)
42
44
52
measurements taken every 10 meters) 52
51
47
47
44
48
40
74
74
74
68
62
62
60
62
62
62
In field off I ni: Road' 82
On iliili Road" 50
45
Farrington Highway near
Manununu Street' .66
' Comparison points (see Table 4).
As it became apparent during the study that overhead power lines shielded or
reduced VLF electric fields beneath the lines, measurements were taken on the
opposite side of the road from power lines whenever possible. To characterize this
effect and establish maximum field values, two sets of measurements were made
along traverses running perpendicular to power lines immediately outside the southern
and western boundary fences of the transmitter facility {see Figures 3 and 4), Results
of these traverse measurements are given in Figure 5. Both magnetic and electric
fields were measured using hand-held instruments: the 5%-tnch loop and oscilloscope
18
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APANA TRAVERSE
o
o
CO
4= c
O O)
0> OS
ui 5
100
90
0 10 20 30 40 50 60 70 80 90 100 110m
Distance from Power Line (meters)
ILIILI TRAVERSE
20
i I
0 10 20
i i i i
40 60 80 100 120 140 160 180 200m
Distance from Power Line (meters)
Figure 5, VLF Measurement Traversing Power Lines
19
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and an EFS-1 meter. In the upper plot, "APANA TRAVERSE," power lines are at both
0 and 10 meters; in the lower plot there was only one power line at 0 meters, ft was
found that VLF electric fields beyond the power lines in an open area could be 4 times
greater than fields directly beneath the lines. This implies that other VLF electric field
measurements made under power lines may be 4 times less than electric fields in
adjacent open areas. It is known that houses also shield VLF electric fields reducing
fields inside residences (see reference [2]). The VLF magnetic field was not as
strongly affected by the power lines as was the electric field.
To identify the source of field readings more clearly, the Navy, in cooperation with
EPA, reduced the VLF transmitter power to 50 percent its normal value at scheduled
times. The consistent drop in instrument field strength reading observed at these
times in Table 3 confirmed that the source of the field was the VLF antenna. Note
that field strength is proportional to the square root of the source power, so that a 0.5
reduction in power implies a 0.707 reduction in field.
TABLE 3. VLF MEASUREMENTS DURING REDUCTION OF POWER
Measurement
System
Location Field Strength Field Strength Ratio
at Normal Power at Half Power
IF! EFS-1
In Field Off
Iliili Road
Whip and Digital On fiiili Road
Voltmeter
82 V/m
50 V/m
53 V/m
35 V/m
.65
.7
continued on n&xt page
20
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TABLE 3 -- Continued
Measurement
System
Whip and
Oscilloscope
Whip and
Oscilloscope
Location Field Strength Field Strength
at Normal Power at Half Power
Ratio
On Iliili Road
45 V/m
Farrington Highway 0.66 V/m
Near Manununu
Street
31 V/m
.49 V/m
0.69
.74
Histograms and smoothed data distribution plots for the VLF data are shown in
Figures 6 and 7, The distributions are bimodal, which reflects two measurement
populations: those at relatively low levels far away from the Navy site and a separate
population of measurements at higher levels close to the site (see Section 3.2 ELF
Results for explanation of plots).
02S -
Q2Q-
0.16 -
0,10 -
0.05 -
il
-1.0 -0.2 o.e 1,4
tog E(V/m)
S2
Figure 6, VLF Electric Field Histogram
and Smoothed Data
0,3 -i
r\
1.8
ao
log
Figure 7. VLF Magnetic Field
Histogram and Smoothed Data
21
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3.1.2 LF Results
Low-frequency fields were relatively weak and difficult to detect. The LF
(146.1 kHz) waveform could be observed superimposed on the top of the oscilloscopi
VLF waveform only when the LF response was greater than about one tenth the VLF
response. A value is only reported for LF electric and magnetic fields where the LF
response could be clearly read. The results are listed in Table 4 and shown on the
map in Figure 8. Measured LF electric fields varied from 0.05 to 0.5 V/m. LF
magnetic fields were measured at only two sites; both readings were 0.9 mA/m.
TABLE 4. LF RESULTS
ELECTRIC MAGNETIC
DESCRIPTOR FIELD (V/m) FIELD (mA/m)
Punanauia Street and Kaneaki Street ,2
Lualualei Homestead Road from Mailiilii Road .5
going east .5
(measurements taken every 0.2 mile) .5
.5 .9
.9
Farrington Highway .1
starting at Makaha Valley Road going south .05
(measurements taken every 0.5 mile) .1
Three values at north end and three values ,1
at south end of Farrington Highway .1
.1
22
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Pacific
Ocean
Naval Military
Reservation
0.5
1.0 MILE
Viad with permission, copyflgM J.R. Clam
Figure 8. LF Results
23
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The limited measurement data presented here do not allow an accurate estimate
of the maximum LF field strength at the site boundary. However, these results are
compatible with a maximum LF electric field value at the site boundary of 1,24 V/m
reported by the Navy in 1982 [3],
A histogram and smoothed data distribution p!ot for the LF electric data are
shown in Figure 9. No histogram is possible for the magnetic field data, since there
were only two sites and both had the same reading.
0.5 -
0,4 -
CŁ
to
Ł 03-
Q
1 0.2 -
8
^ 0.1 -
x^X"
---ť
X
-1.0 -0.8 -0.8 -0.4 -0,2 0.0
log E(V/m)
Figure 9. LF Electric Field Histogram and
Smoothed Data
24
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3,1.3 HF Results
The large number of HF (3 to 30 MHz) antennas and possible operating
frequencies precluded a study of all HF operating conditions. To estimate maximum
field strengths outside the Luaiualei facility due to HF operations, tests were performed
near two antennas close to the northern boundary of the site. Measurements were
made along Luaiualei Homestead Road near a rhombic type antenna operating at
8.077 MHz and near an inverted cone type antenna operating at 13.523 MHz, These
antennas were operated in coordination with the Navy at the maximum of 10 kW of
power and at typical operating frequencies. The results are listed in Table 5 and
shown in Figure 10, The maximum magnetic field measured was 22 mA/m and the
maximum electric field measured was 8.8 V/m. These were due to operation of the
inverted cone antenna.
TABLES, HF
DESCRIPTOR
Luaiualei Homestead Road
going east along road
starting from center of rhombic mainbeam
(measurements taken every 5 meters)
RESULTS
ELECTRIC
FIELD (V/m)
1,9
1.7
1.5
1.8
2,3
2.7
MAGNETIC
FIELD (mA/m)
6.2
6.4
7
6.6
5.9
5.9
continued on next page
25
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TABLE 5 -
DESCRIPTOR
Lualualei Homestead Road
in front of inverted cone antenna
Puhawai Road and Luaiualei Homestead
Continued
ELECTRIC
FIELD (V/m)
2.7
3.2
3.2
2.7
2.5
2.2
2
1.9
2
2
7.1
8.8
MAGNETIC
FIELD (mA/m)
6.4
6.6
6.6
6.4
6.1
5.8
5.4
5.2
4.8
4.4
20
22
The plot in Figure 11 shows the variation in electric and magnetic fields in front
of the rhombic antenna. As expected, electric fields near ground are at a maximum at
locations somewhat off the main beam axis [4]. Histograms and smoothed data
distribution plots for the HF data are shown in Figures 12 and 13. The distribution is
bimodal because data from measurements near the inverted cone and rhombic
antennas have been combined.
26
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2.Q V/m 4.4 mA/m
1,9 V/m S.2 mA/m
2 V/m 5.8 mA/rn
V/m 6,4 mA/m
2 V/m 6.6 rnA/rn
V/m 5.9 mA/m
a V/m 6,6 mA/m
2.O V/m 4.8 mA/m
2.0 V/m S.4 mA/m
2.5 V/rn 6.1 mA/m
3.2 V/m 6.6 mA/m
2.7 V/m 6.4 mA/m
2,3 V/m 5.9 mA/m
1.5 V/m 7.O mA/m
1.9 V/m 6.2 mA/m
7.1 V/rn
2O mA/m
a.e v/m
22 mA/m
Figure 10. HF results along Luaiuaiei Homestead Rd.
27
-------
ii
0 D>
0) CC
UJ 2
0
0 10 20 30 40 50 60 70 80 m
Distance along Luaiualei Homestead Road (meters)
Figure 11. Variation in Electric and Magnetic Fields In Front oi Rhombic Antenna
28
-------
0,4 Q8
lag ESV/m)
1.2
Figure 12. HF Electric Field Histogram
and Smoothed Data
0,6 -i
0.4-
0.2 -
OB OB 1.0 1,2 1.4 1,9
tog H(mA/m)
Figure 13, HF Magnetic Field
Histogram and Smoothed
3.2 ELF Results
ELF electric and magnetic fields were measured at residential street
intersections that had numerous power distribution lines. Eleven measurement sites
were selected (Fig. 3). Generally, each intersection was probed for a maximum field
reading. In some measurements were made at different corners of an
intersection or at the middle of a block. Measurements taken in this way should
sample the upper limits of fields due to power distribution lines in residential areas.
The map in Figure 14 and the list in Table 6 show the results. ELF electric field
strength values varied from 3.4 to 30 volts/meter (V/m) and magnetic field flux density
varied from 0.5 to 15 milligauss (mG) or 40 to 1200 miiamps/meter (mA/m).
29
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Pacific
Ocean
Naval
Reservation
0.5
1.0 MILE
Used with permission, copyright J,R, Clare
Figure 14, ELF Results
30
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TABLES. ELF
INTERSECTION
Farrington Highway and Nanakapona
School
Auyong Homestead Road and Holomaiia
Street
Hakimo Road at end of pavement
Hakimo Road and Paakea Road
0.2 miles from end of iliili Road
Hookele Street and Ehu Street
Maliona Street and Farrington Highway
Kulaaupuni Street and Maliona Street
Mill Street and Luaiualei Homestead Road
Mill Street and McArthur Street
Farrington Highway and Kaupuni Street
RESULTS
ELECTRIC MAGNETIC
FIELD (V/m) FIELD (mG)
17 10
30 ,8
3.4 .5
21 4.8
8.5 1
4 4
5,2 2,5
14 1.7
18 5
25 1.3
4.1 15
Histograms and smoothed data distribution plots for the ELF data are shown in
Figures 15 and 16, In order to avoid highly skewed distributions, the logarithm base
10 of each data value in Table 6 has been calculated before entering the data into a
statistical distribution plotting program. In addition, the units for the magnetic field
31
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have been converted from miliigauss to miltiamps per meter by multiplying by 80
before taking the logarithm. Interpreting these distributions is illustrated as follows,
The histogram bar plot for the ELF electric field shows that most of the log of
measurement values fall between 1.2 and 1.4 or, by taking the antilog (10*), most of
the values fall between 15.8 and 25.1 volts per meter. The proportion per bar for this
bar is about 0,37, meaning that 37% of the maximum electric field values measured at
selected intersections are between 15.8 and 25.1 V/m. As another example, the
smoothed distribution plot for the ELF magnetic field shows a peak in the log of the
magnetic field distribution at about 2.2 or, taking the antilog, at 158 milliamps per
meter or 2.0 milligauss. Thus, the most probable maximum magnetic field measured
in selected residential intersections is 2.0 mG.
0,4 -
cc
1 0.3 -
uj
5 05-
g 0,1 -
Q_
X
..
0,4 0,8
.^
i
\
\
1,2 1.6
log ECV/m)
ffi
,| 0,4-
S 0.3 -
§ 0.2 -
8 0.1 -
CL
Q
^.
s \.
7^ \
\
\,
°- 1,5 2,5 3.5 45
og H(mA/m)
Figure 15. ELF Electric Field
Histogram and Smoothed Data
Figure 16. ELF Magnetic Field
Histogram and Smoothed Data
32
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3.3 Discussion
This report presents results from a measurement survey intended to identify
maximum electric and magnetic field levels in residential areas near Naval radio
transmitters at Luaiualei. The object was to gain some understanding of field levels in
the community rather than conduct a exposure assessment. The survey is
thus considered exploratory for that reason, as well as for the following considerations,
The equipment used was portable and somewhat limited. Measurement sites were
not chosen on statistical or epidemiologies! considerations, but, rather, were
chosen based on engineering judgment-the primary objective being to find the
maximum field in publicly accessible out of doors. Finally, even though almost
all the measurements were made in residential areas (housing, although sparse,
surrounds the Navy site where readings were taken along roads and traversing power
lines) the sites chosen for each frequency band are at different locations, which could
result In misleading comparisons between data sets for the different bands.
Only in the VLF band are the measurement data adequate to infer a range of
field strength in the area. However, the VLF data do not allow prediction of exposure
at any particular location. If this information were required, the next logical step would
be to define numerical models of the VLF tower system and compare the results of
numerical electromagnetic computer calculations to the measurement data. A
confirmed model could then be used for field prediction.
33
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4, CONCLUSIONS AND RECOMMENDATIONS
This report documents the results of magnetic and electric field measurements
made during the last week of November 1990 in the Waianae area of Oahu, Hawaii.
The maximum electric and magnetic fields measured outside of the Navy site
boundary in each frequency band are shown in Table 7. The range of VLF fields
measured was 0.15 to 82 V/m and 2,5 to 99 mA/m. The lower levels of fields at ELF,
LF, and HF can not be inferred from the measurement data.
TABLE 7. MAXIMUM FIELDS MEASURED DURING STUDY
Frequency
ELF
VLF
LF
HF
Electric
Field (V/m)
30
82
.5
8.8
Magnetic
Field (mA/m)
1200 (15 mG)
99
.9
22
If further efforts to quantify exposures in the area are directed, several activities
could be initiated. These could include computer modeling of field sources,
modulation measurements, ELF exposure measurements using generally accepted
protocols, long-term monitoring of HF exposures, measurements of contact currents,
and measurements indoors. However, such efforts could be expensive and may add
only a marginal amount of additional information on field levels in the Luaiualei area.
34
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REFERENCES
1. Mantiply, Edwin D. An Automated TEM Cell Calibration System, U.S.
Environmental Protection Agency, EPA 520/1-84-024, October 1984.
2, Smith, A.A., "Attenuation of Electric and Magnetic Fields by Buildings," IEEE
Transaction on Electromagentic Compatibility, EMG-20(3), August 1978.
3, Personnel Radhaz (Radiation Hazard) Measurements at RTF Luatualei; Final
Report. Department of the Navy, Naval Communication Area Master Station,
Eastern Pacific, Wahiawa, Hawaii 96786-3050, October 1982.
4. Mantiply, Edwin D., Hankin, Norbert N. Radiofrequency Radiation Survey in the
McFarland, California Area. U.S. Environmental Protection Agency, EPA/520/6-
89/022, September 1989.
35
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APPENDIX
CALIBRATION DATA
36
-------
1,042
.984
.890
,880
.988
.952
.870
.860
1.046
.980
.865
.859
.964
.909
.825
.825
IF! EFS-1 1059-E
CorrectionFactors
Full Scale (V/m)
Frequency (MHz) 3,00 10.0 30.0 .100
.0234
.1461
8.077
13.523
IFl EFS-1 1060-E
Correction Factors
Full Scale (V/m)
Frequency (MHz) 3.00 JJXQ 30.0 100
.0234
.1461
8.077
13.523
1.087
,992
.909
.887
1.067
.988
.909
.889
1.082
.969
.887
.865
1.039
.952
.860
.860
37
-------
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100 250
Frequency In Kilohertz
9 measured conversion factors found in TEM ceil
Conversion Factors for Picotesla Terns
Model 94605-1 LOOD Antenna
38
-------
S3
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36
32
I6.C 17,0 iŤ,0 19.0 21,0 22,0 23J3 24,0 25.O 26.G 27,0 28.O 29,0 3O,0 31,0 32.0
(,-*^ FREQUENCY-MC/S
CALIBRATED BYl ' K , FOR SES 92200-3 LOOP ANTENNA
S /
DATE:
SERIAL NO.
acs ivx-toot CHART 4- CORRECTION FACTORS, REMOTE LOOP ANTENNA
NOTES: Ž antenna factors used for HF measurements
39
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