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National Institute of Standards and Technology

NISTIR 90-3938

MEASUREMENT OF

ELECTRIC FIELD STRENGTH

NEAR HIGHER POWERED

PERSONAL TRANSCEIVERS

John Adams

Doris Wu

Alan Budlong

-QC

100

.056

90-3938

1990
NATIONAL INSimrrE OF STANDARDS &

TECHNOLOGY

Research Information O^te:

Gaithersburg, MD 2(®99

DATE DUE

Demco, Inc. 38-293
NISTIR 90-3938

MEASUREMENT OF

ELECTRIC FIELD STRENGTH

NEAR HIGHER POWERED

PERSONAL TRANSCEIVERS

John Adams

Doris Wu

Alan Budlong

Electromagnetic Fields Division

Center for Electronics and Electrical Engineering

National Engineering Laboratory

National Institute of Standards and Technology

Boulder, Colorado 80303-3328

May 1 990

Sponsored by

Law Enforcement Standards Laboratory

National Institute of Standards and Technology

Gaithersburg, Maryland 20899

U.S. DEPARTMENT OF COMMERCE, Robert A. Mosbacher, Secretary

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, John W. Lyons, Director
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CONTENTS

Page

1 INTRODUCTION 1

2 FIELD STRENGTH MEASUREMENTS 2

2.1 Energy Sources 2

2.2 Instrumentation 2

2.3 Test Facilities 3

3 MEASURED DATA 5

4 COMPARISON OF MEASURED DATA WITH THE ANSI C95. 1-1982

STANDARD AND CONCLUSIONS 6

5 REFERENCES 7
LIST OF FIGURES

Figure Page

1 Non-metallic support structure for array of 10 probes 8

2 Complete support structure used in anechoic chamber 9

3 Rotation of personal transceivers 10

4 Illustration of method of keying transceiver using pneumatic

bubble and hand pump 11

5 Setup for measurements on ground screen 12

6 Picture of setup for measurements inside anechoic chamber 13

7 Picture of setup for measurements on ground screen. Note

black plastic cover over probe array to block sunlight 14

8 Display of magnitude and x, y and z components of the electric

field distribution of probe #4 (figure 8a)

,

probe #6 (figure 8b)

,

and probe #8 (figure 8c), all at a distance of 12 cm from

transceiver R823 15

9 Plot of electric field around transceiver F40 (40 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 16

10 Plot of electric field around transceiver F40 (40 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes

are shown as a function of angle of rotation 17

11 Plot of electric field around transceiver D40 (40 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes

are shown as a function of angle of rotation 18

12 Plot of electric field around transceiver D40 (40 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 19

13 Plot of electric field around transceiver E162 (162 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 20

14 Plot of electric field around transceiver E162 (162 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 21

15 Plot of electric field around transceiver D162 (162 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 22

IV
LIST OF FIGURES (contd.)

Figure Page

16 Plot of electric field around transceiver D162 (162 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 23

17 Plot of electric field around transceiver C464 (464 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation. Effects of

discharging and recharging battery may be seen 24

18 Plot of electric field around transceiver C464 (464 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation. Effects of

discharging and recharging battery may be seen 25

19 Plot of electric field around transceiver B464 (464 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 26

20 Plot of electric field around transceiver B464 (464 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 27

21 Plot of electric field around transceiver A823 (823 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 28

22 Plot of electric field around transceiver A823 (823 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation 29

23 Plot of electric field around transceiver B823 (823 MHz) at a

separation distance of 7 cm. Fields detected by 9 probes are

shown as a function of angle of rotation. Effects of

discharging and recharging battery may be seen 30

24 Plot of electric field around transceiver B823 (823 MHz) at a

separation distance of 12 cm. Fields detected by 9 probes are

shown as a function of angle of rotation. Effects of

discharging and recharging battery m.ay be seen 31

25 Three-dimensional plot of magnitude of electric field around

transceiver F40 (40 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

.

Maximum value of field strength is marked with black dot. The

two numbers after MAXIMUM POINT are electric field strength involts per meter and angle of rotation in degrees 32

V
LIST OF FIGURES (contd.)

Figure Page

26 Three-dimensional plot of magnitude of electric field around

transceiver F40 (40 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot. The

two numbers after MAXIMUM POINT are electric field strength in

volts per meter and angle of rotation in degrees 33

27 Three-dimensional plot of magnitude of electric field around

transceiver D40 (40 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

.

Maximum value of field strength is marked with black dot. The

two numbers after MAXIMUM POINT are electric field strength in

volts per meter and angle of rotation in degrees 34

28 Three-dimensional plot of magnitude of electric field around

transceiver D40 (40 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot. The

two numbers after MAXIMUM POINT are electric field strength in

volts per meter and angle of rotation in degrees 35

29 Three-dimensional plot of magnitude of electric field around

transceiver E162 (162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

.

Maximum value of field strength is marked with black dot. The

two numbers after MAXIMUM POINT are electric field strength in

volts per meter and angle of rotation in degrees 36

30

Three-dimensional plot of magnitude of electric field around

transceiver E162 (162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 37

31

Three-dimensional plot of magnitude of electric field around

transceiver D162 (162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 38
LIST OF FIGURES (contd.)

Figure Page

32 Three-dimensional plot of magnitude of electric field around

transceiver D162 (162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 39

33 Three-dimensional plot of magnitude of electric field around

transceiver C464 (464 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 40

34 Three-dimensional plot of magnitude of electric field around

transceiver 0464 (464 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field

strength in volts per meter and angle of rotation in degrees 41

35 Three-dimensional plot of magnitude of electric field around

transceiver 0464 (464 MHz) measured on ground screen -- compare

with figure 28 which was measured in anechoic chamber. Radii of

disks are proportional to magnitude of electric field.

Separation distance between transceiver antenna and probes

is in centimeters (RADIUS = 12) . Maximum value of field

strength is marked with black dot. The two numbers after

MAXIMUM POINT are electric field strength in volts per meter

and angle of rotation in degrees 42

36 Three-dimensional plot of magnitude of electric field around

transceiver B464 (464 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS == 7).

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 43

37 Three-dimensional plot of magnitude of electric field around

transceiver B464 (464 MHz). Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

,

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 44

vii
LIST OF FIGURES (contd.)

Figure Page

38 Three-dimensional plot of magnitude of electric field around

transceiver A823 (823 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7).

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 45

39 Three-dimensional plot of magnitude of electric field around

transceiver A823 (823 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 46

40 Three-dimensional plot of magnitude of electric field around

transceiver B823 (823 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7).

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 47

41 Three-dimensional plot of magnitude of electric field around

transceiver B823 (823 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

.

Maximum value of field strength is marked with black dot.

The two numbers after MAXIMUM POINT are electric field strength

in volts per meter and angle of rotation in degrees 48

42 Comparison of maximum measured values of electric field strength

with limit from ANSI C95. 1-1982, Safety Levels with Respect to

Human Exposure to Radio Frequency Electromagnetic Fields 49

43 Comparison of the square of E field (proportional to power density)

calculated from maximum measured values of electric field strength

with limit from ANSI C95. 1-1982, Safety Levels with Respect to

Human Exposure to Radio Frequency Electromagnetic Fields 50

Vlll
Measurement of Electric Field Strength

Near Higher Powered Personal Transceivers

John Adams, Doris Wu, and Allen Budlong

Electric field strengths were measured at a number of points

near 5-W personal transceivers. The points were located on

cylinders of revolution around the antenna with radii of 7,

9.5, 12, 14.5, 17, and, in some cases, 27, 37, and 47 cm. At

shorter distances, these measured values exceeded the

exposure limits suggested in ANSI Standard C95. 1-1982.

Key words: electric field measurements; personal

transceivers; walkie-talkies.

1 . INTRODUCTION

Law enforcement and other public safety personnel use various types

of communication equipment in the performance of their day-to-day

activities. Since the inception of Federal funding in the early 1970s, many

law enforcement agencies have substantially increased the number of handheld

personal transceivers used in their departments. A decade ago, most of

these radios generated between 1 and 2 W of output power. In the past few

years, however, many agencies are purchasing transceivers that produce as

much as 5 or 6 W of output power as a means of improving communication range

and system reliability. Unfortunately, a by-product of this enhanced

capability is an increase of field strengths in the vicinity of the

transceiver and its antenna.

Because of concern regarding the electromagnetic environment in

which law enforcement personnel must work, the Technology Assessment Program

Advisory Council recommended the initiation of a study to characterize this

environment at the frequency bands used by police. The first phase of the

measurement program produced a report on field strengths in vehicles with

communications transmitters [1]. This effort was primarily directed toward

measuring the fields produced by mobile transceivers used in vehicles. The

1
second phase of this effort, reported in this document, is concerned with

the field strengths produced by higher powered, handheld transceivers. This

report contains the results of tests conducted on typical transceivers in

the four frequency bands used by the law enforcement community: 30-50, 150-

174, 400-520, and 806-866 MHz. The fields were measured at distances likely

to be encountered in practice.

2. FIELD STRENGTH MEASUREMENTS

2 . 1 Energy Sources

During this measurement series, personal transceivers were used that

operated at frequencies of 40.27, 162.475, 464 and 823 MHz and with

approximate output powers of 5, 5, 5, and 3 W, respectively. Electric field

strengths were measured at locations described by cylinders of increasing

radii with the antenna of the transceiver at the center of the cylinder.

2.2 Instrtunentation

The electric field strength was measured with the multisensor,

automated electric field strength measurement system described in NBSIR 86-

3056 [2]. This multisensor system consists of 10 probes. Each probe has

three dipoles; each dipole feeds a single channel which can be used to

measure the x, y, or z components of the electric field. RF energy is

converted to dc voltage by a diode detector at each dipole. Data from each

channel were then stored in a file using a computer system and the software

described in NBSIR 86-3056 [2]

.

The data were then converted into volts per

meter with a calibration factor correction applied for each specific

frequency. The x, y, and z components of the electric field for each probe

II I 2 ^ 2 and also the magnitude, |E|= JE +E +E , were recorded in units of

volts per meter vs degrees of rotation of the transceiver.

A support structure shown in figure 1 held the probes in a vertical

array with a separation of 10 cm between each probe. The support structure

was built of nonmetallic material so as to minimize reflections. Probe #1

was at the bottom of the array while probe #10 was at the top. The complete

support structure is shown in figure 2.

2
The probe array could be repositioned horizontally to change

separation distance. It could also be repositioned vertically by 5 cm to

increase the number of measurement points from 10 to 20. The vertical

position is indicated by the term "offset" in some figures. Vertical

adjustment was also used to obtain a common reference point for each of the

personal transceivers. This reference point was determined by placing the

base of the antenna on the transceiver at the same height as the probe #5.

All the personal transceivers had different antenna lengths and body

dimensions

.

The measurements were made with the probe array held stationary at

one of several separation distances while the personal transceiver was

rotated in increments as shown in figure 3. Rotation was in a clockwise

direction as seen from above with the 0“ point on the short side of the

transceiver case toward the probe array. The size of the rotation increment

was a compromise between stepping speed and battery discharge rate.

In order to key the transceiver on, a pneumatic switch was

improvised as shown in figure 4. It consisted of a rubber bulb taped and

strapped to the push- to -talk switch. This switch was linked by a length of

plastic tube to a hand-operated air pump. As the pump was actuated, the air

bubble attached to the personal transceiver expanded, and turned on the

transmitter. The personal transceivers were never left on for more than 45

seconds, since there was a noticeable decrease in the electric field as the

battery discharged and the output stage heated. After each rotation of 360°

the transceiver batteries were recharged so that each rotation had the same

battery charge as the previous one.

2.3 Test Facilities

The measurements were made using either of two facilities depending

on the frequency of the transceiver. For transceivers operating at 464 and

823 MHz, measurements were made in an anechoic chamber. The measurements

were fully automated, since the chamber is equipped with a five -axis

positioner that allowed rotation of the personal transceiver 360° in 3.6° or

7.2° steps as shown in figure 3. This allowed for 100 or 50 data points,

respectively. The personal transceiver was supported above the rotator by a

long fiberglass tube. The top of the tube had a wooden platform to support

3
the personal transceiver while the bottom was attached to the rotator. The

wooden table was covered with anechoic material to reduce reflections. The

probe structure was also supported by a wooden table.

Horizontal separation distances of 7 , 9.5, 12, 14.5, 17, 27, 37, 47,

57 cm were used. The smaller increments at smaller separation distances

were necessary to show the more rapid spatial variations in field strengths

close to the transceiver. However, at the 7 and 9.5 cm distances, the side

of the transceiver case would hit the array of probes between approximately

135° and 225° of rotation, so no values could be recorded within those

limits (See figure 3)

.

For transceivers operating at 40.27 or 162.475 MHz, measurements

were made on an outdoor ground screen, since the absorber in the anechoic

room is not effective at these lower frequencies. The measurements on the

ground screen were not automated and therefore took more time; only 16 steps

of rotation could be used before the battery charge was reduced below an

acceptable level. All the rotations were done by hand in 22.5° steps as

shown in figure 5. The rotation was accomplished by rotating a fiberglass

support tube from a tunnel under the ground screen. An additional tube was

attached to the support tube to allow this rotation and to indicate the

azimuth

.

Because the probes were sensitive to sunlight, the probe fixture had

to be wrapped in black plastic. The probes were not affected by moderate

changes in temperature. At the lower frequencies fewer increments of

separation distance were used, and offsets in elevation were also omitted

since the spatial variations in field strength are not as rapid at the

longer wavelengths. Figure 6 is a photograph of the setup in the anechoic

chamber. Figure 7 is a photograph of the setup on the groundscreen.

The probes were calibrated and have an uncertainty of ±1 dB in field

strength. All values reported have this as a basic uncertainty. The values

measured on the ground screen, where the positioning uncertainty was ±1 cm,

have the same basic uncertainty, but the values may not have been measured

at exactly the position reported. At 40 MHz, this causes an additional ±4

dB uncertainty; at 162 MHz, an additional ±3 dB uncertainty. Positioning

4
errors in the anechoic chamber were very small, less than ±1 mm; this causes

an additional ±0.25 dB uncertainty.

An operator's hand and arm may cause increase of field strengths

during actual use of a transceiver over those measured when the transceiver

was supported by a plastic structure. This is due to the increase in

effective size of ground screen for the monopole antenna of the transceiver.

This effect was about +3 to +4 dB in limited cases, but was not thoroughly

investigated.

3 . MEASURED DATA

For each of the transceivers measured in the anechoic chamber, 25500

data points were recorded, and from these, 8500 data points for the

magnitude of E were calculated. Only 336 data points were recorded for a

transceiver measured on the ground plane.

All measured values of the x, y, and z components of the electric

field are available, along with calculated values of magnitude, on a DOSformatted disk if anyone should want to calculate coupled energy based on

boundary conditions. Figures 8a, 8b, and 8c illustrate this depth of detail

of information. is the vertical component of electric field.

The magnitude of the E field is the quantity used in the next set of

figures, 9-24. The data are displayed in two-dimensional plots for each

transceiver at the shortest separation, 7 cm, and at a distance of 12 cm,

the shortest distance which allowed a full 360° rotation of the transceiver.

The horizontal axis is the angle of rotation. The 7 cm separation shows

maximum field strengths. Some problems that occurred during data gathering

(such as variation due to varying battery voltage) show up in some of these

figures. Vertical displacement is indicated by the term offset.

Figures 25 through 41 are three-dimensional plots in cylindrical

coordinates; they show the spatial variations in field strength around the

antenna of the transceiver. The radii of the disks are proportional to

measured field strengths; the highest field strengths occur in the volume

immediately adjacent to the transceiver antenna. There are no nulls or low

field strengths in the immediate vicinity of the transceiver antenna.

5
4 . COMPARISON OF MEASURED DATA WITH THE ANSI C95. 1-1982 STANDARD AND

CONCLUSIONS

It is not within the scope of this study to state what levels of

electromagnetic fields constitute a health hazard. Such issues are outside

the mission and expertise of the National Institute of Standards and

Technology (NIST) and are the responsibility of organizations and committees

that have been established to perform and interpret research on the

biological effects of electromagnetic fields and to set exposure limits

based on the results of such research. NIST is responsible for the accurate

measurement of electromagnetic fields.

The American National Standards Institute (ANSI) , together with the

Institute of Electrical and Electronic Engineers (IEEE) and the US

Department of the Navy, have prepared and adopted a voluntary radio

frequency protection guide for the frequency bands involved in this

measurement program. This guide was published as ANSI C95. 1-1982, Safety

Levels with Respect to Human Exposure to Radio Frequency Electromagnetic

Fields, 300 kHz to 100 GHz [3]. It was reviewed and approved by the 35

organizations and government agencies listed on page 4 in the standard.

This ANSI standard gives limits in units of field strength squared

2 2 (V/m) for electric field strength, (A/m) for magnetic field strength), and

2 mW/cm for power density as a function of frequency. These limits were

selected to keep the specific absorption rate (SAR) below 0.40 W/kg of human

tissue as averaged over the whole body and the SAR below 8 W/kg averaged

over any 1 g of tissue. Values are given in table 1 and shown graphically

in Figure Al of the standard.

The presentation format that is probably of most interest to the

user of these transceivers is a graph of typical measured field strengths

plotted relative to the field strength limit for human exposure to radiofrequency fields as given in the ANSI C95. 1-1982 Standard [3]. There are

many temporal and spatial variations allowed by this standard, but these

measured data show that the field strengths are clearly greater than the

2 recommended levels. At 40 and 162 MHz, E is about two orders of magnitude

greater than the value specified in this standard. See figures 42 and 43.

6
Although the measured values of field strength from these transceivers are

high relative to the exposure limits of the ANSI standard, how much energy

couples into the body is not really known. What is needed is a more thorough

analysis of the coupling of electromagnetic energy into a phantom of a human

head, with particular emphasis on coupling into the eyes, which are usually very

near the strongest fields measured, near the antenna of the transceiver. The

eyes are one of the more vulnerable organs of the human body because the poor

capacity of the circulatory system within the eyes is inefficient at removing

heat

.

5 . REFERENCES

[1] J.F. Shafer, Field Strength Levels in Vehicles Resulting from

Communication Transmitters, NIJ Report 200-83, National Institute of

Justice, U.S. Department of Justice, Washington, DC 20531, June 1984.

[2] W.D. Bensema, G.H. Koepke , and H.W. Medley, Handbook for Operation and

Maintenance of an NBS Multisensor Automated EM Field Measurement System,

NBSIR 86-3056, Oct. 1986.

[3] Safety Levels with Respect to Human Exposure to Radio Frequency

Electromagnetic Fields, 300 kHz to 100 GHz, American National Standards

Institute, ANSI C95. 1-1982.

7
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12

Figure

5.

Setup

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measurements

on

ground

screen.
Figure 6. Picture of setup for measurements inside anechoic chamber.

13
Figure 7. Picture of setup for aeasurements on ground screen. Note black

plastic cover over probe array to block sunli^t.

14
Radius= 12 Offset= 0

Radius^ 12 Offset^ 0

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X

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Radius= 12 OffGel= 0

Figure 8. Display of magnitude and x, y and z components of the electric

field distribution of probe #4 (figure 8a), probe #6 (figure 8b),

and probe #8 (figure 8c), all at a distance of 12 centimeters from

transceiver R823.

15
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transceiver

F40

(40

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at

separation

distance

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Fields

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9

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transceiver

F40

(40

MHz)

at

separation

distance

of

12

cm.

Fields

detected

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9

probes

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electric

field

around

transceiver

D40

(40

MHz)

at

separation

distance

of

7

cm.

Fields

detected

by

9

probes

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Figure

14.

Plot

of

electric

field

around

transceiver

E162

(162

MHz)

at

separation

distance

of

12

cm.

Fields

detected

by

9

probes

a

shown

as

a

function

of

angle

of

rotation.
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Figure

16.

Plot

of

electric

field

around

transceiver

D162

(162

MHz)

at

separation

distance

of

12

cm.

Fields

detected

by

'

probes

a

shown

as

a

function

of

angle

of

rotation.
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Radius=

7

Offset

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26

Figure

19.

Plot

of

electric

field

around

transceiver

B464

(464

MHz)

at

separation

distance

of

7

cm.

Fields

detected

By

9

probes

a

shown

as

a

function

of

angle

of

rotation.
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27

Figure

20.

Plot

of

electric

field

around

transceiver

B464

(464

MHz)

at

separation

distance

of

12

cm.

Fields

detected

by

9

probes

a

shown

as

a

function

of

angle

of

rotation.
A823

Radius=

7

Offset

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28

Figure

21.

Plot

of

electric

field

around

transceiver

A823

(823

MHz)

at

separation

distance

of

7

cm.

Fields

detected

by

9

probes

a

shovm

as

a

function

of

angle

of

rotation.
Radius^

1

2

Offset

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29

Figure

22.

Plot

of

electric

field

around

transceiver

A823

(823

Milz)

at

separation

distance

of

12

cm.

Fields

detected

by

9

probes

a

shown

as

a

function

of

angle

of

rotation.
Radius=

7

Offset

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(uj/a) Piai; 3

30

Figure

23.

Plot

of

electric

field

around

transceiver

B823

(823,

MHz)

at

a

separation

distance

of

7

cm.

Fields

detected

by

9

probes

are

shown

as

a

function

of

angle

of

rotation.

Effects

of

discharging

and

recharging

battery

may

be

seen.
Radius=

12

Offset

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31
7

P40

RADIUS - NUMBER or POINTS - 16

0- MAXIMUM POINT: 720.30 -112.50

Figure 25. Three-dimensional plot of magnitude of electric field around

transceiver F40 (40 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

32
RO

RfiDlUS - 12

NUMBER or POINTS - 16

MAXIMUM POINT: 426.43 180.00

Figure 26. Three-dimensional plot of magnitude of electric field around

transceiver F40 (40 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS .= 12)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

33
D40

RADIUS - 7

NUMBER or POINTS - 16

M- MAXIMUM POINT; 309.60 -112.50

StuL of electric field.

_ Separation distance between

transceiver antenna and probes is

J;" ^ two

Maximum value of field strength is marked

i^^volts

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

34
35
E162

RADIUS - 7

NUMBER or POINTS -

= MAXIMUM POINT:

16

566.61 112.50

Figure 29. Three-dimensional

transceiver E162

plot of magnitude of electric field around

(162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

36
E162

RfiDlUS - 12

NUMBER or POINTS - 16

0- MAXIMUM POINT: 193.38 157.50

Figure 30 Three-dimensional plot of magnitude of electric field around

transceiver E162 (162 MHz). Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS — 12)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees

37
D162

RADIUS - 7

NUMBER or POINTS - 16

0- MAXIMUM POINT: 880.30 -112.50

Figure 31. Three-dimensional plot of magnitude of electric field around

transceiver D162 (162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

38
D162

RADIUS - 12

NUMBER or POINTS - 16

MAXIMUM POINT: 266.10 157.50

Figure 32. Three-dimensional plot of magnitude of electric field around

transceiver D162 (162 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS =* 12)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.
C464

RADIUS - 7

NUMBER or POINTS - 100

MAXIMUM POINT: 297.11 104.40

I

I

I

I

I

I

I

I

Figure 33. Three-dimensional plot of magnitude of electric field around

transceiver C464 (464 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 7)

Maximum value of field strength is marked with black dot. The two

numbers al^ter MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

40
C464

RRDIUS - 12

NUMBER or POINTS - 50

MAXIMUM POINT: 179.84 144.00

Figure 34. Three-dimensional plot of magnitude of electric field around

transceiver C464 (464 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS - 12)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per' meter and angle of rotation in degrees

41
C464G

RADIUS - 12

NUMBER or POINTS - 16

0- MAXIMUM POINT: H8.53 -157.50

Figure 35. Three-dimensional plot of magnitude of electric field around

transceiver C464 (464 MHz) measured on ground screen -- compare

with figure 28 which was measured in anechoic chamber. Radii of

disks are proportional to magnitude of electric field. Separation

distance between transceiver antenna and probes is in centimeters

(RADIUS = 12)

Maximum value of field strength is marked with

black dot. The two numbers after MAXIMUM POINT are electric field

strength in volts per meter and angle of rotation in degrees.

42
B464

RfiDlUS - 7

MUnBER OF POINTS - 100

0- MRXIMUM POINT: 158.82 10^.40

Fieure 36 Three-dimensional plot of magnitude of electric field aroundFigure 3b Radii of disks are proportional to

Stude of electric field. Separation distance between

trfnsceiver antenna and probes is in centimeters (^DIUS -

7)^

Maximum value of field strength is marked

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees

43
B464

RADIUS “ 12

NUMBER OF POINTS - 0- MAXIMUM POINT:

50

82.22 151.20

Figure 37. Three-dimensional plot of magnitude of electric field around

transceiver B464 (464 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS “ 12)

Maximum value of fiefd strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

44
R823

RfiDIUS - 7

NUMBER or POINTS -

‘ MAXIMUM POINT:

100

88.96 -108.00

Figure 38. Three-dimensional plot of magnitude of electric field around

transceiver A823 (823 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS “ 7).

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees

45
R823

RRDIUS - 12

NUMBER or POINTS - 50

MAXIMUM POINT: 56.70 158.^0

c "T

»

Figure 39. Three-dimensional plot of magnitude of electric field around

transceiver A823 (823 MHz) . Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS = 12)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

46
B823

RADIUS - 7

NUMBER or POINTS - 100

MAXIMUM POINT: 157.69 - 28.80

Figure 40. Three-dimensional plot of magnitude of electric field around

transceiver B823 (823 MHz). Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS == 7).

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

47
B823

RfiDIUS - 12

NUMBER or POINTS - 50

#- MAXIMUM POINT: 95.00 72.00

I

<±>

Figure 41. Three-dimensional plot of magnitude of electric field around

transceiver B823 (823 MHz). Radii of disks are proportional to

magnitude of electric field. Separation distance between

transceiver antenna and probes is in centimeters (RADIUS 12)

Maximum value of field strength is marked with black dot. The two

numbers after MAXIMUM POINT are electric field strength in volts

per meter and angle of rotation in degrees.

48
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Figure

42.

Comparison

of

maximum

measured

values

of

electric

field

strength

with

limit

from

ANSI

C95.

1-1982,

Safety

Levels

with

Respect

to

Human

Exposure

to

Radio

Frequency

Electromagnetic

Fields.
Measured

vs

ANSI

Limit

ANSI

C95.1-1982

Std

for

Human

Exposure

to

RF

Fields

00

o

o

o

oo

o

o

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u.S. GOVERNMENT PRINTING OFFICE: 1990 - 776-344/25150

Figure

43.

Comparison

of

the

square

of

E

field

(proportional

to

power

density)

calculated

from

maximum

measured

values

of

electric

field

strength

with

limit

from

ANSI

C95.

1-1982,

Safety

Levels

with

Respect

to

Human

Exposure

to

Radio

Frequency

Electromagnetic

Fields
BL-114A

(5-90)

U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

BIBLIOGRAPHIC DATA SHEET

PUBLICATION OR REPORT NUMBER

NISTIR 90-3938

2. PERFORMING ORGANIZATION REPORT NUMBER

3. PUBUCATION DATE

May 1990

4. TITLE AND SUBTITLE

Measurement of Electric Field Strength Near Higher Powered Personal Transceivers

5. AUTHOR(S)

John Adams, Doris Wu, and Alan Budlong

6. PERFORMING ORGANIZATION (IF JOINT OR OTHER THAN NIST, SEE INSTRUCTIONS)

U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

BOULDER, COLORADO 80303-3326

7. CONTRACT/GRANT NUMBER

8. TYPE OF REPORT AND PERIOD COVERED

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (STREET, CITY, STATE, ZIP)

Law Enforcement Standards Laboratory

National Institute of Standards and Technology

Gaithersburg, Maryland 20899

10. SUPPLEMENTARY NOTES

11. ABSTRACT (A 200-WORD OR LESS FACTUAL SUMMARY OF MOST SIGNIFICANT INFORMATION. IF DOCUMENT INCLUDES A SIGNIFICANT BIBUOGRAPHY OR

UTERATURE SURVEY, MENTION IT HERE.)

Electric field strengths were measured at a number of points near 5-W personal transceivers.

The points were located on cylinders of revolution around the antenna with radii of 7, 9.5,

12, 14.5, 17, and, in some cases, 27, 37, and 47 cm. At shorter distances, these measured

values exceeded the exposure limits suggested in ANSI Standard C95. 1-1982.

12. KEY WORDS (6 TO 12 ENTRIES; ALPHABETICAL ORDER; CAPITAUZE ONLY PROPER NAMES; AND SEPARATE KEY WORDS BY SEMICOLONS)

electric field measurements; personal transceivers; walkie-talkies

13. AVAILABIUTY

UNUMITED

FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE TO NATIONAL TECHNICAL INFORMATION SERVICE (NTIS).

X

X

ORDER FROM SUPERINTENDENT OF DOCUMENTS, U.S. GOVERNMENT PRINTING OFFICE,

WASHINGTON, DC 20402. ORDER FROM NATIONAL TECHNICAL INFORMATION SERVICE (NTIS), SPRINGFIELD, VA 22161.

14. NUMBER OF PRINTED PAGES

60

IS. PRICE

ELECTRONIC FORM
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