Radiation Effect_Cellular BTS and Handsets

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The Sixth International Conference on Advanced Science and Technology Exchange with Thailand,

Bangkok, Thailand, July 17-19, 1996 CELLULAR TRANSMITTER TOWERS AND HAND-HELD

TELEPHONES: ARE THEY HAZARDOUS?

Artnarong Thansandote*, Ph.D., Gregory Gajda and David Lecuyer

Radiation Protection Bureau, Health Canada

775 Brookfield Road, Postal Locator 6301B, Ottawa, Ontario K1A 1C1

*E-mail: [email protected]

Abstract -- In this paper, a summary of biological effects and Canadian exposure standards for

RF fields is presented. Typical exposure levels in the vicinity of cell-site antennas as well as RFenergy absorption in the human head during the use of cellular telephones are discussed. Part

of the presentation covers an overview of Health Canada's activities in this area and the

assessment of health risks from exposure to RF fields from cellular transmitter towers and

hand-held telephones.

I. INTRODUCTION

Since the introduction of analog radiotelephone systems in the mid 1980's, cellular

telephones have rapidly gained popularity and have become one of the fastest selling consumer

electronic products. It has been estimated that the number of North Americans using cellular

telephones has increased from about 100,000 in 1984 to over 10 million in 1992 [1]. Whilecellular communications technology has been rapidly advancing, cellular telephone users have

become increasingly concerned about the potential harmful effects of radiofrequency (RF) fields

from these devices. Concerns have also been voiced by members of the general public who live

close to cellular base station towers and roof-top antennas. In recent years, public awareness

of exposure to RF fields have been reflected in the media and have resulted in increased

scientific research.

In Canada, cellular telephones receive radio transmissions from a central base station or cell-

site at frequencies between 869 and 894 megahertz and transmit radio signals back to the cell-

site at frequencies between 824 and 850 megahertz [2]. Portable, hand-held cellular telephones

have a maximum output power of 0.6 watts (W). In some models, the antenna may be used ineither extended or retracted position.

The base station consists an array of cellular antennas, radio transmitters and receivers, and

electronic switching equipment necessary for connecting the mobile telephones within the cell

to the rest of the telephone network. Connection to the outside network is usually made

through a microwave radio link utilizing a dish antenna. Base station cellular antennas are

usually co-linear arrays of about 4 m in overall length or planar or flat-plate arrays. They are

mounted either on a freestanding tower (43 -122 m high) or on the roof of a building. In a

given cell, the number of available channels depends on the frequency reuse scheme and may

number over 100.



1 10 1 0 10 10 10 10 10 10 10 10 10 10

3 x1 0 3x10 3x10 3x10 3 x1 0 3x1030 0.38 6 5 4 3 2 - 2 -3 -47

Frequen cy (H z)

Wavelength (m)

FM & TV BroadcastTowers

CellPhones

AM Radios Ovens

Power

Distribution

Energy (eV)10 10- 12 - 1 0 - 8 - 6 - 4 - 2

VLF LF M F HF VHF UH F SHF

Microwave

2

II. OBJECTIVES

Following the highly publicized personal lawsuit against cellular telephone companies in

Florida in 1992 and recent public opposition to the siting of base stations in residential areas,

scientists at Health Canada have conducted research to address the health issues related to the

RF emissions from hand-held cellular telephones and base station transmitters. This researchinvolves the experimental evaluation of RF energy absorption in the human head during the use

of cellular telephones as well as the measurement of RF fields in the vicinity of a typical urban

cellular tower. These measurements have been carried out along with a continued monitoring

of the scientific developments in the biological effects of RF fields. The purpose of this paper

is as follows:

1. To present a brief overview of the biological effects of RF fields and the exposure limits in

Safety Code 6 [3] as applied to the use of cellular telephones.

2. To report the results of the measurements and discuss how they compare with the published

data and the exposure limits specified in Safety Code 6.

III. RADIOFREQUENCY ELECTROMAGNETIC FIELDS

Electromagnetic radiation can be characterized as waves of electric and magnetic fields that

are produced by the movement of electrical charges in a source such as a cellular antenna. As

the wave propagates through space, the electric and magnetic fields oscillate. The distance that

a wave travels in one cycle of oscillation is referred to as the wavelength which is measured in

metres (m). The number of times these fields oscillate per second past a given point is called

frequency which is expressed in cycles per second or hertz (Hz). In free space, electromagnetic

waves travel at the velocity of light which is 3 x 10 metres per second (m/s). Waves with low8

frequencies have long wavelengths and waves with high frequencies have shorter wavelengths.

Figure 1. Radiofrequency part of the electromagnetic spectrum and some typical applications.



3

Frequencies and wavelengths for the RF part of the electromagnetic spectrum are illustrated

in Figure 1. Cellular radio operates in the 800-900 megahertz (800-900 million Hz) band. This

frequency band is higher than those of AM, FM and TV but lower than that of radars and

microwave ovens.

The electric field is measured in units of volts per metre (V/m), while the magnetic field isin amperes per metre (A/m). The rate of transmission of RF energy, referred to as the power

density, is measured in watts per square metre (W/m ). The power density is defined as the rate2

of energy flow (W) through a given surface area, divided by the area (m ).2

Describing the RF field in terms of power density is appropriate when the point of interest

is in the so-called "far-field" region, located at very large distances from the source. In this

region, the RF field has the characteristics of a plane-wave, i.e. the electric and magnetic field

strengths are uniform about a plane which lies normal to the direction of propagation. In the

far-field, there exist simple physical relationships between the magnitudes of power density and

the strengths of electric and magnetic fields [3], [4].

No such simple relationship applies when the point of interest is very close to the source

as in the "near-field" region. The distances involved are comparable to the wavelength of the

radiated RF energy and the fields possess components related to the storage as well as the

propagation of energy.

In the case of human exposure to RF fields from a cellular transmitter tower, the exposed

person is located in the far-field region. Under this condition, a person's entire body is subject

to exposure and standard dosimetry estimations (whole body) can be applied.

Hand-held telephones are somewhat different in that only part of the body is exposed at

very close range to the source. The presence of the head in the near-field interacts with thesource i.e. the antenna and handset. This in turn, affects the rate and pattern of energy

deposition in the tissues. Because of the strong interdependence between source characteristics

and body in the near-field region, exposures are not easily defined and predictions of energy

deposition based on plane-wave dosimetry estimations are highly inaccurate. In the case of

hand-held cellular phones, the determination of energy deposition must be made by either

modelling the situation with mathematical techniques or by direct measurement on so-called

"phantoms" exposed with actual cellular telephone handsets [5]-[7].

IV. BIOLOGICAL CONSIDERATIONS

Biological responses and effects due to exposure to RF fields are related to the amount of

RF energy absorbed in the body [8]. The absorption and distribution of RF energy depends

strongly on the frequency, intensity and orientation of the incident fields as well as the body

size. It has been shown that RF absorption in the body, for plane wave exposure, approaches

a maximum value when the long axis of the body is parallel to the electric field, and has a length



4

equal to four-tenths of a wavelength. At frequencies above 1 MHz, the amount of energy

absorption is commonly described in terms of the specific absorption rate (SAR). This is a

measure of the rate of energy deposition per unit mass of body tissue and is usually expressed

in units of watts per kilogram (W/kg).

During the past three decades, a wide variety of biological effects and responses attributedto exposure to RF fields (including microwaves) have been reported and reviewed extensively

[8], [9]. The significant effects based on laboratory and human studies may be summarized as

follows:

Laboratory Studies

1. Exposure to sufficiently high intensity RF fields can result in elevation of tissue or body

temperature. Biological effects due to induced heating that results in a temperature rise of

greater than 1 C have been established. Most responses have been reported at a SAR o

above approximately 1-2 W/kg.

2. A few reports have been documented on chromosomal or DNA changes in animals due to

low intensity RF exposures. The level of exposure was not sufficient to cause a significant

increase in body temperature. The mutagenic effects could not be replicated by independent

researchers.

3. Overwhelmingly, experimental data indicate that RF fields are not mutagenic, and so are

unlikely to act as cancer initiators.

4. In two recent studies with rodents, there is the suggestion that RF fields may affect DNA

directly. The responses were observed at SARs of about 1.2 W/kg (2.45 GHz continuous

wave fields) or 0.6 W/kg (2.45 GHz pulsed fields). These studies have yet to be replicated before the findings can be used in any health risk assessment.

5. There is limited information on the effects of long-term, low-level exposures. Exposure of

100 rats for most of their lifetime to 0.4 W/kg did not show any effect on tumour incidence.

So far, there is no data to support any long-term biological effects that are due to exposures

below thermally significant levels.

6. The threshold power density for cataract formation in the rabbit eye from exposure to 2.45

GHz microwaves for at least 1 h is about 1.5 kW/m . Repeated exposures (23 h/day for 2

180 days) at a level of 100 W/m did not cause any changes in rabbit eyes. Cataracts were2

not observed in monkeys exposed to 1.5 kW/m for over 3 months.2

7. In vitro studies have shown enhanced cell transformation at 4.4 W/kg followed by treatment

with a chemical promoter.



5

8. Biological responses to amplitude-modulated RF fields or microwaves have been reported

at SARs too low to cause heating. Effects have been found within both modulation

frequency windows and power density windows. Some of these responses have been

difficult to confirm, and their physiological consequences are not clear.

Human Studies

1. There are a few studies that address human populations exposure to RF fields. The

majority of reports concern personnel exposed in military or industrial settings.

2. Epidemiological studies have failed to show significant association between RF exposures

and adverse health effects.

3. In studies with human volunteers, thresholds for noticeable warming have been reported

at 270 - 2000 W/m (2 -10 GHz range), depending on the body area irradiated and the2

duration of exposure.

4. People with normal hearing can perceive individual pulses of RF fields at frequencies

between about 200 MHz and 6.5 GHz. The perception has been described as audible

clicks, chirping or buzzing sounds, depending on pulse characteristics. The perception

threshold for pulses of less than 30 µs has been estimated as about 400 mJ/m at 2.45 GHz,2

corresponding to peak specific energy in the head of about 16 mJ/kg.

V. CANADIAN GUIDELINES FOR LIMITING EXPOSURE

Health Canada's guidelines for limiting exposure to RF fields in the frequency range 10 kHz

to 300 GHz have been published as Safety Code 6 and are used for the instruction and guidance

of personnel employed in federal government agencies and those who are under the jurisdictionof the Canada Labour Code. Safety Code 6 contains exposure limits for both RF workers and

the general public. It has become a de facto national standard as applied to broadcasting and

radio communications through the regulations imposed by Industry Canada. Before a license

for the installation, modification or operation of any radio transmitter is issued by Industry

Canada, the owner must prove that it will operate within the recommended guidelines of this

safety code. Although there is no legal obligation, the provinces have adopted the federal

recommendations outlined in Safety Code 6.

The recommended exposure limits are based on a review of experimental evidence of

detectable biological effects [10]. The limits specified in this code have been set much lower

than thresholds where potential harmful effects begin. An RF exposure level of 4 W/kg has

been judged by scientific consensus as a threshold of potential harm. Maximum exposure levels

for RF workers are set such that limits of RF absorption do not exceed 0.4 W/kg, as averaged

over the whole body mass. For non-RF workers, including the general population, an

additional safety factor was incorporated to arrive at a basic limit of 0.08 W/kg, as averaged



6

over the whole body mass.

Table 1. Canadian Field Strength Exposure Limits for Non-RF Workers

(f is the frequency in MHz).

Frequency Strength; rms Strength; rms Density

(MHz) (V/m) (A/m) (W/m )

Electric Field Magnetic Field Power

2

0.01 - 1 280 2.19 -

1 - 10 280/ f 2.19/ f -

10 - 30 28 2.19/ f -

30 - 300 28 0.073 2

300 - 1,500 1.616 f 0.004 f f/1500.5 0.5

1,500 - 300,000 62 0.16 10

Because SAR is difficult to measure in the working environment, the "surrogate"

parameters of electric and magnetic field strength or power density are used for practical

application of the limits. The values of field strength and power density that correspond to

the 0.08 W/kg limit are shown in Table 1. For a cellular transmitter frequency of 885 MHz,

the power density exposure limit is 5.9 W/m . In general, the exposure limits specified in2

Safety Code 6 are comparable to other national and international standards.

For portable radio transmitters such as hand-held cellular telephones, an estimate of

exposure should be made directly in terms of the SAR. According to Safety Code 6, the

field strengths produced by such devices may exceed the limits in Table 1, provided the

following SAR values are not exceeded:

- The SAR averaged over any 0.2 of the body mass 0.2 W/kg

- The local SAR in the eye 0.2 W/kg

- The local SAR averaged over any 1 g of tissue,

except the body surface and the limbs 4 W/kg

- The local SAR at the body surface and in the limbs

(averaged over any 10 g of tissue) 12 W/kg



7

VI. TYPICAL EXPOSURE LEVELS FROM CELLULAR TRANSMITTERS

In this Section, maximum exposure levels in the vicinity of typical base stations and peak

SAR data for typical hand-held telephones are reviewed and compared with the Safety Code

6 limits.

Fixed Base Stations

Because of their radiation characteristics, exposure of the public at ground level, to the

main beams of the antennas, should not be possible at very close distances. At these distances,

the exposure is likely from the side lobes where power levels are at most 15 dB (32 times)

below that of the main beam.

RF fields in the vicinity of typical transmitter towers of these systems have been measured

and the published data are summarized in Table 2 [2]. The ground-level maximal power

density per radio channel was found to be 100 µW/m . For a system with a maximum of 962

channels, the combined maximum power density which the general public could possibly beexposed to is less than 0.01 W/m . This worse-case-scenario exposure level is 600 times below2

the limit specified in Safety Code 6 (5.79 - 5.96 W/m in the frequency range 869 - 894 MHz).2

RF fields from base stations with antennas mounted on the roofs of tall buildings have also

been measured. In some cases, the antennas are mounted such that the bottom of their

radiating portion is at head height of an individual standing on the roof. Even so, it has been

found that human exposure to near field power densities greater than 1 W/m is unlikely [2].2

Digital cellular systems which employ Time Division Multiple Access (TDMA) schemes share

the same RF spectrum as the analog ones. A future digital communication system which will

soon be implemented in Canada is known as Personal Communication Network (PCN). A

similar system, known as DCS1800, which has been used in Europe operates with 20 W of

power per channel within a band of frequencies spread around 1.8 GHz. At a distance of 58

m from the DCS1800 base station, calculated maximum electric field and magnetic field are 27

V/m and 0.07 A/m, respectively [11].



8

Table 2. Typical Ground-Level Maximum Exposure from Transmitter Towers [2].

Antenna Height Maximal Measured Power Distance from the Tower

(m) Density per Radio Channel Base

(µW/m ) (m)2

46 80 26

51 100* 12

66 35 65

82 80 60

*500 µW/m at a location close to the metallic fence, about 10 m from the base.2

Table 3. Peak SAR Levels in the Head for 0.6-W Hand-Held Units (825 - 845 MHz),

averaged over 1g of Tissue.

SAR Level Evaluation Method Reference

(W/kg)

0.45 Measurement Balzano et al., 1984 [12]

0.7 Measurement Joyner et al., 1992 [13]

0.16 - 0.69 Calculation Gandhi, 1995 [14]

2.82 Calculation Dimbylow and Mann, 1994 [5]

0.12 - 0.83 Measurement Anderson and Joyner, 1995 [7]

1.2 - 2.28 Calculation Jensen and Rahmat-Samii, 1995 [15]

0.2 - 1.6 Measurement Balzano et al., 1995 [16]

1

2

3

Data in good agreement with measurement.1

Numerical modelling at 900 MHz.2

Numerical modelling at 915 MHz.3

Hand-Held Telephones

RF energy deposition in the head during the normal use of hand-held cellular telephones has

been investigated. Numerical modelling and measurement data of peak SARs in phantom heads

for 0.6 W hand-held units are summarized in Table 3. The data indicate that, between 800 and

915 MHz, local SARs are less than the 4 W/kg limit specified in Safety Code 6. The effects

of body proximity and a hand holding the phone have been investigated and found to increase

the measurement by 4 - 17% (Anderson and Joyner, 1995). The SARs induced in the eye of



9

a phantom head exposed to a number of telephones were found to be in the range from 0.007 -

0.21 W/kg, depending on the conditions of use. This is considered not to exceed the Safety

Code 6 limit.

VII. HEALTH CANADA MEASUREMENTS

Hand-Held Telephones

At Health Canada, a vigorous research program into SAR measurements in phantoms and

exposure measurements from towers, has begun. The SAR measurements make use of an

electromechanical positioning system which scans an isotropic electric field probe inside the

head of a half-torso, human-equivalent phantom. The fibreglass shell of the phantom is filled

with a liquid which has identical electrical properties to human brain. The miniature implantable

probe is scanned under the control of a computer which acquires the data and processes it to

calculate SAR. The results can be either stored for further processing or displayed to show

SAR distributions. A contour plot of the SAR distribution from a typical "flip" style phone is

shown in Fig.2. It corresponds to a scan plane of about 20 cm from the bottom of the fibreglassshell, oriented on it's side as in the figure.

The distribution in Fig.2 illustrates that the maximum SAR is located roughly in the ear

region of the head where the handset is closest. A vertical scan of the SAR, beginning at the

bottom of the shell and moving away from the phone is shown in Fig.3. It shows a maximum

SAR of approximately 1.8 W/kg at the point nearest the phone. This value is within the Safety

Code 6 limits especially when averaged over a 1 g mass (a cube with approximately 9 mm

sides).

Several phones operating in the 800-900 MHz cellular band have been evaluated so far. In

all cases, the distribution of SAR indicates that most of the energy is deposited superficially andthat measured peak SARs have been under the Safety Code 6 limits given previously. One

interesting outcome has been that peak SARs are higher when phones with retractable antennae

are operated with the antenna in the retracted position.



480 500 520 540 560 580 600 620 640 660 680

60

80

100

120

140

160

180

200

220

10

Fig. 2. Contour plot of SAR distribution in human equivalent phantom. Scan level: 20 cm.

Phone type: "flip" style.



11

Fig. 3. SAR versus vertical height of probe at x-y position where distribution is maximum.

Cellular Radio Transmitter Towers

Cellular towers present a challenging field measurement situation in that a large number

of channels may be simultaneously present with dramatic differences in amplitude from channelto channel and with channels going "on" and "off" the air at random times. A broadband

radiation hazard meter based on an isotropic electric field probe with square-law detection

would be ideal in principle, however they are typically designed for much higher power

densities than those encountered near cellular towers and do not have sufficient sensitivity.

Instead, a probe antenna and portable spectrum analyzer with data logging capability were used

because of the sensitivity and dynamic range inherent to spectrum analyzers.

The cellular tower under investigation was located in a low density urban area next to a

major road. The free standing structure was approximately 40 m tall with six identical wedge-

shaped antennae arrayed around the top and a parabolic dish mounted 5 meters below.

The probe antenna was a half-wave, folded dipole approximately 16 cm long and tuned to

the middle of the cellular band (800-900 MHz). The probe was mounted on a linen phenolic

tripod about 1.2 m above the ground. Typical locations for the probe were on the sides of roads

or in parking lots. At each measurement location the spectrum analyzer acquired all the active



12

channel frequencies for a period of 5 minutes. After establishing frequencies, it continuously

scanned the entire band for a period of 6 minutes (as per the time-averaging requirements in

Safety Code 6), averaging the power density received in each channel. At the end of the

averaging period the total power density was summed over all the channels.

Five different locations were chosen for measurements, ranging from 15 m to 525 m fromthe base of the tower. The number of active channels ranged from 93 to 116 for the different

locations and maximum power densities for a single channel ranged from 1.28 µW/m to 76.72

µW/m . The table below gives the number of channels acquired and the total power density for 2

each of the different measurement locations.

Table 4. Number of channels acquired and total power density

(time averaged over 0.1 h) for each of the different measurement locations.

Distance From Tower Number of Channels Total Power Density

(m) Acquired (µW/m )2

15 96 9.5

25 93 81

130 98 460

340 91 136

525 116 497

From the table it can be seen that total power density actually increased with distance from

the tower. This may be partly due to the antenna pattern of the radiators and partly to multi- path effects, since no attempt was made to adjust the probe antenna for peak response. In all

cases, the total power density of all the channels is well within the Safety Code 6 limit of 5.9

W/m . This fact was evident from the beginning when one considers that the measurements2

could not have been made with a standard radiation hazard meter because of lack of sensitivity.

VIII. CONCLUSIONS

While the cellular phone and personal communications services industry expands their

coverage, they continue to face public opposition in the siting and installation of transmission

facilities. This opposition is mainly due to a perception of health risks from exposure to RF

fields from the roof-top and tower antennas.

In terms of measured or calculated exposures, a person experiences a much higher energy

deposition rate from the use of a hand-held cellular phone than from standing directly below

a cellular base station tower. In the former case, deposition rates have been measured or



13

modelled to be typically lower than Canadian and international standards, while in the latter

case rates are many orders of magnitude below. It should be remembered, however, that the

determination of SARs for the phones is based on simple physical (phantoms) or mathematical

models and cannot yet be measured directly on humans. Thus more work is needed in order to

refine the models in order to arrive at more definitive answers.

Not withstanding the fact that the general public's resistance to the presence of

transmission facilities is due to their perception of health implications from these devices, it

appears that public health concerns need to be addressed. A comprehensive communication

package should be available for dissemination.

ACKNOWLEDGMENT

The authors are grateful to Mr. Oscar Garay of Motorola, Inc., for his assistance in the set-up

of the RF dosimetry measurement system. Thanks are extended to Messrs. Todd Eakins,

Philippe Bisaillon and Patrick Shooner as well as Ms. Margaret Cheng for their conscientious

help in the SAR measurement for a number of cellular radiotelephones.

REFERENCES

[1] M. Fischetti, "The cellular phone scare," IEEE Spectrum, vol. 30, pp. 43-47, June 1993.

[2] R.C. Petersen and P.A. Testagrossa, "Radio-frequency electromagnetic fields associated

with cellular-radio cell-site antennas," Bioelectromagnetics, vol. 13, pp. 527-542, 1992.

[3] Health and Welfare Canada, Limits of Exposure to Radiofrequency Fields at Frequencies

from 10 kHz - 300 GHz: Safety Code 6 . Canada Communication Group -Publishing,

Ottawa, Ontario K1A 0S9, Canada, Catalogue No. H46-2/90-160E, 1991.

[4] National Council on Radiation Protection and Measurements, NCRP Report No. 19: A Practical Guide to the Determination of Human Exposure to Radiofrequency Fields.

Bethesda, Maryland: NCRP, 1993.

[5] P.J. Dimbylow and S.M. Mann, "SAR Calculations in An Anatomically Realistic Model

of the Head for Mobile Communication Transceivers at 900 MHz and 1.8 GHz," Phys.

Med. Biol., Vol. 39, pp. 1537-1553, 1994.

[6] T. Schmid, O. Egger and N. Kuster, "Automated E-field scanning system for dosimetric

assessments," IEEE Trans. Microwave Theory Tech., vol. 44, pp. 105-113, Jan. 1996.

[7] V. Anderson and K.H. Joyner, "Specific absorption rate levels measured in a phantom

head exposed to radio frequency transmissions from analog hand-held mobile phones,"

Bioelectromagnetics, vol. 16, pp.60-69, 1995.

[8] World Health Organization, Environmental Health Criteria 137: Electromagnetic Fields

(300 Hz - 300 GHz). Geneva: WHO, 1993.

[9] S.M. Michaelson and E.C. Elson, "Interaction of nonmodulated and pulse modulated

radiofrequency fields with living matter: experimental results," in Handbook of Biological



14

Effects of Electromagnetic Fields, Ed. C. Polk and E. Postow. Boca Raton, Florida: CRC

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[10] M.A. Stuchly, "Proposed Revision of the Canadian Recommendations on Radiofrequency

-Exposure Protection," Health Physics, vol. 53, pp. 649-665, 1987.

[11] R. Matthes, "Radiofrequency fields: physical characterisation, sources, dosimetry and

measurement," in Non-Ionizing Radiation: Proc. Third Internat. Non-Ionizing RadiationWorkshop, Baden, Austria, April 22-26, 1996, Ed. R. Matthes. Munich: International

Commission on Non-Ionizing Radiation Protection, pp. 201-229, 1996.

[12] Q. Balzano and O. Garay, Dyna TAC exposure measurements. Motorola Report, May

15, 1984.

[13] K.H. Joyner, V. Lubinas, M.P. Wood, J. Saribalas and J.A. Adams, "Radio frequency

radiation (RFR) exposures from mobile phones," Proc. Internat. Congress on Radiation

Protection, IRPA8, Montreal, May 1992, pp. 779 - 782.

[14] O. Gandhi, "Some numerical methods for dosimetry: extremely low frequencies to

microwave frequencies, Radio Science, vol. 30, pp. 161-177, Jan.-Feb. 1995.

[15] M.A. Jensen and Y. Rahmat-Samii, "EM interaction of handset antennas and a human in

personal communications," Proc. IEEE , vol. 83, pp. 7-17, Jan. 1995.[16] Q. Balzano, O. Garay and T.J. Manning, "Electromagnetic energy exposure of simulated

users of portable cellular phones," IEEE Trans. Vehicular Tech., vol. 44, pp. 390-403,

Aug. 1995.

[17] International Commission on Non-Ionizing Radiation Protection, "ICNIRP statement:

health issues related to the use of hand-held radiotelephones and base transmitters,"

Health Physics, vol. 70, pp. 587-594, 1996.

Documents

Radiation Effect_Cellular BTS and Handsets