Long-Term Study of 435 MHz Radio-Frequency Radiation on Blood-Borne End Points in Cannulated Rats. Part I: Engineering Considerations

Abstract

To study the effects of exposure to long-term, low-level radio-frequency radiation (RFR) on various physiological systems in a large population of rodents, a complete exposure facility was designed and constructed at the Georgia Institute of Technology. The major components of the facility included a set of circular, stacked, parallel-plate waveguides fed by slotted-cylinder antennas. The waveguides provided a TE10 mode, horizontally polarized field in which the maximal power density occurred midway between the parallel plates. The feed antenna and the parallel-plate waveguides generated a field that radiated outward and was uniform in the azimuthal plane. Thus, animals arrayed along the periphery of the plates were exposed to a uniform 1.0 mW/cm2 field (1.0 microsecond pulse width, 1 kHz pulse repetition rate, 435 MHz carrier). The facility transmitter provided four channels of 435 MHz RFR at 200 W average (continuous wave) or 5 kW peak (pulsed-wave) power; in addition, the transmitter outputs could be combined into a single channel capable of energizing one tier of the stacked parallel-plate waveguide system at 800 W continuous wave or at 16 kW of pulsed waves. To individually house the 200 rodents involved in the study, both biological and engineering criteria were examined and used to design and construct special Plexiglas cages.

Biological effects of electromagnetic radiation

“…Indeed, no changes were observed in exposed humans for a range of hormones as well, including growth hormone, luteinizing hormone, cortisol, melatonin, and others. Research in rats has shown results consistent with these general findings in that no demonstrable effects on hormones, including melatonin, have been reported with low-level RF exposure at 435 MHz (Bonasera et al, 1988;Toler et al, 1988) or at 900 MHz (Vollrath et al, 1997;Heikkanen and Juutilianen, 1999). Mann et al (1998) reported that pineal and serum melatonin levels were not altered by 6 h exposure to a 900 MHz EMF in rats.…”

The radial transmission line as a broad-band shielded exposure system for microwave irradiation of large numbers of culture flasks

“…Back reflection from the lateral boundaries of the plates can be 1) ignored [Bonasera et al, 1988], 2) suppressed by tapered resistive wedges at the edge of the guide [Macrakis, 1960], or 3) suppressed by a guidefilling layer of microwave-absorbing foam. We chose the third alternative and employed a ring (ID Џ 0.419 m; OD Џ 0.533 m) of AEL-4.5 foam (Advanced Electro-Magnetics, Santee, CA).…”

“…A transverse electromagnetic wave is launched into it by an appropriate radially symmetric antenna at its center; the entire unit is terminated, as appropriate, at the lateral plate boundaries. Such devices have been used biologically [Bonasera et al, 1988]. A World War II technology associated with MIT's Radiation Laboratory [Marcuvitz, 1948[Marcuvitz, , 1951, they are modestly well understood electromagnetically.…”

Space efficient system for whole‐body exposure of unrestrained rats to 900 MHz electromagnetic fields

“…Hence, for present studies the exposure system was designed so that the animals could move freely and stay continuously in their cages during and between the exposures where food and drinking water was provided ad libitum. Several RF exposure systems have been developed where animals can freely move in their cages [Guy et al, 1979;Bonasera et al, 1988;Repacholi et al, 1997;Hansen et al, 1999;Wilson et al, 2002]. However, none of these systems seemed to fulfill the requirements of our animal studies as such due to their costs or required space.…”