Study type: Medical/biological study (experimental study)

Microwave-induced pressure waves in mammalian brains. med./bio.

Published in: IEEE Trans Biomed Eng 1983; 30 (5): 289-294

Aim of study (acc. to editor)

To study direct measurements of acoustic pressure waves in brains of rats, cats, and guinea pigs irradiated with pulsed 2.450 and 5.655 GHz microwaves. A small hydrophone transducer was surgically implanted in brains of animals.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure 2: 5.655 GHz
Modulation type: pulsed
  • power: 200 kW peak value

Exposure 1

Main characteristics
Frequency 2.45 GHz
Type
Modulation
Modulation type pulsed
Pulse type rectangular
Additional info

pulse widths of 2.5 or 5-6 µs, pulse rates of 2 and 20 Hz

Exposure setup
Exposure source
Setup Elmed loop applicators or an open-ended waveguide were placed close to the animal's head.
Additional info For one cat, three-pulse bursts of 2.45 GHz were applied with interpulse spacing varied over a range of frequencies centered on the apparent "ringing" frequency of the brain observed in the single-pulse irradiation.
Parameters
Measurand Value Type Method Mass Remarks
power 3 kW peak value - - -

Exposure 2

Main characteristics
Frequency 5.655 GHz
Type
Modulation
Modulation type pulsed
Pulse width 0.5 µs
Pulse type rectangular
Additional info

pulse rates of 2 and 14 Hz

Exposure setup
Exposure source
Chamber The MW-anechoic chamber was 1.25 x 1.25 x 2.5 m.
Setup The heads of the animals were located on the centerline of the horn at a distance of 5-30 cm. In most experiments, the animal was placed in the prone position facing the horn. When a large artefact was detected, the animal was moved farther away or to a perpendicular position.
Parameters
Measurand Value Type Method Mass Remarks
power 200 kW peak value - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The data indicate that pulsed microwaves induce acoustic pressure waves in the brain. Hydrophone output waveforms and analysed spectra show that fundamental and second harmonics were nearly identical to those predicted by the thermoelastic theory (thermoelastic expansion).

Study character:

Study funded by

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