wholly on the concept that the birds are not perturbed by the microwave emissions, and good evidence for this is provided. In one of the few controlled experiments to evaluate radar influence on birds in flight, microwave radiation in the frequency range 600 MHz-10 GHz was used as a perturbing and/or tracking source and no effect was observed. Yakobi (13) has reported experients in the Soviet Union in which radar failed to affect the orientation of birds under controlled experimental conditions. It was further concluded that reported cases of birds being scattered by radar emission in reality were a reaction to the sight of the rotating antenna. Pigeons being fed in a microwave radiation field of 3 mW/cm2 are reported to have eaten without concern, and this included the area near the radar horn, where the power density was estimated to be 52 mW/cm2 (14). Similarly, the documented cases of birds roosting or nesting in or near powerful radars are numerous. So it would appear that a microwave radiation environment of 23 mW/cm2 is unlikely to disturb birds. CONCLUSION It would appear that thresholds for biological effects from short-term microwave irradiation are well above the maximal power density (1 mW/cm2) that is tentatively projected at or beyond the area of exclusion of a rectifying antenna. However, it has to be remembered that no experimental study has been performed that approaches even remotely the 30 years or more that the solar power satellite would be operative. REFERENCES 1. H.P. Schwan, Advances in Biological and Medical Physics, J.H. Lawrence and C.A. Tobias, eds., p. 147, Academic Press, New York, 1957. 2. C.C. Johnson and A.W. Guy, Proc. IEEE 60, 692, 1972. 3. S.M. Michaelson, Proc. IEEE 60, 389, 1972. 4. S.F. Cleary, Health Phys. 25, 387, 1973. 5. J.C. Mitchell, EM Radiation: Effects on the Eye, in AGARD Lecture Series No. 78 on Radiation Hazards, NTIS No. AD A015200, pp. 5.1-5.6, 1975. 6. R.L. Carpenter, G.J. Hagan, and G.L. Donovan, in Symposium on Biological Effects and Measurement of Radiofrequency Microwaves, D.G. Hazzard, ed., HEN (FDA) 77-8026, pp. 352-379, 1977. 7. M.M. Zaret, LT. Kaplan, and A.M. Kay, Biological Effects and Health Implications of Microwave Radiation, Symposium Proceedings, S.F. Cleary, ed.. Publication BRH/DBE 70-2, pp. 82-84. 1970. 8. I.R. Petrov, ed., Influence of Microwave Radiation on the Organism of Man and Animals, NASA Technical Translation TTF-708, NASA, Alabama, 1972. 9. J. Healer, Biological Effects and Health Implications of Microwave Radiation Symposium Proceedings, S.F. Cleary, ed., Publication 70-2, pp. 90-97, 1970. 10. S. Baranski and P. Czerski, Biological Effects of Microwaves, Dowden, Hutchinson and Ross Inc., 1976. 11. J.C. Mitchell and M.S. Hurt. The Biological Significance of Radiofrequency Radiation Emission on Cardiac Pacemaker Performance, SAM-TR-76-4, 1976. 12. E. Eastwood, Radar Ornithology, Methuen, London, 1967. 13. V. Yakobi, Birds’ Nests in Radar Antenna, Aviatsiya i Kosmonautika 1, 45, 1969. 14. F.R. Hunt, Pulsed Microwave Radiation of Birds, Presented to Associate Committee on Bird Hazards to Aircraft, Ottawa, Canada, 1975.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==