harmonic frequencies (the gain is assumed to be between 87 dBi and 27 dBi), as well as an uncertainty in the amount of harmonics present in the SPS waveform (the power in the harmonics is assumed to be between -70 dBc and -120 dBc where dBc denotes dB relative to the power in the carrier). The estimates of harmonic level of 10 mw/cm are indicative of a highly focused SPS transmitting antenna at harmonics with antenna gain at the harmonics comparable to the gain at the fundamental. The likelihood of having a highly focused SPS transmitting antenna at harmonics is not known at the present time. If the gain of the SPS transmitting antenna at harmonics is comparable to the gain at the fundamental, then the beamwidths at harmonics and fundamental can also be expected to be comparable. Thus the areas on the surface of the earth illuminated with 10 mw/cm harmonic levels can also be expected to be highly localized. However, there is no guarantee that these locations could be predicted a priori or that they would remain stationary Estimates of 10 mw/cm , on the other hand, are indicative of a defocused transmitting antenna at SPS harmonics, and if such conditions exist, these signal levels could be expected over a significantly large portion of the earth surface. 3. INTERFERENCE TO GENERAL ELECTRONIC EQUIPMENT The behavior of general electronic equipment such as TV, FM radio, and electronic computers in high-level microwave fields is not entirely understood at the present time. While it is known that these systems can be affected by microwave fields of the magnitude projected for SPS, the ability to predict these interactions has not been developed. Experimental data is primarily limited to laboratory tests conducted by a few experimenters. The purpose of the following discussion is not to precisely predict the SPS interference thresholds, but rather to gain some coarse estimates of the levels of microwave fields that can cause interference. This section of the report will also describe some of the interference mechanisms that are active in these instances. The mechanisms that are involved when a microwave signal interferes with electronic devices are varied and complex. With TV, for example, a 2.45 GHz interfering signal would be many megahertz higher in frequency than the normal TV operating frequencies. Laboratory tests of TV’s in gigahertz microwave fields have shown that the primary interference mechanism is due to the leakage of signals directly into the chassis. Interference coupled through the antenna system is secondary. Leakage signals, once they are within the chassis, produce interference by coupling into rf sensitive circuits such as mixers, IF amplifiers, and detectors. A priori prediction of interference of this nature is all but impossible given the current state of electromagnetic compatibility analysis.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==