TABLE 2. Gain and Side Lobe Estimates for VLA Antennas threshold of harmful interference, at least with the most compact antenna configuration. It is also possible that scattering by subreflector supports may produce side lobes which will preclude pointing as close to the satellites as the angles in Table 2. The most that can presently be said is that for some observations, particularly those of lower angular resolution, the zone in which satisfactory mapping is precluded is probably not much less than 24° wide in deciination. It will be realized, of course, that the level of thermal radiation from a satellite is similar to the flux density of many of the stronger cosmic radio sources. The positions and flux densities of such sources are accurately known, and their responses can be calculated with precision and subtracted from maps of other objects. The satellites, however, would be expected to vary relatively rapidly in flux density and position as they maneuver to track the sun and hold their stations in orbit. Now consider the transmitter-generated radiation, which is much more dependent on presently unknown design details than is the thermal radiation. At a few hundred km from a rectenna, the 2.45-GHz power signal from the corresponding satellite would be received at a level of about -60 dB W in an isotropic radiator. This is about 13 dB over the threshold for overloading of the parametric amplifiers. The 18 to 21-cm band would require some additional filtering, but for the other bands 2.45 GHz is below cutoff for the input wave guides. The second harmonic, for which a relative level of -40 dB will be assumed, would produce about -100 dB W. It can also be generated from the
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