With respect to additional filtering, which would be needed for the suppression of harmonics, there is a waveguide type known as the “waffle iron” which appears to be most adaptable to this requirement. The design literature indicates that a 50 to 70 dB attenuation level over a 10 to 1 bandwidth is achievable. There are areas of further study that are suggested to resolve or further define the problem. These include: (1) narrow-band operation in an unusual design requirement, which warrants some further study to confirm the impact upon noise; (2) the selection of the optimum gain which could range from 3 to 10 dB for each stage should be studied to identify the best overall value for the RFI requirement; (3) noise measurements on CW tubes should be made to confirm the interpretation of present pulsed data converted to CW (there is an expectation that such data will, in fact, be better than that obtained on pulsed operation); and (4) filter capability in relation to size, weight, and attenuation tradeoff. Effects of SSPS RFI on Other Users Transmitting Antenna and Nature of the Transmitted Beam. — The geometry of the transmitting and receiving antenna system is shown in Figures 72 and 73, and Table 16 presents the electrical characteristics of the transmitting antenna. A preliminary investigation of the amplitude distribution for minimal Earth spot which contains 90% of the total energy shows the distribution to be [1 — r2 ]1/2 where r is the radial point on tne transmitting antenna. The power distribution pattern for the transmitting antenna is shown in Figure 74, and the resulting pattern for the receiving antenna is shown in Figure 75. There are other distributions which should be investigated later in the program that can be used to reduce the size of the Earth spot even further; however, these are more complicated and, at best, will only cause a reduction of a few percent. (The receiving antenna is also discussed in this section.) The distributions of the form (1 - r2 ] n are conveniently analytical and are perfectly adequate at this stage of the analysis. System data are summarized in Table 17 for n = 0.. 1/2.1. and 2. TABLE 16 ELECTRICAL CHARACTERISTICS OF THE TRANSMITTING ANTENNA Frequency of operation Total power into transmitting antenna Gain of transmitting antenna Number of Amplitrons in transmitting antenna Power distribution in transmitting antenna
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