This is the same as for the amplitron. Combining this with the filter curve of Figure 4-52 we obtain the noise power density at the earth’s surface as a function of f away from f shown in Figure 10-2. 10. 1. 3 INTERFERENCE LIMITS AND EVALUATION The interference limits as prescribed in Reference 10-1 are: These are plotted on Figure 10-2, where we see that the klystron is estimated to have a narrower band for potential interference than the amplitron. We see also that no problem exists with regular and troposcatter commercial regulations. A selection of 2. 45 GHz is demonstrated to be reasonably good. The klystron noise is essentially below the isotropic requirement outside of the 2.4-2. 5 GHz band, and noise for both klystron and amplitron is below the natural lines at 1. 4 GHz and 1.7 GHz for the 60 dB antenna requirement. The amplitron extends beyond the industrial band (+2 50 MHz, -150 MHz) for isotropic requirements and does not meet the 60 dB requirement above the high end of the industrial band. The reason for this is that the added filter attenuation extends only to the vicinity of -80 dB to -100 dB before leveling out. The natural lines could be further protected by bringing waveguide cutoff into play above 1. 7 GHz. The design represented in this study is 12 cm wide, which cuts off at 1. 25 GHz, so that the width would have to be decreased to about 8 cm (integral factor of radiator diameter of 48 cm) for a cutoff at 1. 87 5 GHz. This produces additional center frequency attenuation and adds weight to the antenna (more walls) so that it may be better to build only the amplitron-to-array waveguide feeds with the necessary cutoff characteristics. This area should be examined in a follow-on study. 10.2 HARMONIC CONSIDERATIONS The interference on the earth’s surface caused by MPTS harmonic generation is a function of the following parameters:
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