6.6 TOLERANCE AND ATTENUATION 6.6.1 FREQUENCY TOLERANCE Near the center of the transmit array, the slotted waveguide length between amplitrons is 1.92 meters as determined by fully packing with radiators 48 cm in diameter. A change in frequency or a change in waveguide width will cause the subarray to frequency scan if the direction of rf power flow is unilateral. If this occurs slowly, it can be compensated periodically by the jack screws near the corners of the subarray. If the amount of frequency scan is different for each subarray, a change in frequency will not fully compensate. To maintain subarray beam squints within one arc minute (same as mechanical attitude control requirement) requires that the phase error over 1.92 meters (including the amplitron) be less than: The frequency stability can be found as follows. The phase shift down the guide is given by:
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