6.6.2 WAVEGUIDE DIMENSIONAL TOLERANCES The tolerable change in waveguide width to maintain beam pointing to one arc minute can be found as follows. The beam pointing angle is given by: where 6 is measured as a negative angle toward the feed end. dx is the spacing between a pair of slots. Errors in properly locating the slots will produce random phase errors. The rms phase error due to rms location errors is given by: The slot conductance is relatively insensitive to slot width. The resonance changes, however, with length. The effect of temperature variation and waveguide length and width causes beam scanning in the manner of a frequency change. The maximum temperature variation due to the diurnal rotation of the antenna relative to the sun was estimated from the data of Figure 3. 3-23 of Section 8, on the assumption that waveguide
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