WT4 millimeter waveguide system: Line and repeater equalization

The WT4 millimeter waveguide system requires equalization of the loss and delay of the line, which is made up of both the waveguide itself and the diplexer (waveguide channelizing filter) arrays. In the lower portion of the band (40 to 60 GHz) there is considerable linear delay (as much as 30.5 nsec per 400 MHz at 40 GHz), which is equalized by using a folded tape meander line delay equalizer. The remaining delay and amplitude deviation from the desired transfer characteristic is further reduced by field-adjustable trim equalizers. In this paper, we describe the equalization and measurement philosophy for the WT4 system and also the technologies used in achieving the resulting degree of equalization. We put special emphasis on the description of trim equalization because line equalization has been described in detail in a previous publication.
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