Multiple Branch-Guide Directional Coupler Using TE/sub 01/-Mode Semicircular Waveguide (Short Papers)

This short paper describes experimental results derived from a newly devised branch-guide directional coupler using a TE/sub 01/-mode semicircular waveguide. The length of an experimental 0-dB coupler is about 150 mm, which is one-third shorter than the conventional coupled wave-type 0-dB coupler, and the loss is decreased in proportion to the reduction in length. Using this coupler, it is possible to manufacture more compact millimeter-wave diplexers with reduced insertion loss.