A Waveguide Filter as Low Loss Delay Element for Direct DCPQSK Demodulation

A waveguide delay element for direct DCQPSK demodulation operating at 14 GHz is presented. A temperature stable 16.7 ns delay is achieved by a single linear phase dual-mode filter. The device shows a compactness and hightness comparable with a microstrip solution, but displays a much lower insertion loss. This permits a significant relaxation of some critical demodulator specifications.