Improvements in superconducting linear phase microwave delay line bandpass filters

Microwave delay line filters can be designed to specified amplitude and phase characteristics using a synthesis procedure which takes into account multiple reflections and losses in the delay lines. The time domain synthesis procedure has now been extended so that frequency-dependent loss and delay line dispersion can also be allowed for. Meanwhile experimental results on linear phase microstrip and coplanar filters show significant improvements on stopband attenuation and phase linearity over previously published data on microstrip devices.<>