Hch. Cheung et al., IMPROVEMENTS IN SUPERCONDUCTING LINEAR-PHASE MICROWAVE DELAY-LINE BANDPASS-FILTERS, IEEE transactions on applied superconductivity, 5(2), 1995, pp. 2675-2677
Microwave delay line filters can be designed to specified amplitude an
d phase characteristics using a synthesis procedure which takes into a
ccount multiple reflections and losses in the delay lines. The time do
main synthesis procedure has now been extended so that frequency-depen
dent 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 linear
ity over previously published data on microstrip devices.