Ultra wide pass-band, absorptive band-reject filter

An ultra wide band-pass, absorptive band-reject filter comprising:

• a pair of quadrature hybrid couplers cascaded and coupled by a phase shifting element and a matched pair of band-reject filters in two parallel paths;
• wherein a respective one of the matched pair of band-reject filters is connected in each of the parallel paths, and the phase shifting element is connected in series with the band-reject filter in one of the parallel paths,
• wherein each of the band-reject filters is configured to reject signals in a desired reject frequency band, the quadrature hybrid couplers each have an insertion loss amplitude crossover of signals propagated to terminals across the coupler that coincides with the reject frequency band, and the phase shifting element is selected to have a phase shift of 180 degrees at frequencies in the reject frequency band, and
• wherein a band-pass to band-reject frequency range ratio exceeding 100:1 and up to ranges of 4000:1 or more is obtained,
• whereby an absorptive rejection response is provided in the reject frequency band while a very wide pass-band frequency range is maintained.