Attenuation and time delay equalizer for a waveguide filter

An arrangement for the equalization of attenuation and time delay in a microwave filter utilizing waveguide technology, the filter having time delay characteristics which vary as a function of frequency, comprising an equalizer composed of a multi-circuit cavity resonator coupled via a first coupling aperture to a waveguide which is connected to the filter, the multi-circuit cavity resonator having a longitudinal axis and including at least two individual waveguide sections coupled to each other via a second coupling aperture, the coupling apertures being dimensioned so that the individual waveguide sections and the waveguide are critically coupled with respect to time delay characteristics so that the time delay characteristics of the filter become substantially frequency-independent over a wide band of frequencies, the improvement wherein:

• said multi-circuit cavity resonator includes power-absorbing tuning means for tuning all of said waveguide sections to substantially the same quality factor;
• said second coupling aperture coupling said waveguide sections with each other presents a stepped cross section defining a first area and a second area having a larger cross section than said first area;
• and
• said multi-circuit cavity resonator includes at least two screws arranged symmetrically with respect to said longitudinal axis of said multi-circuit cavity and protruding laterally into said second coupling aperture in said second area of larger cross section, said screws influencing the time delay of said equalizer arrangement as a function of their depth of penetration into said second area.