Abstract: The passband ripple of a filter arrangement, including an amplifier and a bandpass filter, is tuned to a desirable level at the expense of the output return loss of the filter arrangement. Thus, the output return loss is increased as a result of reducing the ripple. To reduce the output return loss to a desired level, a lossy network is coupled to the output of the filter. The output return loss is reduced by twice the insertion loss of the lossy network. The insertion loss of the lossy network can be compensated for by increasing the gain of the amplifier.

Abstract: A combination notch/bandpass filter uses first and second adjacently-located cavities in the conductive housing to respectively provide a tunable, first-stage notch filter and a second-stage bandpass filter. An opening in a wall provides a passage for energy from the first cavity to the second cavity. In the first cavity, a resonator is located adjacent the opening, along with a notch-filter tuning member having one end arranged opposite the resonator and spaced therefrom by a distance to permit the wide end of a coupler to be suspended therebetween. An elongated portion of the coupler carries filtered energy from the first cavity to the second cavity.

Abstract: A combined resonator-cavity filter includes a number of cavity structures designed for cooperative arrangement within a housing. The resonator cavities are constructed and arranged to pass energy in an assigned frequency band. The cavities include a first cavity structure having a corresponding cavity volume and constructed to provide a first Q, and a second cavity structure having its corresponding cavity volume and constructed to provide a second Q. The cavity volume corresponding to the second cavity structure is less than the cavity volume corresponding to the first cavity structure. Other aspects are directed to the arrangement and uses of sets of such cavity structures as part of a combined duplexer-receiver having the same housing.