Abstract: A variable Q reflection mode filter has a three-port circulator, one port of which is terminated by a one-port filter. The filter includes a ladder network of resonators, successive of the resonators having progressively reducing Q values. The filter increases the overall 3 dB resonance point of the filter to reduce the unloaded Q factors required for particular applications. The filter may be arranged to provide a maximally flat response, an equiripple response, or a quasi-ripple response. Transmission zeros may also be incorporated to further enhance the effective unloaded Q.