Synthesis of Dual-Band Filtering Responses with Wideband Characteristics

A novel approach to develop a dual-band filtering response with wideband characteristics is presented in this paper. The order, bandwidth, and return loss for each passband are designated independently, devoid of any optimization or iterative processes. The proposed synthesis commences with single-band synthesis in the bandpass domain utilizing an innovative function combination design. The coupling network matrix can be derived from the synthesized dual-band polynomials and converted into a format that matches the specified topology. Three synthesis examples are shown to illustrate the efficacy of the proposed methodology. This method is appropriate for guiding the design of filtering antennas and other multifunctional circuits.