Advanced filter design using cross-coupled networks with higher-order resonances

A new class of cross-coupled networks is presented for the advanced design of microwave filters. By including nodes for higher/lower-order mode resonances, a broadband model is obtained which partly eliminates the narrowband restrictions found in current coupling matrix approaches. Several bandpass filter examples for WR75 waveguide applications are presented. It is demonstrated that the new cross-coupled network correctly predicts all resonance effects over a wide frequency range. The process is validated by comparison with in-house and commercially available field-theory-based codes.