Temporal Coupled-Mode Theory and the Combined Effect of Dual Orthogonal Resonant Modes in Microstrip Bandpass Filters.

We propose a temporal coupled-mode theory for the design of microstrip bandpass filters with multi-resonant modes and reveals the mechanism of the filters based on multi-coupling and energy conservation theorem. As an example, the combined effect of the two orthogonal modes in dual-mode filters is analyzed in detail. By simply tuning the coupling efficiencies of the two resonant modes, two K-band integrated microstrip bandpass filters have been designed and demonstrate opposite asymmetric transmission responses. Both simulation and experiment results agree well with the theoretical analysis, which provides a new approach for filter design and optimization. [ABSTRACT FROM AUTHOR]