Analytical Design of Two-Mode Dual-Band Filters Using E-Shaped Resonators

This paper presents a novel analytical approach for designing two-mode dual-band bandpass filters using E-shaped resonators. Based on the dual-band coupling matrix, the dimensions of the filter configuration are extracted via even- and odd-mode analysis of E-shaped resonators. The back-to-back E-shaped resonators provide the out-of-phase property by coupling at specific edges, and it produces good selectivity for dual-band characteristics. The proposed filters have the advantage of compact size and satisfy various requirements of filter orders and coupling coefficients at both passbands. The transmission zeros are successfully introduced into each passband in both filters. To verify the proposed method, two filters are implemented using microstrip technology. The measured results exhibit two-mode dual-band bandpass responses and agree well with simulations.