A Planar Quad-band Band-Pass Filter Employing Dual-Mode Band-Stop Resonators

A compact split-type quad-band band-pass filter employing dual-mode stub-load band-stop resonators is presented in this paper. The basic coupling schematic is originated from frequency transformation methods. Then, a dual-mode band-stop resonator, which can provide two controllable transmission zeros, is employed to replace the two single-mode band-stop resonators to achieve the same response. The filter has been synthesized, designed and simulated in planar microstrip technology to demonstrate the feasibility of the proposal. Comparing with filters based on single-mode resonators. This solution provides a relatively compact footprint, which features an attractive solution for filters’ miniaturization.