Compact Wideband Bandstop Filter With Directly Controlled Rejection

Abstract

This brief presented a wideband bandstop filter (WBBSF) with compact size and five transmission zeros, which is based on a symmetrical three-layer ring structure comprising equivalently high-impedance phase-shift section, coupled lines, and short-stubs. The WBBSF based on multi-mode resonators can be directly synthesized from the desired rejection, and its transmission zeros and bandwidth are controlled by only two characteristic impedances. For validation, the calculations, simulations, and measurements have also been done for wideband bandstop filter. Good agreements among the calculated, simulated, and measured results are observed.