Spurious Pass-Band Suppression in Coupled-Serial-Shunted Lines Wideband Band-Pass Filters

Abstract

In this paper, a synthesis method is presented for Chebyshev type II band-pass filters in the microwave frequency range. We investigate the cause of the second harmonic passband of coupled-serial-shunted lines bandpass filters. Filters are employed substrate suspension, wavy-edge coupling, ring resonators, defect ground structure (DGS), and a combination of the wavy-edge coupling and ring resonators may be used and were investigated to suppress the harmonic pass-band. With a combination of the wavy-edge coupledlines and ring resonators, the harmonic pass-band of the parallelcoupled line filter is rejected more effectively. Several filters are fabricated and measured to demonstrate the design.