Improvement of Spurious Responses for Bandpass Filters Using Open-Ended Microstrip Coupled-Line

Abstract

This paper describes improvement of spurious responses for bandpass filters(BPFs) using an open-ended coupled-line. First, we examine the resonance characteristics of the tap-coupled open-ended resonator. Secondly, we examine the effectiveness of tap-coupling method to the BPF consisting of an open-ended microstrip coupled-line. Furthermore, improvement of the spurious responses of an edge-coupled BPF consisting of microstrip coupled-line is also examined theoretically and experimentally. It has been confirmed that proposed method is useful for improving the spurious responses of the BPFs consisting of the open-ended microstrip coupled-line.