Microstrip cross-coupled stepped-impedance line bandstop filter

Abstract

This paper presents a novel design of a wide spurious-free bandstop filter using cross-coupled stepped impedance lines. A measured bandstop filter with 10-dB bandwidth of 160 MHz is designed at the center frequency of 1.0 GHz, and it shows no spurious responses up to 5.2 GHz. As a preliminary investigation, the filter is tuned electronically using ferroelectric thin film varactors.Index Terms -Dual-mode resonator, bandpass filters, microstrip filters.