Three-order microstrip bandpass filter with two transmission zeros for WLAN/WiMAX applications

Abstract

A simple novel compact three-order microstrip bandpass filter is proposed using half wavelength microstrip line resonators coupled through parallel stub lines. The filter has two signal paths, one through the parallel coupled lines of resonators and other through the electrical coupling between feed lines for which the filter shows two transmission zeros. The proposed filter has a bandwidth of 1 GHz covering WLAN 5.2/5.8 GHz and WiMAX 5.5 GHz bands. The filter is compact and simple structure having very low insertion loss in the passband makes it suitable for wireless application.