Compact wide-band bandpass filter using dual-mode capacitance loaded meander square ring resonator with open stubs

Abstract

A novel design of a dual-mode meander square ring resonator with two open stubs for a wide band-pass filter is presented. The input and output of the filter use a direct feed， then the filter exhibits bandstop behavior. When two open stubs are connected to the location opposite to the ports ， a wide passband and sharp rejections are created for the filters. Four identical branches are loaded as capacitance on the outside corner of the mender loop resonator, and the miniaturization design of the filter is realized. Simulated results show that the center frequency of the filter is 4.72GHz and the relative bandwidth is 43% .The insertion loss is less than 1dB and return loss is more than l3dB.Four transmission zeros are found in both the lower and upper stopbands, so the filter exhibits sharp attenuations near the passband.