A New Microstrip Dual-Band Bandpass Filter Design using SIRs and Open Stubs

Abstract

A novel design of microstrip dual-band bandpass filter is presented in this article. The structure contains stubs loaded feeding and Stepped Impedance Resonators. The design allowed achieving a harmonic free characteristic for the filter and achieving a good and stable out of band attenuation. The measured return losses are better than 20 dB and the measured insertion losses are around 3dB in both passbands. The outof- band attenuation levels are 40dB up to 10GHz. The overall measured results are in good agreement with simulations and the filter dimensions are 18×16 mm². The filter is designed to work at the center frequencies 3.45 GHz and 5.75 GHz to suit WLAN and WIMAX applications