A Wideband Bandpass Filter with Stepped Impedance Resonator on Microstrip

Abstract

This paper proposes a folded stepped impedance resonator filter with a parallel-coupled structure for size reduction and improved spurious suppression using by the open circuit stub in the stopband. The design concept is demonstrated by using four SIR resonators with the fundamental frequency f0 of 4.5 GHz. For a comprehensive treatment of the filter with open stub, the spurious response can be suppressed. The measured result is in good agreement with the simulated expectation with a 0.2 dB insertion loss and more than 15 dB return loss. Moreover, this filter has a 5 GHz wide range frequency bandwidth response and wide range of the upper stopband is better than 15 dB rejection level and extended from 10 up to 17 GHz. As a result, the proposed filter is quite useful for applications in short rang wireless communication systems.