Quarter Wave Resonator based Microstrip Bandpass Filter using Asymmetrical coefficients

Abstract

This paper presents a new concept of bandpass filter design based on quarter-wave resonator which covers ISM band (2.4-2.48 GHz) can be used for applications such as wireless fidelity (Wi-Fi) and Global System for Mobile communication (GSM). A fifth-order Butterworth bandpass filter is designed using standard filter coefficients with fractional bandwidth of 50% for the center frequency of 2.1 GHz. Filter design is achieved using quarter-wave resonator, and the obtained response satisfies the desired filter specifications. The insertion loss of 21 dB is achieved at the cutoff frequency of 2.1 GHz. The passband frequency of 1.877 GHz to 2.772 GHz is achieved in the proposed design. The standard coefficients of the Butterworth filter were modified to propose a new type of asymmetrical filter coefficients. The designed filter has better response than existing method in terms of bandwidth and insertion loss. The designed Bandpass filter has a passband frequency of 1.8 GHz to 2.7 GHz. Therefore, the designed bandpass filter can be used for both Wi-Fi and GSM applications simultaneously.