Compact microstrip lowpass filter with sharp roll‐off using radial resonator

Abstract

A compact microstrip lowpass filter (LPF) with sharp roll‐off is presented. The proposed filter consists of radial resonator, triangular patch and open stub. The proposed filter has good specifications such as low insertion loss <0.1 dB, high return loss of −20 dB, wide stopband from 4.37 to 19 GHz with −20 dB attenuation level and compact size. The LPF filter has a cut‐off frequency of 3 dB at 4.24 GHz and a high roll‐off rate of 130.7 and finally a high figure‐of‐merit of 23526.