Design of radial microstrip band pass filter with wide stop-band characteristics for GPS application

Abstract

In this paper, a novel compact band pass filter (BPF) is proposed for Global Positioning System (GPS) receivers. The proposed BPF configuration is composed of a low pass filter (LPF) section formed by the coupled line transformer connected with a radial stub and two short circuited stubs embedded within the 50Ω microstrip line connecting the input/output (I/O) port of LPF. The lumped equivalent model of proposed BPF is also presented and analyzed. Simulation as well as experimental results shows very good in-band (pass-band) and out-of-band (≈ 7fc (centre frequency)) characteristics. The 3 dB fractional bandwidth (FBW) is 3.2% of fc, thus satisfying the GPS receiver requirement and the minimum insertion loss (IL) in pass-band is 1.28 dB.