Design and simulation of a parallel-coupled microstrip bandpass filter

Bandpass filters play an important role in wireless communication systems. Both transmitted and received signals have to be filtered within certain bandwidths. A parallel-coupled microstrip bandpass filter is designed through the calculation of even-mode and odd-mode characteristic impedances of coupled line pairs and the computation of physical dimensions of these coupled lines. Simulation of the filter shows that the insertion loss is less than -0.4 dB and the reflection is less than -19 dB around the filter midband frequency.