Design and Simulation of 3.9 GHz Microstrip Parallel Coupled Line Band Pass Filter

Band pass filters play a major role in wireless communication systems. Transmitted and received signals have to be filtered at a certain frequency with a specific bandwidth. In this paper a microstrip parallel coupled-line band pass filter operating at the centre frequency of 3.9 GHz with wide bandwidth of 1.25 GHz is designed and simulated using CST. The proposed bandpass filter is tuned to 3.926 GHz with dimension of 60 mm x 30 mm by adjusting the gap and to 3.861 GHz by adjusting the width between the coupled lines. The filter gives an insertion loss of -2.2 dB, return loss of -17.3 dB and –3 dB bandwidth of 1.25 GHz. The effect of the width and gap of the coupled line on the center frequency is discussed.