Parallel coupled microstrip band pass filter design using EM-analysis

Electromagnetic analysis has become an important tool in the design and simulation of microwave circuits. More accurate prediction of circuit performance and the effect of package and other parasitic can be made using such tools. A fourth order parallel coupled microstrip band pass filter was designed using Chebychev low pass prototype and was simulated on harmonica and further on EM-analysis tool Sonnet to take into account the physical layout and packaging effects. The filter was designed to operate at a center frequency of 1 GHz and a B.W. of 200 MHz with pass band ripple of 0.01 dB. The measured results show insertion loss of -1.2 dB and BW of 220 MHz at centre frequency of 1 GHz. The results show that EM analysis gives a better prediction of the response of actual filter.