An efficient analytical model for microstrip spurline band-stop filter design

An efficient analytical model to design wideband microstrip spurline band-stop filter (BSF) is proposed. The geometrical parameters of the BSFs are optimized using simulation for the entire range of the desired operating frequency (1-5 GHz) and the results indicated relatively inferior performance of the filters designed using conventional analytical model. Whereas, in the proposed model, a mathematical function is found by curve fitting of the optimal data set of geometrical parameters optimized by simulation. Therefore, the filters designed using the proposed model achieve almost optimal performance in terms of rejection ratio, bandwidth, and so on, and a better match between desired and actual operating frequency as compared with the conventional design model. To corroborate the claims, the filter prototypes designed using the proposed and conventional models are fabricated and tested. The measured results showed agreement with the simulation results and proved effectiveness of the proposed analytical model to design spurline BSF. The error limit for the proposed model is found within ±0.005% of the optimal design.