A new approach to microstrip coupled-resonator bandpass filter design

In this paper, a new approach to microstrip coupled-resonator bandpass filter design is proposed. The usual procedure of ladder prototype synthesis and ladder into coupled resonator prototype conversion is used. Instead of semi-empirical approach to determine gaps, a calculation method based on odd/even impedances (Zo and Ze) and electromagnetic field density distribution along the resonator is introduced. The proposed approach is verified by example of several S-band bandpass filters design for active phase array radar system. Full EM-simulation in Ansys HFSS is used. Simulation results confirm good working ability of proposed approach.