Optimal Design of a Bandpass Cavity Filter with WR229 Input/Output by Integrating the Coupling Matrix Technique with the Trust-Region Framework

This study introduces a bandpass waveguide cavity filter designed for the C-band, centered at 3925 MHz. The design employs an efficient method that integrates two techniques: coupling matrix synthesis and the Trust-Region Framework algorithm for optimization. This combined approach provides a good balance between model simplicity and efficiency while maintaining the robustness and accuracy of the designed filter. Simulation results indicate that the filter achieves a return loss of |S11| ≤ -20 dB and an insertion loss of |S21| ≥ -0.05 dB. Additionally, the filter demonstrates a rejection level of -50.6 dB at 3000 MHz and -21.9 dB at 5000 MHz. The optimized filter’s dimensions in the simulation are 140 × 58.17 × 29.21 mm.