Design and average power handling capability analysis of substrate integrated waveguide filters with wide stopband

In this letter, we propose a method to extend the stopband of substrate integrated waveguide (SIW) filters. Utilizing this method, we design and optimize a K-band filter. The proposed filter is based on the SIW with rectangular cavity structures. The coupling coefficient method is applied to design the SIW filter. The positions to suppress high-order modes from the magnetic field distribution at the high-order harmonic frequency are investigated. By introducing slots in the side wall through-holes, the suppression effects of high-order modes are achieved. The upper stopband is broadened while the resonance structure and size of the filter are maintaining. The center frequency, the bandwidth and the out-of-band rectangular coefficient (40 dB/1 dB) of the designed SIW filter are 25.875 GHz, 3.25 GHz, and 1.89, respectively. Furthermore, the bandwidth at the 40 dB stopband is as large as 40 GHz. The designed filter is fabricated by silicon-based micro-electromechanical systems processes such as lithography, electroplating, and deep silicon etching. The measured results of the fabricated SIW filter are in good agreement with the simulated results. Finally, a simplified analysis method of average power handling capacity of SIW is proposed, and the results are more accurate by introducing the temperature feedback mechanism of electrical conductivity.