Ka Band Novel Concise Sine Substrate Integrated Waveguide Bandpass Filter

A novel concise sine substrate integrated waveguide (SSIW), with both sides metallized via holes periodic undulation, is firstly proposed for developing bandpass filter (BPF) at millimeter frequency range. It has advantages of remarkable simplicity, compact size and low insertion loss. Simultaneously, a broadband microstrip to SSIW transition is proposed. Transition experimental results show less than 2 dB insertion loss at nearly whole Ka passband. Then, several Ka band SSIW BPFs with different passband widths and center frequencies are designed and fabricated. The experimental results demonstrated that the SSIW BPF passband width and center frequency could be designed by using different undulate amplitudes and periods of the SSIW.