A Study of Millimeter Wave SIW Bandpass Filter on Alumina Ceramic Substrate

Two types of third-order cross-coupled millimeter wave substrate integrated waveguide bandpass filters on an alumina ceramic are designed and fabricated. Type I filter consists of three rectangular resonant cavities resonating at the fundamental TE
101
mode. Type II filter can make the transmission zero occur at the lower stopband by introducing TE
102
mode. The type one sample filter shows excellent thermal stability and works at 35.95 GHz with a bandwidth of 400 MHz. The simulated and the measured results of the type I filter both show that the return loss in the passband is more than 15 dB, and the insertion loss is smaller than 2.54 dB. Besides, the fabricated type II filters work well in the MMW T/R module.