A 26 GHz Partially Air-Filled Substrate Integrated Waveguide Filter Based on LTCC

In this work, a partially air-filled substrate integrated waveguide filter (AFSIW) based on Low Temperature Co-fired Ceramic (LTCC) technology is proposed. In order to improve the performance of the regular substrate integrated waveguide (SIW) filter, two cavities were embedded into each resonator. Two kinds of SIW filter with center frequency at 26.3 GHz and 26.4 GHz were designed and manufactured. The simulation results show that the minimum insertion loss of the AFSIW filter is 0.51 dB and the return loss is more than 20 dB which are better than those of the filter without air-filled cavity. The measured results of the two filters are consistent with the simulation results.