A 27.5–29GHZ SIW cross-coupling filter in LTCC

The study of a four SIW resonant cavities cross-coupled filter for Ka-band is presented in this paper.Positive, negative coupling and cross-coupling between input and output are obtained by using a novel 3-D coupling configuration is applied in LTCC(Low Temperature Co-fired Cemaric).They produce two transmission-zeroes on both sides of passband together,which strengthen the frequency selectivity of the filter.The measured insertion loss is 3.2 dB in 3 dB fractional band width of 5.31%(1.5 GHz),and the measured return loss is greater than 10.8 dB in pass band.The volume of this filter is reduced to 5.3×4.4×0.576 mm3 by using TE₁₀₁ resonant mode and CPW(Co-Planar Waveguide) current probe.