Design of a miniaturized K-band SIW filter based on LTCC process

In this paper, a K-band fourth-order substrate-integrated waveguide (SIW) filter based on a low-temperature co-fired ceramic (LTCC) process is proposed for use in satellite receiving systems, which operates in the frequency band from 19 .2 GHz to 21.2 GHz with the in-band return loss (S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>) of less than 24 dB and the insertion loss (S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</inf>) of less than 1.40 dB. The bandpass rejection capability is further improved by introducing a cross-coupling structure in the top- and bottom-resonant cavities, enabling the introduction of an out-of-band transmission zero at 18 GHz and 22.75 GHz, respectively. The overall size of the filter is 4.7 mm×5.2 mm×0.768 mm, which features miniaturization and low profile.