A Ka-band cavity bandpass filter using LTCC technology

This paper presents a simple way to design a bandpass LTCC (Low Temperature Co-fired Ceramic) cavity filter, which has microstrips as I/O ports and via fenses as side walls. This filter works in the Ka-band, and exhibits an insertion loss of 1.5 dB at the center frequency of 35.85 GHz, a rejection more than 20 dB over the passband, a 3-dB bandwidth about 0.5 GHz and in the lower band of 33-34 GHz, the stopband suppression of 60-81 dB is achieved. Besides of the perfect performance, this filter is easy to be integrated to millimetre-wave systems.