Design and Development of A SIW based Narrowband Bandpass Filter In LTCC Technology

A SIW based five-pole narrowband bandpass filter (BPF) has been designed and implemented in low-temperature co-fired ceramic (LTCC) technology. The problems associated with a narrowband BPF in LTCC technology are discussed in detail. An X-band filter with a fractional bandwidth of 230 MHz is implemented at 11.575 GHz. The filter is integrated with a back-to-back CPW-to-SIW transition for measurement purposes. The measured passband insertion loss of the transition integrated filter at the passband center frequency of 11.38 GHz is 3.194 dB. The filter provides an excellent out-of-band response, rejection being more than 30 dB below 11.13 GHz and above 11.63 GHz the passband.