Miniaturized 38GHz Circular Substrate Integrated Waveguide Band Pass Filter using Low Temperature Co-Fired Ceramic Technology

This study presents design approach for realizing miniaturized Substrate Integrated Waveguide (SIW) Band Pass Filter (BPF) using Low Temperature Co-fired Ceramic (LTCC) technology at TMRND’s LTCC Lab. Design method for the SIW BPF is based on the circular cavity structure with four pole Chebyshev and operating at center frequency of 38 GHz. This SIW BPF is an important part of the Remote Antenna Unit (RAU) transceiver for the Radio over Fiber (RoF) system. Two types of circular SIW BPF have been designed and investigated in term of performance and structure size which are planar SIW BPF and compact SIW BPF. Both SIW BPF were developed using LTCC Ferro A6M materials with dielectric constant of 5.8, loss tangent of 0.002 and metallization of gold. The insertion loss for planar SIW BPF and compact SIW BPF were measured at 6.2 dB and 6.3 dB, respectively. The passband return losses for both types of the SIW BPF were measured at more than 10 dB. The size of the compact SIW BPF is 6.94×6.94 mm2 meanwhile size for planar SIW BPF is 12.15×4.145 mm2. The size of the compact SIW BPF is reduced to nearly 10% compared to a planar SIW BPF structure.