Compact SIW directional filter using substrate integrated circular cavities

Abstract

AbstractIn this paper, a novel directional filter (DF) is proposed and implemented using substrate integrated waveguide (SIW) technology which exhibits the advantages of compact size and simple structure. The proposed DF is realized by two half mode substrate integrated waveguides (HMSIWs) and two substrate integrated circular cavity (SICC) resonators operating in the TM110 degenerate modes in which an aperture is utilized to realize the coupling between HMSIWs and SICCs. Two slotlines with appropriate dimensions, etched on the top and bottom planes, are utilized in order to control coupling strength between two cascaded SICC resonators. The proposed two-circular cavity SIW DF at 12.3 GHz is designed and fabricated with a normal printed circuit board process. Measured and simulated results indicate that the DF has a 3.25% bandwidth, and the return loss as well as isolation are better than 10.5 and 15 dB, respectively.