Accurate analysis of finite periodic substrate integrated waveguide structures and its applications

In this paper, we present a systematic analysis of periodic structures based on substrate integrated waveguide (SIW) technology. In the periodic structures of interest, the unit cell is a circularly-shaped SIW section, which can be extended to any shape. In the beginning, the propagation constants of both even and odd modes of the SIW periodic structures are accurately extracted with the help of a numerical thru-line (TL) calibration technique, which utilizes two periodic structure sections having different cell numbers as calibration standards. Then, two design examples are showcased to validate the analysis results. The first example is a planar crossover structure using the circularly-shaped SIW coupling section. The other is a bandpass filter that is designed by making use of the stopband characteristics of the proposed SIW periodic structures. Good agreement is observed between simulation and measurement for both examples.