Implementation of the SIW Klopfenstein taper using a comb-SIW

The comb-substrate integrated waveguide (comb-SIW) and the SIW Klopfenstein taper are investigated and presented in this paper. By introducing comb-SIW, the characteristic impedance (Z_C) of a SIW can be modified without changing the cut-off frequency (f_c) and the width or height of the SIW. The Z_C of a SIW can be increased by up to about 1.8 times using comb-SIW. Comb-SIW is used to implement the SIW Klopfenstein taper as an application of comb-SIW. The simulation and measurement results are presented to verify the analysis. The measured return loss of the SIW Klopfenstein taper is over 17.2 dB from 13 GHz to the TE₂₀ mode f_c.