A Multi-mode Waveguide with Mode Selective Effect

Mode selective transmission line is one of the potential solutions for the increasing demand of high-speed transmission rate. In this paper, a multi-mode waveguide with mode selective effect is proposed. The proposed waveguide can operate with transverse electromagnetic (TEM) mode over low frequency, which is similar to a parallel plate waveguide, and TE10 mode over high frequency, which is similar to a substrate integrate waveguide (SIW). To verify the mode selective effect of the multi-mode waveguide, the multi-mode waveguide is designed and fabricated in printed circuit board (PCB) process. The electric field distribution and the variation of the attenuation constant with frequency show that the mode selection occurs around the cutoff frequency of the TE10 mode of the multi-mode waveguide. The measurement results of the S-parameters and the propagation constant agree well with the simulation ones in the range of DC-30GHz.