Concurrent Multi-Mode Excitation for Mode Division Multiplexing over Substrate Integrated Waveguides

This article presents an approach for achieving a concurrent dual-channel link over a single substrate-integrated waveguide (SIW) by designing couplers to selectively excite the first two TE modes. The proposed design was fabricated and experimentally characterized to verify its performance. The TE10 and TE20 channels achieved a measured 4 GHz and 3 GHz 10-dB return loss fractional bandwidths (FBWs) from 11-15 GHz and from 10.2-13.2 GHz respectively. The insertion losses for TE10 and TE20 were less than 1.0 dB and 1.5 dB respectively with greater than 40 dB of isolation measured between the two channels. To the best of our knowledge, this is the first demonstration of a dual-mode SIW link for which both channels can be operated over the same frequency range. The 2.2 GHz of bandwidth overlap in addition to the high isolation between the two channels enables true full duplex communication for high-data rate chip-to-chip communication applications.