Concurrent Dual Polarization Dielectric Waveguide Interconnect using Inverse Designed Dual-Mode Surface Antenna Launcher

We present the design of a dual-mode metallic antenna coupler that can simultaneously couple two separate signals into orthogonal polarizations of a dual-polarization metal-coated dielectric waveguide. The coupler sits on the top surface of the waveguide and features two side-by-side excitation ports, which excite the Ex polarization of the waveguide when driven differentially and the Ey polarization when driven in common mode. Design is done using random coordinate ascent (RCA). Simulation results show that both modes can be operated simultaneously in the 88.6 – 94 GHz range, achieving 6% fractional bandwidth and a coupler-to-coupler channel insertion loss of 3dB per channel. Due to the symmetric design of the coupler, the interconnect has theoretically zero cross-coupling between the two polarization channels. The design is also amenable to fabrication via standard microfabrication techniques due to its single-plane surface coupling nature. To the best of our knowledge, this is the first realization of a concurrent dual-mode dielectric waveguide which leverages a single surface antenna for coupling into both modes simultaneously.