Millimeter-Wave Three-Dimensional Substrate-Integrated OMT-Fed Horn Antenna Using Vertical and Planar Groove Gap Waveguides

A three-dimensional (3-D) substrate integration method by using both the planar dimensions and the vertical dimensions in multilayered substrates for millimeter-wave devices and circuits design is presented in this article. The vertical substrate-integrated groove gap waveguide (SIGGW) is studied first, whose multilayered geometry without metal contact between stacked substrates and wide operating band supporting the single quasi-TE
₁₀
mode with stable propagation features enables it to be a promising vertical waveguide structure with ease of realization. By simultaneously utilizing the vertical and planar SIGGWs, a fully 3-D substrate-integrated orthomode transducer (OMT) consisting of E-plane power dividers, U-shaped connections, and a turnstile junction that are difficult to fulfill in previous works is successfully implemented in the Ka-band. Its compact geometry and significantly performance improvement demonstrate the merits of the proposed method. After that, the OMT is used for feeding a dual-polarized pyramidal horn antenna also with a 3-D substrate-integrated configuration. The overall multilayered antenna module with experimentally confirmed wide bandwidths, high isolations, and stable radiation patterns can still be fabricated conveniently by employing the standard single-layered printed circuit board (PCB) facilities. Taking the advantages of the flexible design freedom and satisfying operating characteristics, the presented design method and devices are valuable to advanced millimeter-wave applications.