Dual directional H-guide coupler

The H-guide [1] is a useful dielectric waveguide that can be integrated with regular microstrip circuits at microwave frequencies (8 to 14 GHz) using a wideband microstrip to H-guide transition [2]. The thin, single-mode H-guide can feed wideband antennas such as the H-guide aperture-based antenna [3], or form microwave devices such as waveguide-based directional couplers. Previously, dielectric waveguides in the form of optical fibers have been used to form directional couplers [4]; however, multimode complexities due to multimode fibers can be problematic. Non-Radiative Dielectric (NRD) guide couplers have been designed by using slots in a metallic plate [5], or by using a slab of dielectric [6] between two dielectric waveguide transmission lines. In this paper, the thin single mode H-guide as described in [2] is used to form a 1.27 mm thick, six port dual directional coupler with dual coupled lines to lessen the effects of higher order modes.