Connection structure including a coupling window between a dielectric waveguide line in a substrate and a waveguide and having plural recesses formed in the connection structure

Abstract

A connection structure includes a dielectric waveguide line and a rectangular waveguide. The dielectric waveguide line transmits a high-frequency signal in a transmission region surrounded by a first conductor layer, a second conductor layer, and two arrays of via hole groups. A coupling window is formed in the second conductor layer. The rectangular waveguide is disposed in such a way that an open end surface of the rectangular waveguide faces the coupling window, and that the transmission direction of the dielectric waveguide line becomes orthogonal to the transmission direction of the rectangular waveguide. A plurality of recesses are formed on a first substrate surface in the vicinity of the coupling window. A recessed conductor layer electrically connected to the first conductor layer is formed on inner wall surfaces of the plurality of recesses.