Combined twist-bend for very compact interconnections in integrated waveguide subsystems

A novel twist-bend¹ solution is introduced providing a very compact interconnection of two waveguides with 90 degree oriented cross-sections and a perpendicular alignment of their axes. It allows additionally the transformation between different waveguide cross sections connected to the ports without any extra elements. The basic structure consists of a central waveguide section connected via two irises with the interfacing waveguides. This basic twist-bend design serves up to 20% bandwidth with good return loss properties. For larger bandwidth demands transformer sections are associated with the basic structure directly between the irises and connecting waveguides. For example, the extension of this solution with one transformer section at either side of the basic solution provides more than 38dB return loss over 35% bandwidth. Suitable implementations within integrated waveguide structures are introduced, e.g. for the interconnection of E- and H- plane waveguide components of a layer structure or a perpendicular interfacing of a waveguide layer subsystem. For the experimental validation a twist-bend design has been conducted with different waveguide ports (WR34 and WR28) at 28GHz. The good agreement of computed and measured results proves the design approach.