WAVEGUIDE TRANSITIONS FOR THE TERAHERTZ RANGE

Abstract

In the antenna-feeder paths of the terahertz (THz) range, waveguides of increased cross sections, the so-called "oversized waveguides", have found wide application. This term refers to a waveguide whose transverse dimensions are much greater than the length of the propagating wave in it. The peculiarity of such waveguides is the possibility of propagation of waves of higher types in it, which are excited on the homogeneities of this waveguide and can have a significant impact on the operation of the entire antenna-feeder path. This can lead to resonances at the transcendental section of the oversized waveguide. This phenomenon has been studied in detail in quasi-optical paths for radio relay systems. Indeed, since the inputs and outputs of most active components of microwave transceiver systems use a standard single-mode waveguide, cone junctions, or as they are often called wave type converters, are used to excite an oversized waveguide.

A wave type converter for excitation of an oversized waveguide is an important element of a quasi-optical antenna-feeder path, since it allows matching the output (input) channel of the active components of the transceiver device (generators, amplifiers, etc.) with the quasi-optical path, which are usually made on base of waveguides of the main section. At the same time, the design of almost any type of transducers is based on the formation of a field distribution, the transverse structure of which coincides with the field of the working wave of the oversized waveguide, for example, when the field structure of the waveguide of the main section is smoothly transformed into the working type of the wave of the oversized waveguide.

In this paper, waveguide transitions for the terahertz range are considered, which provide minimal conversion losses when joining waveguides with different cross sections. A metal-dielectric waveguide of square cross section is used as the main waveguide.