Waveguide-to-planar circuit transition for millimetre-wave detectors

TL;DR

This paper introduces a simplified waveguide-to-planar circuit transition using a unilateral finline taper, reducing complexity and insertion loss for millimeter-wave detectors at 90 GHz.

Contribution

It proposes a novel direct transition design that avoids antipodal finline tapers, simplifying fabrication and improving performance.

Findings

Designs demonstrated at 90 GHz for superconducting detectors

Scale-model measurements conducted at 15 GHz

Reduced insertion loss and chip length

Abstract

We present a novel design of a waveguide to microstrip or coplanar waveguide transition using a unilateral finline taper. The transition from the unilateral finline mode to the TEM microstrip mode is done directly, avoiding the antipodal finline tapers that have commonly been employed. This results in significant simplification of the design and fabrication, and shortening of the chip length, thereby reducing insertion loss. In this paper we shall present designs at 90 GHz that can be employed in superconducting tunnel junction mixers or Transition Edge Sensor bolometers, and scale-model measurements at 15 GHz.