Ultra-Wideband 90° Waveguide Twist for THz Applications

Abstract

We report on the design, fabrication, and characterization of a novel 90º waveguide step twist with 56% fractional bandwidth. The proposed twist provides 90º field rotation in the frequency range 210-375 GHz. The experimental results are in good agreement with the electromagnetic simulations showing an insertion loss below 0.3 dB and a return loss better than 20 dB over most of the band. The ultra-wideband performance, tolerance to fabrication inaccuracies and compactness makes the proposed design attractive for various mm and sub-millimeter applications. The twist geometry is optimized for simple fabrication through direct milling. Furthermore, the design remains highly compact since both steps are fabricated on a single washer.