Four‐hundred gigahertz broadband multi‐branch waveguide coupler

Abstract

Terahertz technology is a hotspot in the current academic research. In this study, a 400 GHz broadband multi‐branch waveguide hybrid coupler is designed, but it is very difficult to fabricate. In order to release the processing difficulty, a modified five‐branch hybrid coupler has also been designed, fabricated and measured. The hybrid coupler consists of five modified branches and has been optimised to a great performance, which increases the operation bandwidth. Compared to the traditional five‐branch hybrid coupler design, this structure has a wider operation bandwidth and the bandwidth is almost the same as traditional seven‐branch hybrid coupler. Based on this model, the performance of the coupler is optimised by HFSS software. The measurement results show good performance that >18 dB return loss ( S 11 ) and isolation ( S 23 ), 90° ± 2° phase difference and 0.3 dB amplitude imbalance are obtained in the frequency range of 380–460 GHz, agreeing well with the simulation results.