A planar 925-GHz branch line coupler

Conference poster, 2025

Waveguide couplers become increasingly difficult to fabricate at higher terahertz frequencies. In this work, we present a planar branch line coupler with a centre frequency of 925 GHz. The circuit is realized in suspended stripline technology, using a 3-µm silicon-on-insulator membrane. The coupler, embedded via probe transitions in a waveguide system, shows a simulated bandwidth of 18% with return loss and isolation better than 15 dB. The amplitude balance is better than 0.4 dB across this band.