Broadband GCPW-to-Waveguide Transition in Multi-Layer Dielectric Substrates With Modified V-Shaped and Double Patch in 270 GHz Band

This paper proposes a broadband single-ended line-to-waveguide transition that covers the 240–300 GHz band. The transition comprises a tapered grounded coplanar waveguide (GCPW) feed line, inserted from the narrow wall of the waveguide exciting a modified V-shaped patch located at the center of the waveguide. Broadband operation is achieved via multiple resonances of the modified V-shaped patch, a double-stacked rectangular patch, and cavity within the multi-layer substrates. The transition geometries are optimized via electromagnetic simulations using the finite element method. The transition design is successful within fabrication limitations in the terahertz frequency band. Subsequent evaluations of transition performance are conducted through measurements and simulations. Experimental results show a bandwidth below −10 dB for S ₁₁ spanning 71.5 GHz. Furthermore, the measured insertion loss remains consistent at 2.5 dB at the center frequency of 275 GHz.