A Corrugated Planar-Goubau-Line Termination for Terahertz Waves

The planar Goubau line (PGL) is a promising low-loss metal waveguide for terahertz applications. To enable advanced circuits and multiport measurements based on PGLs, there is a strong need for broadband impedance-matched loads, which can be used to absorb the energy and minimize standing waves in a system. In this work, we propose a termination for PGLs based on an exponentially tapered corrugated line, gradually increasing conductor losses while maintaining small reflections. The corrugation density is high enough to increase conductor losses without requiring an auxiliary low-conductivity material. A 400-
$\mu \text{m}$
-long PGL load was fabricated on a 10-
$\mu \text{m}$
-thick silicon substrate suspended in the air. Simulations of the load show excellent agreement with calibrated reflection measurements in the frequency range 0.5–1.1 THz. Above the cut-off frequency of around 580 GHz, the measured reflections are less than −19 dB, below the noise floor of the characterization setup.