Demonstration of Sub-Terahertz Coplanar Rectenna using 265 GHz Gyrotron

A 265 GHz rectenna was developed by microfabrication on Si wafer and then assessed using a 265 GHz gyrotron. Coplanar waveguide (CPW) has smaller transmission loss than Microstrip line (MSL) in the higher frequency band and high precision circuit patterns can be fabricated on the same plane by microfabrication. A coplanar slot antenna was designed and a gain of 6.14 dBi was obtained by simulation. The input power was estimated by application of the beam profile measured using an IR camera and the beam output power. As a result, the maximum DC output power and rectenna power density (DC output power per unit area) were 0.5 mW, 0.09 kW/m2 with 266 mV output voltage and $150 \Omega$ DC load. The RF-DC conversion efficiency was obtained as 0.07 % with 644 mW input power. This work is the cutting edge of high-frequency operation in a microwave CPW type rectenna.