Experimental Evaluation of a Subharmonic Detector and Corresponding 1-D Array Concept at 300 GHz

In this paper, we present a tailored antenna system for subharmonic coherent detection at 300 GHz. The antenna is designed to receive the radio frequency (RF) signal at 300 GHz and the local oscillator (LO) signal at 100 GHz from opposite directions. The two signals are mixed and delivered to a detector. To demonstrate the feasibility of our approach, the antenna is packaged with a commercial field-effect transistor (FET) chip via ball-bonding, and its performance is evaluated using a quasi-optical setup. The measurement results confirmed the viability of our antenna design for 300 GHz subharmonic coherent detection. Furthermore, based on this antenna design, we propose a solution for realizing a scalable 1-D subharmonic coherent detector array at 300 GHz. The sparse array concept is utilized here to achieve a large field of view (FoV). To provide sufficient LO power at each detector, an efficient off-chip LO distribution network is designed, and a low-loss near-field coupling approach is presented to transmit the LO power to each detector.