Design of a Terahertz Beam-Steering Photomixer Array

This paper presents the design of a beam-steering photomixer array for terahertz applications. The design consists of the combination of two identical triple stub circuit (TSC) topologies that allows the impedance tuning and insertion phase control simultaneously. The impedance tuning and insertion phase control is achieved by means of NEMS switches, which change the state of the circuit on each arm, providing a phase difference between of the signals arriving on each antenna, while keeping the input impedance seen on each arm constant. This allows the designed array to provide beam-steering without changing the input impedance seen by the photoconductor, and hence, the efficiency due to impedance mismatch is prevented. The TSC circuits are designed to provide input impedance of 600 Omega and a phase difference of 30 degrees, resulting in a beam-steering of +/- 10 degrees of the radiation pattern of the array. To the best of our knowledge, this is the first-time demonstration of a beam-steering photomixer array using NEMS reconfigurable TSC circuits.