MEMS Phase Shifters for THz Beam-Scanning: Demonstration with a 500-600 GHz Leaky-Wave Phased Array

Beam-scanning capabilities for space-borne submillimeter-wave spectrometers are critical for instrument calibration and field-of-view mapping. However, the lack of low-loss waveguide-integrated phase shifters above 500 GHz has been a significant challenge for the realization of THz phased array antennas. Recently developed MEMS-actuated phase shifters have emerged as promising candidates, initiallydemonstrating a 145◦ phase shift. As a first demonstration of the efficacy of these phase shifters for electronic beam-steering, we present the design, fabrication, and characterization of a linear, near-Nyquist sampled, 4x1-element phased array operating from 500-600 GHz. The array element is a silicon micro-machined leaky-wave feed based on a Fabry-Perot cavity to enhance directivity and reduce grating lobes while achieving the bandwidth requirements with minimal scan loss. It is shown, through measurement, that this antenna feed is suitable for use in larger 8x1-element arrays for applications that require moderate gain (20 dBi) and scanning (±20◦) with a fan beam. Furthermore, we present measurement results of a secondgeneration of MEMS phase shifters with an increased measured phase shift up to 350◦ . A full 360◦ phase-wrapping capability is desired as this will enable high-gain lens-scanning phased arrays that can be used for future submillimeter-wave spectrometers.