Mm-Wave Beam Steering Antenna Arrays Using Microfluidically Reconfigurable Beamforming Networks

Abstract

A microfluidically reconfigurable beamforming network is introduced for beam steering mm-wave antenna arrays. The beamforming network consists of a selectively metallized plate (SMP) that is encapsulated within a microfluidic channel in close proximity to multiple microstrip lines. Metallization traces of the SMP capacitively loads the microstrip lines to realize multiple slow-wave phase shifters. Varying the position of SMP over the lines creates variable phase shifts of the device. Strategically designing the SMP traces on each microstrip line leads to progressive phase shifting, resulting in operation with a single actuator. The manuscript presents a circuit model to facilitate the design of the beamforming network and presents experimental verification with a four-element antenna array operating at 28.5 GHz. The array exhibits continuous beam steering capability within $\pm {30}^{\circ }$ when its SMP is actuated within its 100 to +100 $\mu$ m displacement range. The beam steering speed from $-{30}^{\circ }$ to $+{30}^{\circ }$ is 75 ms. The realized gain is 5.6 dBi at broadside and 6.8 dBi at ${30}^{\circ }$ scan angle corresponding to a radiation efficiency of 64% (including all losses in the system). The device is expected to handle 10 W of continuous RF power