Near Field Sensing Applications with Tunable Beam Millimeter Wave Antenna Sensors in an All-in-One Chip Design

Abstract

In this paper, a single-band beam control antenna is designed with a parallel coupler to realize a microstrip patch antenna passive wireless sensor in the form of a chip. It has a phase shift characteristic of the antenna radiation direction in the positive and negative directions. The antenna includes an orthogonal direction coupler design with a 90° parallel coupler in phase using a special structure that allows the whole chip area to be miniaturized while allowing the main beam angle to have a directivity function. The coupler is designed for the 28 GHz millimeter wave band. After feeding the patch antenna at the output port of the coupler and simultaneously feeding the excitation at the input port, the beam phase changes to +45° and +135° with a phase difference of 90°. The designed antenna size is 1160 μm × 790 μm, and the overall IC size is 1.2 mm × 1.2 mm. The power density simulation shows that the maximum power density is only 0.00797 W/kg for a 1 cm2 human sampling area, which means that the antenna sensor is suitable for use on human surfaces.