3-D Beam-Steering MIMO Antenna for On-Body IoT Applications

In this article, a compact 3-D beam-steering MIMO antenna operating at 5.75 GHz is proposed for on-body Internet-of-Things (IoT) applications. The planar antenna comprises a central patch and two concentric annular rings. The theory of spherical modes is used to discuss the beam-steering concept, where the free space measured beam-scanning covers the entire
${xy}$
plane, while a 44° range is realized in
${x{z}}$
and
${y{z}}$
planes. The on-body performance is tested using a multilayer phantom, and the measured peak realized gain is 6.41 dBi. The antenna is characterized by compact size (
$0.77{\lambda }$
), low profile (
$0.03{\lambda }$
), Specific Absorption Rate (SAR) below the established limits, good efficiency, and 3-D beam-steering characteristics while operating in an on-body setup. Therefore, the proposed solution can enable advanced wireless applications like localization and physical layer security in emerging size-constrained on-body IoT devices.