Theoretical Analysis of Beam-Steerable, Broadside-Radiating Huygens Dipole Antenna Arrays and Experimental Verification of an Ultrathin Prototype for Wirelessly Powered IoT Applications

Abstract

The theoretical analysis of beam-steerable, broadside-radiating Huygens dipole antenna arrays (HDAAs) is presented. Linear HDAAs with different numbers of elements are investigated and compared with full-wave simulations. Their attractive performance characteristics for wirelessly powered IoT applications are emphasized. Each Huygens dipole antenna (HDA) is an electrically small, linearly polarized, efficient, unidirectional radiating element. Linear HDAAs are confirmed to achieve high directivity beams in one principle plane and significantly broad beamwidths in the orthogonal principle plane. Very stable gain variation when their main beam is steered is demonstrated. A practical beam-steerable, broadside-radiating, linear HDAA is developed that employs an experimentally-verified HDA and is facilitated by a microstrip power-divider feed network. The entire HDAA design is ultrathin ( $\lambda _{0}/240.87$ ), lying only on a single piece Rogers Duroid $^{TM}~5880$ copper-clad substrate. A proof-of-concept 3-element HDAA prototype excited with a $3\times 3$ Butler matrix centered at 2.45 GHz was designed, fabricated and measured. The measured results, in very good agreement with their simulated values, demonstrate the efficacy of the linear HDAA designs and their potential usefulness for wireless power transfer (WPT) systems dedicated to emerging IoT applications that require power be directed towards terminals in multiple specified directions with broad area coverage at each one.

Keywords

• Antenna arrays
• beam-steering
• Butler matrix
• electrically small antennas
• Huygens dipole antennas
• wireless power transfer (WPT)