Ultra-Thin Uniform Linear Array of Electrically Small Huygens Dipole Antennas

Abstract

A uniform linear array of electrically small Huygens dipole antennas (HDAs) that is realized on a single ultra-thin substrate is presented in this paper. The HDA consists of a pair of near-field resonant parasitic (NFRP) elements and a simple driven antenna element. The NFRP elements are metamaterial-inspired electrically small structures - the Egyptian axe dipole (EAD) and the capacitively loaded loop (CLL). They are excited by an electrically small dipole antenna connected to a 50–Ω source by a twin-line microstrip line. This HDA generates a cardioid radiation pattern with a high realized gain (5.4 dBi) and wide beamwidth (151° in its H-plane). A uniform 1×4 linear array formed with four of these HDAs operating at 2.45 GHz with a center-to-center spacing of 0.45 λo has been developed to achieve higher directivity. The array is excited by a 1-to-4 microstrip feed network. The entire system is realized on a single piece of 0.0042 λo thick PCB substrate. The −10 dB impedance bandwidth covers 70 MHz, from 2.415 to 2.485 GHz. The realized gain is stable over it with a 8.7 dBi peak value. A very broad beamwidth (162°) is realized in the H-plane. The array is an ideal candidate to act as the base station antenna for 5G and beyond wireless power transfer (WPT) applications.