Low-Profile Multifunctional Pattern Reconfigurable Antenna Using Periodic Capacitor-Loaded Surface for 5G and Beyond

Abstract

This article describes a novel low-profile multifunctional pattern reconfigurable antenna using the periodic capacitor-loaded surface for 5G and beyond applications. A miniaturized periodic surface structure is first proposed using the shunt-loaded capacitor, which is studied by equivalent circuit models. A quarter-wavelength T-shaped director slot is etched on the edge of the ground, which leads to a tilted radiation pattern. By switching the ON-/OFF-states of p-i-n diodes embedded in the director slots, the main direction of the beam of the proposed antenna can be tuned among +35°, 0°, and −35°. To verify the design concept, a multifunctional pattern reconfigurable metamaterial-inspired antenna with a low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.05~\lambda _{0}$ </tex-math></inline-formula> is fabricated and measured. The measured overlapping bandwidth for the eight radiation modes is 3.10–3.85 GHz (21.6%), well covering the 5G-N78 band. The port isolation between the two polarizations in eight modes is higher than 20 dB. The proposed reconfigurable metamaterial-inspired antenna shows the merits of low profile, wide bandwidth, high port isolation, low cost, multifunctional pattern reconfigurable capability, and easy fabrication for 5G and other sub-6 GHz applications.