Low-Profile Omnidirectional WIFI Antennas With Pattern Reconfigurability Inspired by Meta-Resonators

A family of low-profile, omnidirectional antennas inspired by metamaterial resonators (meta-resonators) for WIFI applications is proposed. Two novel meta-resonators with an inductive feeding are presented. They can be considered as an LC resonant tank. Arbitrary size miniaturization could be obtained. Three rotated metamaterial unit cells constitute a ring-shaped structure, which generates a horizontally polarized, omnidirectional radiation. A direct microstrip power divider is used to excite them in-phase, achieving a small and low-profile magnetic dipole-like antenna. Their working principles are illustrated in detail by equivalent circuit and current distribution. Two omnidirectional antennas based on different meta-resonators and one pattern-reconfigurable antenna are fabricated and measured, respectively. Their measured -10 dB frequency bandwidth, peak gain, and radiation efficiency are greater than 2.4-2.48 GHz, 1.17 dBi, and 80%, respectively. They demonstrate superior advantages in terms of a miniaturized/low-profile size, simple structure, good bandwidth, and omnidirectional radiation performance, which are well positioned for 2.40 GHz WIFI router or indoor communications.