Low-Profile, Electrically Small, Ultrawideband Antenna Enabled With an Inductive Grid Array Metasurface

Abstract

A low-profile, electrically small, ultrawideband (UWB) antenna enabled with a grid array metasurface is presented. The design incorporates a driven dipole, an electric near-field resonant parasitic (NFRP) element, and a grid array structure which operates as an inductive metasurface. The NFRP element is an Egyptian axe dipole (EAD) that is excited by the driven dipole. This combination itself is an electrically small NFRP dipole antenna. In contrast to previous versions, its operation in both its first and third resonant modes is established. The presence of the grid, which consists of identical interconnected rectangular loops, then provides a new dipole mode and facilitates the reduction of the frequency ratio of the NFRP dipole’s modes. The resulting overlap of these three resonant modes yields the UWB operation. The electrically small ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ka</i> = 0.92), low-profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.003\lambda _{0}$ </tex-math></inline-formula> ) antenna exhibits uniform radiation patterns and stable and high radiation efficiency (RE) performance characteristics. The antenna was optimized, fabricated, and tested. The measured results, in good agreement with their simulated values, demonstrate that the antenna yields an ultrawide, 67.7%, −10 dB impedance bandwidth with stable realized gain (RG) values, ~1.6 dBi, and high RE values, RE >77%, over its entire operational bandwidth.