Broadband Holographic Mode Synthesis Between Adjacent Resonances for a Low-Profile Thin-Microstrip Antenna-Fed Metasurface

This paper proposes a novel technique for designing a broadside-radiating, low-profile grounded-dipole antenna—referred to here as a low-profile thin-microstrip antenna—that achieves wide bandwidth by using characteristic mode analysis and a holographic metasurface. Initially, a 3×3 subwavelength patch array is stacked on a grounded dipole antenna to achieve wideband impedance matching. There are two resonant frequencies: one corresponding to the thin-microstrip and the other to the patch array. To separate these resonant frequencies, a thin-microstrip-oriented slot is implemented in the center patch of the array. The deteriorated impedance matching at the center of the bandwidth (14 GHz) caused by the center-patch-slot is addressed by integrating a holographic metasurface around the patch array, which introduces an additional surface-wave propagating mode. The simulated and measured -10 dB impedance bandwidths are 25.5% and 24.9%, respectively, with an ultra-thin profile of 0.025λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at the center frequency.