A Novel Comb‐Shaped Serrated High‐Gain Ultra‐Wideband Vivaldi Antenna Loaded With Metasurface

ABSTRACT

Conventional ultra‐wideband Vivaldi antennas usually suffer from limited gain, especially under compact‐size requirements. Existing gain‐enhancement methods, such as enlarged antenna apertures, protruding directors, bulky dielectric lenses, or complex metasurface structures, often increase the antenna size, profile height, or structural complexity. To alleviate these limitations, a compact metasurface‐loaded serrated Vivaldi antenna (MSEVA) is proposed for high‐gain ultra‐wideband applications. The proposed antenna is developed using a step‐by‐step design method. First, comb‐shaped meandering arms are introduced into the conventional Vivaldi antenna (CVA) to form an extended Vivaldi antenna (EVA), which extends the surface‐current path and reduces the lower operating frequency to 2.5 GHz without increasing the antenna size. Then, serrated choke grooves are loaded onto the EVA to form a serrated Vivaldi antenna (SEVA), improving the mid‐ and high‐frequency radiation characteristics. In addition, a non‐resonant metasurface unit is designed and arranged in the end‐fire direction to form a low‐profile metasurface lens. Finally, the metasurface lens is integrated with the SEVA to form the proposed MSEVA, which guides and focuses the radiated wavefront and further enhances the high‐frequency gain. The proposed MSEVA achieves an operating band of 2.5–12 GHz within compact dimensions of 40 mm × 50 mm × 0.762 mm, with simulated and measured peak gains of 12.5 dB and 10.8 dB, respectively. The results show that the proposed antenna effectively improves the gain of compact ultra‐wideband Vivaldi antennas while maintaining compact size, low profile, and structural simplicity.