Metamaterial Enhanced Vivaldi Antenna for Ultra-Wideband Radar Systems

In this study, a compact Vivaldi antenna design is proposed for an ultra-wideband (UWB) radar system operating in the 3.1-4.8 GHz range. Metamaterial unit cells are also designed and implemented to enhance the antenna gain. After designing a compact Vivaldi antenna radiating over 2.68-5.56 GHz, metamaterials were placed along the antenna aperture to investigate their impact on antenna performance. Metamaterial structures with DNG (double-negative) characteristics, operating within the antenna's frequency band, were developed in different sizes. The frequency bands in which the refractive index of the designed unit cell remained negative, as well as the S-parameters, were optimized. A gain improvement of 2.4 dB was achieved over the reference compact Vivaldi antenna, while side-lobe levels were reduced. It was observed that, compared to the reference antenna, the proposed design preserved the desired-band reflection and radiation characteristics.