Design of a compact high-gain antipodal Vivaldi antenna for UWB applications

This paper presents a compact, ultrawideband (UWB), high-gain antipodal Vivaldi antenna (AVA), which consists of two metal layers and a dielectric substrate. The top metal layer is a radiation fin with a microstrip feeding line, and the bottom metal layer is composed of the same radiation fin with a gradient grounding line and a clover-shaped director. Here, the director composed of three elliptical parasitic patches is employed along the radiation direction to enhance the gain. In order to expand the operating bandwidth and further improve the gain, a comb-like radiation fin with four gradual partially elliptical slots in its outer side is introduced to expand the surface current path and reduce reverse current; therefore, the presented AVA is only 0.75 λ L × 0.30 λ L × 0.007 λ L , where λ L is the wavelength at the lowest operating frequency. Simulation and measurement results show that the proposed AVA possesses a frequency range from 2.2 to 48 GHz. The peak realized gain is over 14.3 dBi at 12 GHz, and the average gain within the entire operating frequency band is over 10.9 dBi. As a result, the proposed AVA is a good candidate for those applications that require UWB, high-gain, and miniaturized antennas.