Palm tree coplanar Vivaldi antenna for near field radar application

The Vivaldi antenna is an ultra-wideband device that has high gain and directional radiation pattern. This paper performs a comparison of conventional, regular and exponential edges of a Palm Tree Vivaldi antenna that could operate in L and S band frequencies. The conventional coplanar Vivaldi antenna (C-CVA), regular coplanar Vivaldi antenna (R-CVA), exponential slot edge coplanar Vivaldi antenna (ESE-CVA), regular antipodal Vivaldi antenna (R-AVA) and exponential slot edge antipodal Vivaldi antenna (ESE-AVA), all with the same dimensions, are compared in terms of reflection coefficient and radiation pattern performance. Gain improvement is achieved as 6.22, 7.64, 7.90, 7.92, and 10.74 dB at 3 GHz respectively for R-AVA, ESE-AVA, Convetional - Coplanar Vivaldi Antenna, R-CVA, and ESE-CVA. The number, height, and opening rate of slot edges predispose current distribution and radiation pattern of CVA. Our results show that the exponential slot edge coplanar Vivaldi antenna provides the best gain and derives the best side lobe level, which confirmed the possibility of applying the Palm Tree technique to coplanar Vivaldi antennas, in addition to the antipodal ones, as originally proposed.