Design of low profile antipodal Vivaldi antenna for ultra-wideband near-field imaging

In this paper, the design of a low profile circularly tapered antipodal Vivaldi antenna for array-based UWB near-field imaging is presented. The proposed circular termination at the end of radiating flare and optimization of the feeding transition result in extension of the operational bandwidth and improvement of antenna impulse response. The antenna design with dimensions of 45×48.5 mm achieves satisfactory impedance matching and radiation across the frequency band from 2.7 to 35 GHz with more than 170% fractional bandwidth. Both SMA and 2.4 mm connectors are tested with the manufactured antenna in order to confirm its UWB performances.