Ultra-Wideband Lossless Cavity-Backed Vivaldi Antenna

An ultra-wideband, lossless cavity-backed Vivaldi antenna array for flush-mounting applications is proposed. Eigenmode analysis, used to investigate antenna-cavity interaction, has shown that the entire structure may resonate within the band of interest resulting in a significant degradation of antenna performance. A simple approach based on connecting the array's edge elements in E-plane to the cavity walls is utilized to eliminate the deleterious impact of these cavity resonances. The proposed antenna is a 3 × 4 array with three elements in E-plane and four elements in H-plane, fabricated using stacked all-metal printed circuit board technique. Resonant-free behavior with gain better than 5 dBi and VSWR <;2 from 1.5 to 7.5 GHz is obtained. High-quality radiation patterns with sidelobe levels lower than 20 dB over the same bandwidth are also demonstrated. Scan performance of the proposed cavity-backed antenna is investigated in two principal planes and is shown to have similar performance compared to its free-standing counterpart.