The Banyan Tree Antenna Array

A new wideband, wide-scan array is introduced, called the Banyan Tree Antenna (BTA) array, that employs modular, low-profile, low-cost elements fed directly from standard unbalanced RF interfaces. The elements consist of vertically-integrated, flared metallic fins over a ground plane that are excited by a vertical two conductor unbalanced transmission line. The antenna resembles the bunny-ear or balanced antipodal Vivaldi antenna (BAVA) designs, but most importantly uses metallic shorting posts between the fins and the ground plane that suppress a mid-band catastrophic common-mode resonance that occurs in 2D arrays of balanced radiators fed with unbalanced feeds. This work introduces simple circuit models that describe key performance attributes of the BTA array, leading to unique physical insights and design guidelines. Simulations of infinite single- and dual-polarized BTA arrays have achieved approximately two octaves of bandwidth for VSWR <; 2.2 at broadside and VSWR <; 2.8 at scans out to θ = 45°, while maintaining better than 14 dB polarization purity at θ = 45° in the D-plane.