Dual-Linear Polarized Phased Array With 9:1 Bandwidth and 60° Scanning Off Broadside

Abstract

We present, for the first time, a novel dual-linear polarized tightly coupled dipole array with integrated balun operating across a 9:1 bandwidth, from 2 to 18 GHz. This dual-linear polarized array employs a tightly coupled dipole topology and scans down to 60° from boresight. The overall geometry consists of cross-located tightly coupled dipoles integrated with a folded Marchand balun that serves as an impedance transformer to achieve a wideband feeding network. Notably, the traditional dielectric superstrate is replaced with double layers of frequency selective surfaces to enable scanning down to 60° in both E-, H-, and diagonal (D)-planes across the entire band. The design achieves VSWR <; 3 across 2-18 GHz at broadside. This dual-polarized array is also demonstrated to have a good polarization isolation of -20 dB for most of the band. The array's total height is less than 12 mm (λlow/10). The design is validated through fabrication and testing of an 11 × 11 prototype. The measurements of this prototype are presented and are in good agreement with simulations.