An ultrawide‐angle scanning tightly coupled dipole array with double‐layer double‐sided frequency selective surface superstrate

Abstract

In this article, we present an ultrawide-angle scanning tightly coupled dipole array (TCDA). The impedance match issue is a major challenge in the design of ultrawide-angle scanning TCDA. To overcome this issue, we employ a multi-stage wideband balun and design the balun synergistically with the dipole element to improve impedance match performance. A double-layer double-sided (DLDS) superstrate is exploited to further improve scanning performance in the H plane. The capacitance of the DLDS Frequency Selective Surface (FSS) superstrate is used to counteract the inductance at the upper face of the antenna array to improve impedance match at different scanning angles. The DLDS FSS superstrate has similar performance with the equivalent double-layer dielectric superstrate, but with advantages of light weight, low cost, and low cross-polarization level at high frequencies. Consequently, the proposed TCDA has a bandwidth of 2.4:1 (2.1–5 GHz) with VSWR<3, while scanning up to 80° in the E plane, 70° in the H plane, and 75° in the D plane, respectively. A 16 × 16 prototype was fabricated and measured, showing good agreement with the simulated results.