Ultrawideband Array With 70° Scanning Using FSS Superstrate

We present a wideband tightly coupled dipole array (TCDA) with integrated balun and a novel superstrate consisting of printed frequency selective surface (FSS) for wide angle scanning. Although previous TCDAs have had decent scanning performance up to +/-60 degrees, use of dielectric superstrates are usually required, resulting in additional cost and fabrication complexity. In this paper, we replace the bulky dielectric layer(s) with periodic printed elements and yet achieve wide-angle and wideband impedance matching. The proposed approach provides superior performance of 6.1: 1 bandwidth (0.5-3.1 GHz) with VSWR < 3.2 when scanning +/-75 degrees in E plane, +/-70 degrees in D plane and +/-60 degrees in H plane. The FSS, radiating dipoles and feed lines are designed and fabricated on the same vertically oriented printed circuit board, resulting in a low-cost and lightweight structure as compared to other low profile arrays. Measured scanning patterns of a 12x12 prototype are presented, showing good agreement with simulations.