A Ferrite-Loaded Ultralow Profile Ultrawideband Tightly Coupled Dipole Array

A dual-polarized ferrite-loaded ultrawideband tightly coupled dipole array (TCDA) with an extremely low profile is presented. A novel ferrite grid with high relative permeability and permittivity characteristic is loaded between the antenna and the ground plane, which expands the low-end of operation bandwidth and reduces the overall profile, simultaneously. An X-shaped frequency selective surface (FSS) is utilized as a special band-stop filter to improve the realized gain at higher frequencies. Meanwhile, the proposed array utilizes a microstrip (MS) to coplanar stripline (CPS) uniplanar double-Y balun to achieve unbalance–balance transformation and impedance matching. A thin meta-surface-based wide-angle impedance matching (MS-WAIM) layer is introduced to improve the beam-scanning ability. Simulated results show that the proposed antenna is able to operate over a 10:1 bandwidth (0.2–2 GHz) with active VSWR < {2, 2.6, 3.4} while scanning up to {broadside, 45°, 60°}, respectively. Most of all, the overall antenna profile is only 62.5 mm ( $0.042\lambda _{\mathrm {L}}$ ) at the lowest operating frequency, which is known to be the thinnest 10:1 ultrawideband array with wide angle scanning (±60° in E- and H-plane) performance. A prototype of $6 \times 8$ array is simulated, fabricated, and measured. Good agreement is achieved between the simulated and measured results.