2-18GHz Wide-Scan Tightly Coupled Dipole Array With Resistive FSS

An ultra-wideband (UWB) tightly coupled dipole array is proposed and investigated in this paper. The antenna element can be directly fed by a 50Ω port without a power divider due to the carefully designed folded Marchand balun with perforated stripline. A resistive frequency-selective surface (FSS) is placed between the dipole and the ground plane to suppress reflected waves, thereby widening the operational bandwidth. Furthermore, a double-layer FSS is designed at the top of the antenna to enhance the array’s scanning performance. Additionally, metallized vias are strategically positioned beneath the ground to connect the two reference grounds of the stripline, enabling the suppression of back radiation. The overall height of the design is 15.0mm (0.90 λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">high</inf>). The proposed antenna achieves a voltage standing wave ratio (VSWR) of less than 3 across a bandwidth of 9.5:1 (1.9-18.0GHz) when scanning up to 60° in the E-plane, and a VSWR of less than 3.1 across a bandwidth of 11.1:1 (1.8-20GHz) when scanning up to 30° in the H-plane. Finally, a 8 × 8 array prototype is presented to verify the performance.