Design of Low-Frequency Tightly Coupled Dipole Array With Transformer Balun

Tightly Coupled Dipole Array(TCDA) is a new type of radar antenna with UWB performance and low profile, but relevant designs focus on microwave frequency band. This article presents a TCPA working in 110-520MHz. Each array element is protected from the effect of the common mode resonance by the shorting posts, and excited by the co-designed integrated transformer Balun, which works as the wide-band impedance matching network and provides a balanced feeding. For wide-angle scanning, a printed Frequency Selected Surface(FSS) is used in place of the bulky dielectric superstrates. The final array achieves a low profile(
$0.1 \lambda_{Low}$
) and superior performance of 5:1 bandwidth with VSWR<2.5 when scanning ±50° in
$E$
plane and ±40° in
$H$
plane.