Design of a Low-Profile 3:1 Bandwidth Wide-Scan Tightly Coupled Phased Array Antenna

Abstract

A low-profile tightly coupled phased array antenna with the characteristics of 3:1 bandwidth and $\mathbf{\pm 45^{\circ}scan}$ has been proposed in this paper. The array element consists of three layers of Duroid 5880 substrates and a couple of dipole arms. The novelty of the design is the loaded cross-shaped patch which is employed to avoid the common-mode resonance when unbalanced feeding the balanced dipoles. The obtained results confirm that, the array with 7mm spacing can operate from 7 to 21 GHz with VSWR $\leq 2.5$ for 45°scan in both E-and H-planes. The absolute gain of embedded central element pattern is less than 0.6dB compared with the ideal gain, indicating low loss and good efficiency. It is also worth mentioning that, the whole thickness of the antenna is around 4.5mm, which means it is suitable for conformal platforms.