Low-Profile, Lightweight, Ultra-Wideband Tightly Coupled Dipole Arrays Loaded With Split Rings

An ultra-wideband and wide-scanning tightly coupled dipole array with low-profile height and lightweight is presented. A novel split ring (SR) printed on planar single-layer printed circuit board is designed and loaded on each element of the proposed array to replace the conventional wide-angle impedance matching (WAIM) superstrates, which usually consist of dielectric slabs. Consequently, the array achieves a 7.2:1 impedance bandwidth (0.3-2.15 GHz) while scanning up to 70° in the E-plane and 45° in the H-plane for active VSWR <; 3.0. Larger scanning angles of 75° in the E-plane and 60° in the H-plane over the same operating frequency are obtained for a relaxed impedance matching criterion (active VSWR <; 4.1). In a dual-polarized configuration based on modified SR-loadings, the cross-polarization level in the D-plane maintains below -20 and -15 dB for 45° and 60° scanning, respectively. The total thickness of the dual-polarized array is only 0.47 wavelength at the highest operating frequency. An 8 ×8 prototype array weighing only 4.3 kg (including an aluminum ground plane of 2.3 kg) was fabricated. The measured results are in good agreement with the simulated results.