A Compact Low-profile Ultra-wideband Wide-angle Scanning Tightly Coupled Phased Array Antenna

To address the challenges of phased array antennas, which cannot simultaneously achieve low profile, integration, and easy integration while working in ultra-wide band and scanning at large angles, this article designs a compact low-profile tightly-coupled ultra wide band wide-angle scanning phased array antenna. Firstly, a novel microstrip tapered feed balun is designed. This structure can achieve impedance transformation within a wide bandwidth while avoiding loading complex matching networks beneath the antenna. Secondly, metal vias are added to introduce parasitic coupling patches on the basis of the antipodal structure, which can compensate for the shortage of traditional antipodal radiation structures in providing coupling components. Besides, metal strips of specific length are loaded above the antenna element to serve as the wide-angle matching layer, achieving impedance matching from the antenna to free space. Compared with multi-layer dielectric loading, this wide-angle matching layer can share the same dielectric plate with the radiation structure of the antenna. The antenna unit aperture is 14.6 mm (0.29 λ_h) and profile is 27 mm (0.54 λ_h), making its size smaller than existing antennas and realizing a low-profile and lightweight design for the antenna. The simulation results show that the proposed antenna unit can operate in the 2 GHz~6 GHz frequency band, and the active VSWR of the unit is lower than 2.5 when scanned to 60° in the E/H plane. Finally, an 8×8 array composed of antenna elements was fabricated and measured, and the measured results verify the above design.