Ultrawideband Wide-Angle Scanning Dual-Polarized Conformal Array Antenna Using Modular Concave-Down Dipole

This paper presents a novel ultra-wideband wide-angle scanning dual-polarized conformal array antenna using the modular concave-down dipole (CDD). The CDD reduces the complexity of the traditional tightly coupled dipole arrays while maintaining the ultra-wideband performance. The shunt capacitance generated by the concave-down structure reduces the active input impedance, which eliminates the need for a complex impedance-matching network and enables direct feeding through a coaxial cable. The mechanisms of generating loop-mode resonance and common-mode resonance in the dual-polarized CDD array are analyzed. A modified tapered coaxial cable loaded with a low-loss ferrite block is proposed to suppress these resonances and achieve wideband operation of the antenna. The profile of the antenna is 0.067λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> (λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub> is the wavelength at the lowest operating frequency). Leveraging the inherent discontinuity between CDD elements and the compact feed structure, the array is designed in a modular form. Applying the modular approach, a 9 × 9 dual-polarized CDD array is developed and it is conformally mounted on a cylindrical surface with a radius of 80 mm (0.24λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low</sub>). The proposed antenna is capable of beam scanning of ±90° in the conformal plane and ±60° in the non-conformal plane within the frequency band of 0.9-5.0 GHz (5.6:1). Besides promising radiation performance, the proposed design uses the modular approach and provides a flexible solution for different platforms including curved platforms.