A 2-18-GHz, Ultra-Wideband and Cylindrically Conformal Phased Array Using Tightly Coupled Dipole Element with Low Profile and Low SCS

In this paper, an ultra-wideband, cylindrically conformal phased array antenna with a ultra-wide impedance bandwidth (2-18-GHz) is proposed. This array is composed of the tightly coupled dipole elements. It has an array profile lower than 0.06 lambda(low), where lambda(low) is the wavelength at the lowest in-band frequency (2 GHz). Low scattering cross section (SCS) characteristic within the operating bands is also achieved. The integrated capacitance component is added into the Marchand balun for improving the bandwidth and reducing the profile height. Then, a multi-layer meta-surface (MS) structure is added to improve the wide-scanning impedance matching inside +/- 60 degrees volume. By adding the slots on the multi-layer MS, the inverting phase response (0 degrees/180 degrees) for the cross-polarized incident wave is achieved, so that the ultra-wideband SCS reduction is obtained. To certify the correction of this design, a prototype array is built and measured.