Ultralow Scattering Design of Wideband Conformal Arrays Based on Optimally Loaded Resistors

Abstract

A novel approach based on the use of a resistor-loaded meta-surface (RL-MS) with optimized resistor values is proposed for scattering control in wideband conformal phased arrays. Specifically, the resistance of the loaded resistor in each RL-MS element is varied. As a result, the proposed RL-MS structure not only absorbs incident EM waves but also scatters the remainders away from threatening directions. To accelerate the design process, the scattering matrix approach is used to calculate the scattering patterns efficiently. Proper resistor element distribution can be achieved by optimizing the scattering characteristics. The RL-MS structure is used as the cover layer of a wideband conformal array. By loading the optimized resistors, scattering in the proposed array is reduced to a relatively low level with little degradation of radiation performances. The final designed array achieves 3:1 impedance bandwidth with scanning up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 60^{\circ }/\pm 45^{\circ }$ </tex-math></inline-formula> in the E-/H-plane. Remarkably, a monostatic scattering reduction of approximately 30 dB is observed throughout the X-band in the simulated results of the optimized array. To demonstrate the effectiveness of this design, prototype arrays are fabricated and measured. The measured results are in reasonable agreement with the simulated results.