A High-Fidelity Radar Cross Section Analysis and Control Method of Phased Array Based on Impedance Modulation

This article proposes a high-fidelity scattering control method for phased array based on analytical theory, which is applicable to radar cross section (RCS) reduction. Through theoretical derivation, an analytical relationship is established between the array radiation field, antenna-mode scattering field (AM-SF), and structure-mode scattering field (SM-SF). It is demonstrated that, based on analytical formulas, the AM-SF can be modulated into arbitrary scattering patterns using nonuniform termination impedance. The total scattering field (T-SF) is synthesized from AM-SF and SM-SF. Thus, the impedance network, corresponding to the modulated AM-SF, is designed to achieve T-SF control and port matching. Different from previous scattering reduction methods of phased array, the proposed method considers mutual coupling between elements and achieves high-fidelity scattering control while maintaining radiation performance. An eight-element microstrip patch antenna array is designed to validate the proposed method by reducing the RCS to the defined value at the desired angle or angular domain. Specifically, the RCS of the designed array is reduced to −60 dBsm at normal incidence or oblique incidence of −22°, −50 dBsm at oblique incidence of 13°, or to below −40 dBsm across the entire angular domain. There is only slight degradation in radiation gain compared to the reference array, and the scanning range still covers ±60°. The proposed high-fidelity scattering analytical method is well validated numerically and experimentally.