Method to Estimate Antenna Mode Radar Cross Section of Large-Scale Array Antennas

A method to estimate the antenna mode radar cross section (AM-RCS) of a large-scale array antenna is proposed. The scattering pattern multiplication method (SPMM) indicates that the antenna mode scattering field of an array antenna can be obtained by the superposition of all the element mode scattering patterns (EMSPs). However, the mutual coupling and edge effects are ignored in the SPMM, which degrades the accuracy. The active element mode scattering pattern (AEMSP) is the EMSP affected by the mutual coupling and edge effects, which is used to improve the SPMM. Furthermore, based on the assumption that the interior elements of a large-scale array antenna have the same array environment as the middle element of its subarray, the proposed method can deduce the AM-RCS of a large-scale array antenna from the subarray. In addition, the accuracy of the proposed method can be improved with the increase of the subarray size. For verifying the generality and reliability, the proposed method is used to estimate the co-polarization AM-RCS of a 21-element microstrip linear array and $15\times13$ Vivaldi planar array. Compared with the reference method, the proposed method has a low calculated error and saves a lot of memory requirement.