Cross-Polarization and Sidelobe Suppression Using Rotational Symmetry Tiling of Identical T-Shaped Subarrays

To concurrently reduce the cross-polarization level (XPL) and the sidelobe level (SLL), two types of T-shaped subarray modules with mirrored ports are designed for a planar polarimetric phased array antenna (PPAA). Combined with the rotational symmetry exact tiling solution (RSETS), the proposed modules can effectively reduce the XPL. Since the modules are irregular, the undesired sidelobes in the 2-D wide-angle scan are also avoided. In this article, the cross-polarization suppression mechanism of the proposed method is explained by decomposing the antenna radiation pattern into even and odd components. To demonstrate the advantages of the proposed two T-shaped modules in the modularity, XPL and SLL, different types of subarrays are compared considering the mutual coupling effect. It is shown that for all candidate RSETSs, the array with the feed probe configuration (FPC) in the image configuration method can always be tiled by the proposed modules. Based on this, the process of searching the optimal RSETS on the same array antenna is presented. The effectiveness of the proposed method is verified by different numerical experiments and comparisons with the image configuration method using a 2 x 2-element subarray.