Design of S/X-Band Dual-Loop Shared-Aperture 2×2 Array Antenna

Abstract

This article proposes the S/X band dual-loop shared-aperture 2 × 2 array antenna, which is constructed using a unit-cell having one Sband element stacked on 3 × 3 X-band elements. The unit-cell employs a coupled-fed dual-loop structure with a direct-feed pin on the upper loop to obtain the broadband matching characteristics and low manufacturing error. This radar configuration has the advantages of easy installation and low cost. In addition, the thin loop structure of the upper layer S-band element is optimized so that the S-band element has electromagnetic (EM) transparent characteristics in the X-band. The extended via cavity wall is also applied outside the nine Xband elements to block the mutual coupling effect among the X-band elements. To confirm the feasibility of the proposed array antenna, the beamforming performance and active reflection coefficient (ARC) characteristics of the fabricated array are examined in the S/X band.