Low-Profile Tightly Coupled Dipole Array Loaded with Double-Layer Split Rings

A novel split ring (SR) wide-angle impedance matching (WAIM) printed on a double-layer PCB was designed to replace the dielectric slabs WAIM or frequency selective surface (FSS) WAIM with high profile. The proposed WAIM is designed together with tightly coupled dipole array (TCDA). Consequently, TCDA loaded with the proposed double-layer SR achieves a impedance bandwidth of 8.5:1(2.12-18 GHz ) with active VSWR＜3.2 at broadside; while scanning up to {60°,75°}in E-plane, a bandwidth of {8.2:1 (2.17-17.91GHz) , 6.1:1(2.91-17.43GHz)} is achieved; while scanning up to 45°in H-plane, a bandwidth of 6.8:1(2.55-16.77GHz) is achieved. Compared to the FSS loaded TCDA with a 0.078λ
l
profile, the double layer SR loaded TCDA can ensure wideband, wide-angle scanning capability with a lower profile of 0.058λ
l
(λ
l
is the free-space wavelength at the lowest frequency).