Design of Compact, Broadband, 2-D Wide-Angle Scanning and Low-RCS Phased Array Using Split Ring Structures

We propose a compact wideband phased array with 2-D wide-angle scanning and low radar-cross Section (RCS) performance. The antenna elements comprise two pairs of split-ring (SR) particles and U/E-slot microstrip antennas. Specifically, the SR particles are equivalent to an antiphase metal-plate monopole array in the band to broaden the half-power beamwidth (HPBW) of the microstrip antenna. Meanwhile, the microstrip antenna functions as part of the absorbing structure out of the band to improve the absorption performance. The proposed design provides a simple and universal method to simultaneously manipulate the radiation and scattering characteristics of the microstrip antenna. In particular, an expanded checkerboard
$4\times4$
array is presented and investigated using the proposed elements. Precisely, the array examination is conducted to demonstrate the good performance of a wide operating band from 6.9 to 9.3 GHz (29.6%) and wide-angle scanning up to ±60° in the E-/H-plane, and up to ±65° in the D-plane with a gain fluctuation of less than 3.5 dB. The array also achieves ultra-wideband monostatic RCS reductions in the band from 6.5 to 15 GHz (79%) for the co-polarization, and in the band from 6 to 15 GHz (85.7%) for the cross-polarization of incident waves.