Design of Low-Profile Polarization-Reconfigurable Van Atta Retrodirective Array

In this letter, a novel polarization-reconfigurable Van Atta retrodirective array (RDA) with wide retrodirective angle is proposed. By controlling the states of p-i-n diodes embedded in the upper patch, the array can switch among linear polarization (LP), left-handed circular polarization (LHCP), and right-handed CP (RHCP). With a single feed port per unit and reused vias, the number of transmission lines is reduced, and dc bias lines require no additional layers, lowering structural complexity and profile. The large retrodirective angle is enabled by the element with a wide half-power beamwidth. Both monostatic and bistatic radar cross section (RCS) results confirm stable retrodirective performance in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane, within a 10-dB impedance bandwidth of 2.15–2.4 GHz for LP and 3-dB axial ratio (AR) bandwidths of 2.23–2.28 and 2.22–2.37 GHz for RHCP and LHCP, respectively. A prototype is fabricated to validate the design, and the measurements agree well with the simulated results. For three polarization states, the monostatic RCS shows a −5-dB beamwidth of at least 84°.