A Wide-Angle and Fully Polarimetric Retrodirective Array Based on Tri-Polarized Antennas With Pattern Complementation

Abstract

A wide-angle and fully polarimetric Van Atta retrodirective array (RDA) based on tri-polarized antennas is proposed in this article. By leveraging the pattern complementary and polarization orthogonality of three resonant modes including a TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub> monopole-like mode and two orthogonal TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> microstrip patch modes, the RDA could better sense and retrodirect the incident wave with arbitrary polarization over a large field of view. A prototype of the RDA consisting of four tri-polarized antenna elements is designed and fabricated, which works at 5.8 GHz and has a low-profile planar structure with a compact volume of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.93\times 0.56\times 0.059\,\,\lambda _{0}^{3}$ </tex-math></inline-formula> . The simulated and measured monostatic radar cross-section (RCS) results show that, compared with the RDA composed of dual-polarized microstrip patches, this tri-polarized RDA has a significant improvement of the retrodirective angle range for the transverse-magnetic (TM) incident wave. Specifically, for the tri-polarized RDA, the −3 dB monostatic RCS beamwidth is 132°, and the −7 dB monostatic RCS beamwidth can reach 180°; while for the dual-polarized RDA, the −3 and −7 dB monostatic RCS beamwidths are only 52° and 73°, respectively.