A 2-D Planar Circularly Polarized Van Atta Retrodirective Array With Highly Symmetrical Circular Structure for RCS Enhancement

A 2-D circularly polarized Van Atta array operating in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i>-band is proposed in this letter. Targeting applications with circular array surfaces, a circular deployment is introduced for the first time. Compared to conventional square deployments, this arrangement allows for more array elements and better symmetry. A 24-element Van Atta array phase conjugate network design is completed based on this circular deployment. The network layer is single layered, ensuring that the phase difference between transmission lines is less than 9.45<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula>. It exhibits a good enhancement in the orthogonal direction of monostatic radar cross-section (RCS). The −10 dB beamwidths of the measured normalized monostatic RCS are 106<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ (\varphi =0^{\circ }$</tex-math></inline-formula>) and 94<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ (\varphi =90^{\circ }$</tex-math></inline-formula>) at 9.4 GHz, 109<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ (\varphi =0^{\circ }$</tex-math></inline-formula>) and 105<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ (\varphi =90^{\circ }$</tex-math></inline-formula>) at 9.7 GHz, and 99<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ (\varphi =0^{\circ }$</tex-math></inline-formula>) and 93<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ (\varphi =90^{\circ }$</tex-math></inline-formula>) at 10 GHz, which are in good agreement with the simulated results.