Dual-Polarized Spaceborne Phased Arrays Using Tri-Ridge Evanescent Waveguide Antennas

A full-metal phased array, based on tri-ridge evanescent-fed choke antenna elements, providing simultaneous dual-circular polarizations is proposed in this letter. The full-metal design minimizes power losses at antenna level, reducing system complexity as compared to approaches that rely on the use of dielectric materials and require over-dimensioned arrays for comparable performance. The proposed radiating element enables very low coupling between orthogonally polarized input ports even when scanning. Therefore, this design supports wide-angle scanning in spaceborne phased arrays, while maintaining excellent active matching and active polarization isolation. The proposed concept allows the generation of two independent and simultaneous beams with orthogonal circular polarization from the same apertures. Experimental validation is provided with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text{14 GHz}$</tex-math></inline-formula> prototype scanning up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula>60<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>, for Ku-band low Earth orbit receive payloads.