Conformal Parallel Plate Waveguide Polarizer Integrated in a Geodesic Lens Antenna
Freysteinn Vidar Vidarsson, Oskar Zetterström, Astrid Algaba Brazález, Nelson J. G. Fonseca, Martin Johansson, Lars Manholm, Óscar Quevedo-Teruel
Abstract
Here, we propose a low-profile polarizing technique integrated in a parallel plate waveguide (PPW) configuration, compatible with fully metallic geodesic lens antennas. The geodesic shape of the antenna is chosen to resemble the operation of a Luneburg lens. The lens is fed with 11 waveguide ports with 10° separation producing 11 switchable beams in an angular range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm \mathrm{50}^{\circ }$ </tex-math></inline-formula> . Two metallic polarizing screens are loaded into the aperture of the antenna to rotate the electric field from a vertical linear polarization, which is the polarization of the transverse electromagnetic (TEM) mode supported in the lens, to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+ \mathrm{45}^{\circ }$ </tex-math></inline-formula> linear polarization. Since the polarizing unit cells are integrated into the aperture of the antenna, the final design is compact. In addition, the size of the polarizing unit cells is about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.55\lambda $ </tex-math></inline-formula> at the central frequency of operation making the antenna suitable to produce an array formed of stacked lenses. A prototype of the antenna in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{K}_{\text {a}}$ </tex-math></inline-formula> -band was manufactured and tested, verifying the performance obtained in simulations.