| Abstrakt: |
In this paper, a transmissive linear-to-circular polarization conversion (LCPC) multibeam metasurface is presented which shows promise for point-to-multipoint transmission in satellite communications under interference conditions. The unit cell consists of four identical metal layers and three dielectric substrates, where each metal layer includes a square ring and a cross-shaped structure. By altering the arm length of the cross-shaped structure, independent control of the phase of x- and y-polarized waves can be achieved. Thus, by keeping the amplitude of the x- and y-polarized waves equal and the phase difference at 90◦ , LCPC is realized. Based on the multibeam superposition theorem, the metasurface array is arranged using four discrete elements with a phase gradient of 90◦ . It can convert linearly polarized (LP) waves into right-handed circularly polarized (RHCP) waves and generate transmitted multibeam at predetermined angles and gain ratios. Three-beam LCPC metasurfaces with equal and unequal gain in the Ka-band (26 to 40 GHz) were demonstrated to validate the proposed unit cell and methods. The equal gain metasurface has an approximate 6% bandwidth for the 3 dB axial ratio (AR) and a 6% bandwidth for the 1 dB realized gain. Furthermore, at the center frequency of 30 GHz, the unequal gain metasurface achieves gains of 22.9 dBi, 19.7 dBi, and 17.3 dBi, respectively, with an AR of less than 2 dB for all three beams. [ABSTRACT FROM AUTHOR] |
