Wideband Superstrate-Loaded Metasurface-Based Multifunctional Polarization Converters
Soumendu Ghosh, Patinavalasa Megh Sainadh, Abhishek Sarkhel, Saptarshi Ghosh
Abstract
In this letter, two different configurations of a multifunctional polarizer are designed in a compact geometry for simultaneous linear-to-circular (LP-to-CP) and linear-to-linear (LP-to-LP) polarization conversion with enhanced bandwidths. The metasurface unit cell consists of an anisotropic geometry printed on a metal-backed dielectric substrate, while a superstrate is placed above the pattern to aid in the bandwidth enhancement. The configuration-1 exhibits simultaneous wideband LP-to-LP conversion in the range of 4.52 GHz to 4.76 GHz, 7.94 GHz to 15.95 GHz, as well as wideband LP-to-CP conversion over 4.90 GHz to 7.41 GHz, 16.12 GHz to 16.97 GHz. Subsequently, the characteristic mode analysis is utilized to modify the design topology, and Configuration-2 is realized with multi-band LP-to-LP conversion at 4.73 GHz to 5.09 GHz, 6.58 GHz to 7.66 GHz, and simultaneous wideband LP-to-CP conversion over 5.36 GHz to 6.12 GHz, 8.08 GHz to 15.02 GHz. Both designs have small footprints (having unit cell dimensions of 0.143λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.143λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>, λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> being the lowest operating wavelength) and demonstrate angularly stable characteristics up to 50° incidence. The structures are fabricated and the experimental responses are in good agreement with the simulations. Later, two checkerboards (CB-1 and CB-2) using two different metasurface configurations are designed, leveraging their phase gradient responses for low radar cross-section (RCS) applications, depicting >10 dB RCS reduction bandwidths over 4.5 GHz to 4.8 GHz, 7.9 GHz to 16.1 GHz for CB-1, and 4.8 GHz to 5.3 GHz, 7.0 GHz to 7.7 GHz for CB-2, respectively.