Novel Ultra-Miniaturized Wideband Linear-Circular and Linear-Cross Polarizer Based on Modified Electric Dipole Configuration at THz Regime

This paper showcases a novel reflection wideband linear-circular and linear-cross polarization converter for THz regime applications. The reflective polarizer design uses a thin, low-loss grounded dielectric substrate with a modified electric dipole. This study uses this approach since reflective polarization converters are inherently wideband performance. The suggested layout converts the EM wave from linear to circular polarization in the following frequency ranges: 0.350-0.365 THz, 0.429-0.747 THz, 1.125-1.803 THz, and 1.972-2.010 THz, all with an Axial Ratio (AR) of at least 3dB. On top of that, it can also perform linear-cross polarization from 0.379-0.404 THz, 0.837-1.010 THz, and 1.868-1.935 THz with a minimum Polarization Conversion Ratio (PCR) of 90%. In addition, the reason behind the wideband simultaneous dual-conversion is investigated after the deep analysis of the electric field and surface current distribution profiles of the multiple plasmonic resonances. With an overall volume of
$0.088(\lambda_{L}^{3}/1000)$
, where
$\lambda_{\mathrm{L}}$
is the free-space wavelength and approximately the lowest working frequency, the suggested unitcell is ultra-miniaturized. The proposed design functionality is examined for the TE and TM modes at various oblique angles. The design's unique selling points are the proposed polarizer compactness and, thanks to multiple wideband linear-cross and linear-circular conversions.