Broadband linear polarization converter with stable bandwidth at large incident angles achieved through a...

This work introduces a magnetically coupled metasurface to create a broadband linear polarization converter with stable bandwidth (BW) at large incident angles. Each unit cell of the metasurface is a magnetic resonator comprising an I-shaped structure, a pair of cut wires, and six vertical vias. The use of vias can effectively minimize the size of the periodic elements (period of 0.13λ₀ and thickness of0.069λ₀, where λ₀ is the free-space wavelength at 7.94 GHz), thus broadening the angular range over which effective polarization conversion is attained. Under normal incidence, the proposed design achieves a 90% polarization conversion ratio (PCR) BW ranging from 7.94 to 12.76 GHz, with a 46.6% fractional BW. This superior polarization conversion performance is maintained at incident angles up to 45°, with a 90% PCR BW variation of only 2.9%, and at incident angles up to 53°, with an 80% PCR BW variation of only 1%. Moreover, equivalent circuit models (ECMs) are developed to analyze the stability of polarization conversion under oblique incidence. The experimental results are in good agreement with the simulation results obtained using commercial software and ECMs.