Broadband waveplate operation by orthotropic metasurface reflector

Abstract

We present an anisotropic metasurface offering a simultaneous linear to cross-polarization conversion and linear to circular polarization conversion operations on large bandwidths of microwave frequencies. The proposed orthotropic structure consists of metallic bow tie shaped patches with embedded circular patches enabling diagonal structure symmetry. We demonstrate through numerical simulations and experiments that the metasurface can be used as a high efficiency linear to cross-polarization reflective converter within the two broad frequency bands of 7.48–10.55 GHz and 18.47–19.52 GHz with a polarization conversion ratio above 90%. Simultaneously, the designed metasurface acts as a circular polarizer for linearly polarized incident waves in triple frequency bands of 6.10–7.46 GHz, 10.55–18.42 GHz, and 19.60–22.39 GHz with an axial ratio below the 3 dB threshold. To the best of our knowledge, the second band from 10.55 to 18.42 GHz of circular polarization conversion “has the highest reported (to date) bandwidth of 54.3% for an axial ratio below 3 dB.” The designed metasurface remains angular stable up to 75° over most of the part of the above-mentioned operating bands for both transverse-electric and transverse-magnetic polarized wave incidences.

Anti-reflecting metasurface for broadband polarization independent absorption at Ku band frequencies

“…The antireflection properties that contribute to the overall absorption characteristics relies on induced currents on individual unitcells. Figure 1 a shows four adjacent unit cells inside a conventional polarization conversion metasurface 48 , 49 . Here, each unit cell supports rotational currents in response to the incident electric fields.…”

“…Recently, resonance based chiral metasurfaces are proposed to transform polarization of electromagnetic waves. A microwave metasurface is designed to offer a simultaneous linear to cross-polarization conversion and linear to circular polarization conversion 48 . The bow-tie shaped unit cell element design supports large operational bandwidth (for polarization conversion of reflected fields) at microwave frequencies.…”

A compact single‐layer reflective metasurface for high‐efficiency polarisation conversion applications in C and X bands

“…The lower frequency shift can be elucidated by applying the resonance equation [53], f r = 1=2π ffi ffi ffi ffi ffi ffi ffi LC p…”

“…The lower frequency shift can be elucidated by applying the resonance equation [53], f r = $$1/2\pi \sqrt{LC}$$, where f r represents the resonance frequency, and L and C denote the inductance and capacitance, respectively. Scaling the proposed assembly to 1.25 increases both L and C for the PC, leading to a shift in the resonance to a lower frequency according to the resonance equation.…”

A conformal beam splitter with polarization transformation operation

“…To achieve resonance “n” should be considered 1,3,5 and so on. Here, the proposed FSS works at 5.87 GHz (mode 1, n = 1), and 17.95 GHz (Mode 3, n = 3) 18 . The beam splitting operation with polarization transformation functionality specifically depends on the anisotropy and geometrical configuration of the unit cell structure 19 , 20 .…”