Asymmetric chiral metamaterial circular polarizer based on four U-shaped split ring resonators

Abstract

An asymmetric chiral metamaterial structure is constructed by using four double-layered U-shaped split ring resonators, which are each rotated by 90° with respect to their neighbors. The peculiarity of the suggested design is that the sizes of the electrically and magnetically excited rings are different, which allows for equalizing the orthogonal components of the electric field at the output interface with a 90° phase difference when the periodic structure is illuminated by an x-polarized wave. As a result, left-hand circular polarization and right-hand circular polarization are obtained in transmission at 5.1 GHz and 6.4 GHz, respectively. The experiment results are in good agreement with the numerical results.

Ultra-Compact Multi-Band Chiral Metamaterial Circular Polarizer Based on Triple Twisted Split-Ring Resonator

“…where t +x , t −x , t +y and t −y are the four RCP and LCP transmission coefficients from the linear to circular polarization conversion, which indicates the capability of the CMM to convert an EM wave with linear to circular polarization [30][31][32][33][34]. Moreover, the substantially large or small difference (PER) between the RCP and LCP waves can be calculated as:…”

“…The CMM slab is placed in the middle of the horn antennas. Both antennas own VSWR < 2 and face each other with a distance of 1 m over a wide frequency range of 5 to 17 GHz to eliminate near-field effect [30]. When a broadband plane EM wave with y-polarization is normally impinged on the designed CMM slab propagating along −z direction, the transmission coefficients of co-polarization t yy and cross-polarization t xy are obtained.…”

“…Later, a photonic CMM composed of twisted split-ring-resonator was proposed, where a significant circular polarized wave with different rotation directions at two distinct resonances was observed [20]. Then, four U-shaped split ring structures with different sizes [30], planar bi-layer spiral structures [31,32], twisted split ring resonators (SRRs) with double rings [33], Hilbert-shaped structure and other novel asymmetric CMMs [34][35][36][37][38] have afterwards been intensively reported. Among them, nearly all these CMMs could be available to tailor the cross coupling between electric and magnetic fields, resulting in a giant CD effect for circular polarization at resonances [39].…”

Application of Chiral Layers and Metamaterials for the Reduction of Radar Cross Section

“…During the past several years, chiral metamaterials as a kind of artificial materials has attracted an enormous amount of interest that could be used to achieve many customized functionalities, such as the negative refraction and giant optical activity [10][11][12][13][14][15][16][17][18][19][20], and many other applications [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. The constitutive equations for chiral media assuming a time harmonic dependence e jωt are [1]:…”

Dual-Band Circular Polarizer and Asymmetric Spectrum Filter Using Ultrathin Compact Chiral Metamaterial

“…The unusual polarization functionalities and chirality not found in natural medium arise from the magneto-electric cross coupling of chiral structures due to their bianisotropy and lack of any mirror symmetry. After the extensive theoretical or numerical studies, and experimental realizations, there have been many efforts tending toward the practical applications of the CMMs in manipulating the polarization states of EM wave [16][17][18][19][20][21][22][23][24][25][26][27][28][29], polarization spectral filtering [30], improving the gain and axial ratio of circularly polarized antennas [31], subwavelength focusing and imaging [32], as well as microwave absorbers [33]. A set of circular polarizers [16][17][18][19][20][21][22][23][24] and pure linear polarization rotators [25][26][27][28][29] have been intensively reported.…”