Circular polarization

About: Circular polarization is a research topic. Over the lifetime, 15201 publications have been published within this topic receiving 234418 citations.

All-dielectric planar chiral metasurface with gradient geometric phase.

Abstract: Planar optical chirality of a metasurface measures its differential response between left and right circularly polarized (CP) lights and governs the asymmetric transmission of CP lights. In 2D ultra-thin plasmonic structures the circular dichroism is limited to 25% in theory and it requires high absorption loss. Here we propose and numerically demonstrate a planar chiral all-dielectric metasurface that exhibits giant circular dichroism and transmission asymmetry over 0.8 for circularly polarized lights with negligible loss, without bringing in bianisotropy or violating reciprocity. The metasurface consists of arrays of high refractive index germanium Z-shape resonators that break the in-plane mirror symmetry and induce cross-polarization conversion. Furthermore, at the transmission peak of one handedness, the transmitted light is efficiently converted into the opposite circular polarization state, with a designated geometric phase depending on the orientation angle of the optical element. In this way, the optical component sets before and after the metasurface to filter the light of certain circular polarization states are not needed and the metasurface can function under any linear polarization, in contrast to the conventional setup for geometry phase based metasurfaces. Anomalous transmission and two-dimensional holography based on the geometric phase chiral metasurface are numerically demonstrate as proofs of concept.

A Reconfigurable Polarization Converter Using Active Metasurface and Its Application in Horn Antenna

Abstract: This paper proposes a reconfigurable polarization converter based on a p-i-n diode controlled active metasurface (AMS). The AMS consists of a thin dielectric substrate and is tuned by two identical layers of elliptic split rings loaded with p-i-n diodes. The p-i-n diodes are positioned between the split gaps and biased through the interconnected elliptic split rings without extra bias network. The active design achieves conversion from linear to circular polarization when the p-i-n diodes are OFF, whereas no conversion takes place when the diodes are ON. A prototype of the proposed design is fabricated, and the operational characteristics are measured. Both the simulated and the experimental results verify the viability of the design. Subsequently, the converter is applied to a linearly polarized horn antenna as a superstrate, making the polarization of the antenna reconfigurable.

Design of SIW Cavity-Backed Circular-Polarized Antennas Using Two Different Feeding Transitions

Abstract: Two circular-polarized circular patch antennas which have novel feeding structures such as a substrate integrated waveguide (SIW), a cavity-backed resonator and two different feeding transitions, are proposed and experimentally investigated in terms of electrical performances, including reflection coefficients, optimized parameter values, circular polarized antenna gain, axial ratios and radiation patterns. By inserting asymmetrical inductive via arrays into the interface region between the circular patch and SIW feeding structure, it is found that an enhancement of input impedance bandwidth has been achieved. In addition, in order to check the effects of feeding transition types on the electrical performances of the main radiator, two different feeding transitions, namely microstrip-to-SIW and coax-to-SIW, have been studied by considering reflection coefficients, gain, axial ratios and radiation patterns. As a result, it is experimentally proved that a broadband impedance bandwidth of 17.32% and 14.42% under the criteria of less than VSWR 2:1 and 1.5:1, respectively, have been obtained and an RHCP axial ratio of 2.34% with a maximum gain of 7.79 dBic has been accomplished by using the proposed antenna with coax-to-SIW transition operating at the X-band of 10 GHz center frequency.

Broadband circular polarization antenna

Abstract: An efficient, lightweight, broadband antenna, having high quality circular polarization capabilities, is disclosed for use in a variety of applications. In one embodiment, signals are fed to, or received by, an array of electromagnetically coupled patch pairs arranged in sequential rotation by an interconnect network which is coplanar with the coupling patches of the patch pairs. The interconnect network includes phase transmission line means, the lengths of which are preselected to provide the desired phase shifting among the coupling patches. The complexity of the array and the space required are thus reduced. In one described embodiment, two such arrays are employed, each having four patch pairs. The two arrays are arranged in sequential rotation to provide normalization of the circularly polarized transmitted or received beam. In another embodiment, a lightweight material having a dielectric constant less than about 1.5 is employed in the lower resonant cavity and, preferably, in the upper resonant cavity as well.

Analytical method of a multilayered meander-line polarizer plate with normal and oblique plane-wave incidence

Abstract: Simple empirical formulas for perpendicular and parallel polarization susceptances for a meander-line grating plate are given. The numerical results compared favorably with experimental data and published data. Simple transmission-line model in terms of E -type mode and H -type mode for multilayered meander-line polarizer plate is presented for plane wave incidence at normal and oblique angles. Numerical results for design examples are given for practical application.