Wideband circular polarizer based on twisted double-layer spiral planar structure

A wideband circular polarizer constructed by using 2×2 array metallic planar spiral structure is proposed. The top and bottom spiral structures are patterned with certain twisted angles with respect to each other along xoy directions. A new class of structure is presented that transmit the incident linearly polarized wave into a circularly polarized wave at microwave frequencies. The impinged wave is converted into a right-handed circularly polarized (RHCP) wave from 14.42 GHz–16.12 GHz. The accumulative axial ratio of Txx, Txy 10% is obtained for circular polarization. Results show that proposed structure possesses substantially good performances, in terms of transmission efficiency and axial ratio bandwidth. The simulated surface current distributions illustrate transformation behavior for linear and circular polarizations. The proposed structure could be useful to design optical devices and polarization control devices.