Ultra-Wideband Hexagonal Ring Type Linear-to-Circular Polarization Converter

An ultra-wideband linear-to-circular(LTC) polarization converter(PC) is designed, featuring a hexagonal metal periodic array. The metal rings are placed diagonally, ensuring consistent reflection characteristics for both TE and TM polarized waves. Numerical simulations confirm that, under normal incidence, this converter effectively transforms incident linearly polarized waves into reflected circularly polarized waves within the 18.2-59.4 GHz band, relative axial ratio(AR) bandwidth of 106%), with an AR less than 3 dB. Furthermore, at the central operating frequency of 39 GHz, the LTC PC unit structure is compact, with dimensions of only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.52\lambda_{0}\times 0.52\lambda_{0}\times 0.13\lambda_{0}$</tex>. This miniaturized design significantly enhances its potential for application in integrated K, Ka, and U-band polarization conversion devices. Therefore, this converter provides robust support for achieving efficient and compact polarization conversion and is expected to play a crucial role in related fields.