A Linear-to-Circular Polarization Converter with Wide Angular Stability and High Ellipticity for Ka-Band Applications

In this paper, a linear-to-circular polarization converter with wide angular stability and high ellipticity is proposed. The polarization converter works in the transmission mode and is realized by printing periodic cells consisting of split-ring and a metallic strip on both sides of single substrate layer of Diclad 880. In the frequency band: 28.75 – 32.85 GHz, the converter can convert a linearly polarized (LP) incident wave to circularly polarized (CP) wave with very low insertion loss (< 0.65 dB) and axial ratio bandwidth of 13.32%. The unit-cell of the polarization converter possesses an overall size of
$0.0222\lambda_{o}^{3}(\lambda_{o}$
is calculated with respect to center frequency 29.90 GHz). The polarization converter shows an angular stability upto 60° and ellipticity greater than 0.95 in the frequency band: 28.75 – 31.55 GHz under oblique angle incidence. A prototype of 71×71 cells is fabricated and measurement results are in close agreement with simulated ones. The proposed polarization converter can be used for uplink Ka-band fixed satellite service (29.5 – 30.0 GHz) and military satellite communication (30.0 – 31.0 GHz) applications.