Linear-to-Circular Polarization Converters With Both E-Field and H-Field Hybrid Responses

This article presents a novel method to design a linear-to-circular polarization converter (LCPC) by using a hybrid array structure, which is composed of meander lines and the split ring resonators (SRRs). The LCPC can respond to both the E-Field and H-Field for the incident wave. When the meander line and the SRR are placed along two orthogonal directions, the composed unit cell would have different electromagnetic response characteristics in the two orthogonal directions. Using this method, two LCPCs working in frequency bands of 6-18 and 2-6 GHz are designed, respectively. The simulated results show that for the LCPC working in 6-18 GHz, the axial ratio (AR) is lower than 3 dB in 6.8-17.32 GHz with a maximum insertion loss (IL) of 1.25 dB. When the angle of incident wave is less than 450, the 3 dB AR bandwidth is 7.87 GHz. For the LCPC working in 2-6 GHz, the AR of entire frequency band is all lower than 3 dB and the maximum IL is 0.82 dB when the incident angle increases to 150. Even at incident angle of 450, the bandwidth with the function of polarization conversion is 3.5 GHz. Experiments on the LCPC (6-18 GHz) are carried out, and the measured results are in agreement with the simulated ones, which proves that the LCPCs design method proposed in this paper is effective and reliable.