Frequency-Selective Polarization Conversion Metasurface Design Method Based on Parasitic Patch Loading

A novel frequency-selective polarization conversion metasurface (PCM) design method is proposed in this article. Based on the parasitic patch loading technique, several reflective frequency-selective PCMs are designed with simple structure and good polarization conversion performance. The periodic unit is made up of a split ring at the top, a rectangular patch in the middle, and a metallic ground at the bottom. The split ring is used to convert the polarization, and the rectangular patch is used as the parasitic resonator to create an extra coupling path, which introduces an extra polarization conversion pole (PCP) and a zero (PCZ). By introducing two orthogonal patches under the split ring, three PCPs in the band and two PCZs at the edges of the passband can be acquired. Finally, to make the structure simpler and less bulky, a cross-shaped dual-mode rectangular patch is introduced to replace two orthogonal patches, which can also realize three PCPs and two PCZs. The design progress and working principle of the PCM are described and analyzed in detail. To validate the design method, the last PCM is fabricated and measured, containing a 3-dB bandwidth of 4.78–5.24 GHz (9.2%) and two zeros located at 4.7 and 5.3 GHz. This design method can create a PCM that is selective and wideband, and which has a simple structure and is easy to make.