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Abstract
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A high-efficient linear-to-circular polarization (LP-to-CP) converter with dual-band, dual-rotational-direction reflectivity using a single-layer selective surface (FSS) with a thickness of 0:03λ0 at 3.5 GHz is designed and investigated. The
unit cell, measuring 8 mm 8 mm (0:008λ20 at 3.5 GHz), consists of two dual-slotted square rings, with the outer ring providing two nonadjacent CP bands with two reflective resonances in each. The inner ring, with a 90 rotation and
the ability to create different polarization and phase behavior, obtains two wide bands with high CP quality. Parametric studies and optimal results show an interesting fact that incident x(y)-direction LP wave is effectively converted into right-hand CP, that is, RHCP (left-hand CP, i.e., LHCP) wave at the former band and into LHCP (RHCP) at the later band. Finally, a practical 10 * 10 optimal array is fabricated which offers excellent axial ratio below 2 dB over two wide bandwidths: 3.46 to 5.96 GHz (53%: S and C bands) and 7.8 to 12.2 GHz (44%: X band). The converter is angularly stable over 45 and 30 in the stated bands, respectively. A good agreement between simulation and measurement and essential comparisons with literature are also proposed. The results demonstrate significant potential for different dual-band CP applications with simultaneous isolated uplink and downlink.
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