Dual wideband high‐efficient reflective linear‐to‐dual‐circular dual‐rotational polarization converter with two complementary twin‐split square‐ring resonators

Abstract

SummaryA 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 at 3.5 GHz is designed and investigated. The unit cell, measuring 8 mm × 8 mm ( 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.