Xiaofan Yang

Bio: Xiaofan Yang is an academic researcher. The author has contributed to research in topics: Polarization rotator & Antenna (radio). The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

A Broadband Ultra-Thin Polarization Rotator Using Periodically Loaded Parallel Strip-Lines

Abstract: A polarization rotator based on loaded parallel strip-lines is theoretically and experimentally investigated. The unit cells are short-stub loaded parallel strip-lines. The arrays on the front and back layers are rotated by 90° to each other. By loading the stubs, good coupling between the two layers is obtained. Such a structural rotation along with the loading stubs allow the $y$ -polarized wave to be converted to $x$ -polarized wave through field coupling. A broad transmission bandwidth of 30% (86-116 GHz) by using the proposed structure has been reached. In addition, the PTFE substrate is only 0.25 mm thick, which is less than $0.1\lambda $ at 86 GHz. Such a thickness allows the polarization rotator to be easily mounted on antenna radomes. The fabricated prototype demonstrates good agreement between simulation and measurement results.

Broadband Reflective Polarization Rotator Built on Single Substrate

Abstract: A broadband polarization rotator built on single substrate is presented in this work. The device is designed for operation in the K and Ka bands. A slant array is used to achieve polarization rotation by 90° in a reflective manner. Broadband has been obtained, with the operation frequency range covering 15–45 GHz for 3 dB criteria, which is almost 100% fractional bandwidth. In addition, the insertion loss is less than 0.3 dB over a moderate broad incident angle from 0°–20°. Furthermore, the polarization conversion ratio can be as high as 0.95. By using a bi-static method, the fabricated prototype is measured, and the measured results demonstrate satisfactory agreement with the simulation ones. In comparison with other reflective designs in the literature, this design provides good bandwidth as well as polarization conversion ratio. Miniaturization can be investigated to increase the angular stability.

Dual-band polarization conversions and optical diode based on bilayer T-shaped metamaterial

Abstract: • The work achieved x- to -y / y- to -x conversions at 106 / 163 THzfor +z propagation. • The incident waves are blocked for – z propagation. • The T xy and T yx are increased to 0.74 and 0.75 with the PCR s reach up to nearly 100%. In this work, we propose a dual-band optical diode based on a bilayer T -shaped metamaterial. This optical diode can conveniently convert the x -polarized wave to y -polarized one at about 106 THz and convert the y -polarized to x -polarized wave at around 163 THz when linearly polarized waves impinge on the sample under a forward normal incidence (+z direction). The dual-band polarization conversion ratios can reach up to 99.9 % and 99.6 % at 106 and 163 THz, respectively. In addition, the bi-layer metamaterial works as an optical diode located around the frequencies 106 and 163 THz, i.e. the x - and y -polarized plane waves can pass through the metamaterial in the forward direction, however, they are prevented from backward. The maximum asymmetric transmission parameters are 0.46 and 0.50. At last, both the ratios and bandwidth of dual-band cross-polarization conversion can be conveniently manipulated by the rotation angle θ . This proposed dual-band polarization conversions and optical diode may have promising applications in optical nano-devices, such as optical switches and polarization converters.

Demonstration Of Wideband Polarization Conversion Using Novel Reflective Metasurfaces

Abstract: This paper presents the study of a reflection-type polarization rotator realized by a single layer metasurface deposited on a metallic ground plane. The metasurface consists of an array of three planar metal patches with two neighboring Plasmonic resonant frequencies. The structure is designed, simulated, and the fabricated prototype is experimentally characterized. It converts indifferently, a linearly polarized (CoPol) plane wave into an orthogonal cross-polarization (X-Pol). A high Polarization Conversion Ratio, PCR above 80% is achieved over a bandwidth (2.8 GHz) from 7.5 GHz to 10.3 GHz and a relative insensitivity to the incidence angle $(0^{\circ} -\pm 45^{\circ})$. The experimental results are in good agreement with the numerical simulations.

Synthesis of 3-D Polarization-Rotating Surface Based on Orthogonally Inserted Parallel-Coupled Slotlines

Abstract: In this article, a second-order 3-D bandpass polarization-rotating surface (PRS) that can rotate vertically polarized incident waves by 90° and facilitate the output of horizontally polarized waves is presented. First, each PRS element is constructed using a pair of parallel-coupled slotline sections with open-short-ends, which are etched on vertically and horizontally inserted single-layer printed circuit boards (PCBs), respectively. Then, under vertically polarized incident waves, one of the slotline sections can convert the incident spatial waves into guided waves through its open end. After which, the guided waves are coupled to the other slotline section and the electric field direction will be rotated by 90° through the coupling path, thus leading to a 90° polarization rotation. Subsequently, a direct coupling matrix is used to synthesize and design the proposed PRS based on the microwave filter theory. Investigations reveal that a desirable bandpass filtering response can be obtained by properly designing the internal coupling of the parallel-coupled slotline sections and the external coupling between the incident spatial waves and the PRS. To validate the design concept, two examples with different fractional bandwidths at the same center frequency of 5 GHz and the same return loss of 20 dB were designed, fabricated, and measured. Consequently, a good agreement was attained among the results from coupling matrices, full-wave electromagnetic (EM) simulations, and measurements. All the results demonstrate that the proposed PRSs feature simple topologies, easy fabrications, low insertion losses (ILs), high polarization-rotating ratios, and stable filtering performances under large oblique incidences. In addition, our proposed method can be applied to design higher-order PRSs with sharpened out-of-band roll-off skirts.