Southeast University

About: Southeast University is a education organization based out in Nanjing, China. It is known for research contribution in the topics: MIMO & Control theory. The organization has 66363 authors who have published 79434 publications receiving 1170576 citations. The organization is also known as: SEU.

Ultrawideband and High-Efficiency Linear Polarization Converter Based on Double V-Shaped Metasurface

Abstract: In this paper, a double V-shaped metasurface that can efficiently convert linear polarizations of electromagnetic (EM) waves in wideband is proposed. Based on the electric and magnetic resonant features of a single V-shaped particle, four EM resonances are generated in a V-shaped pair, leading to significant bandwidth expansion of cross-polarized reflections. The simulation results show that the proposed metasurface is able to convert linearly polarized waves into cross-polarized waves in ultrawideband from 12.4 to 27.96 GHz, with an average polarization conversion ratio (PCR) of 90%. The experimental results are in good agreement with the numerical simulations. Compared to published designs, the proposed polarization converter has a simple geometry but an ultrawideband and hence can be used in many applications, such as reflector antennas, imaging systems, remote sensors, and radiometers. The method can also be extended to the terahertz band.

Metal-free three-dimensional perovskite ferroelectrics

Abstract: Inorganic perovskite ferroelectrics are widely used in nonvolatile memory elements, capacitors, and sensors because of their excellent ferroelectric and other properties. Organic ferroelectrics are desirable for their mechanical flexibility, low weight, environmentally friendly processing, and low processing temperatures. Although almost a century has passed since the first ferroelectric, Rochelle salt, was discovered, examples of highly desirable organic perovskite ferroelectrics are lacking. We found a family of metal-free organic perovskite ferroelectrics with the characteristic three-dimensional structure, among which MDABCO ( N -methyl- N9 -diazabicyclo[2.2.2]octonium)–ammonium triiodide has a spontaneous polarization of 22 microcoulombs per square centimeter [close to that of barium titanate (BTO)], a high phase transition temperature of 448 kelvins (above that of BTO), and eight possible polarization directions. These attributes make it attractive for use in flexible devices, soft robotics, biomedical devices, and other applications.