Time filter

Source Type

Cao Y.,Tongji University | Wei Z.,Tongji University | Wu C.,Tongji University | Li H.,Tongji University | And 2 more authors.
Optics Express | Year: 2012

In this paper the transmission properties of a metal plate perforated with a triangular array of air holes is investigated. We find that the normalized transmittivity exceeds unity within a certain frequency range under normal incidence of a Gaussian beam. Calculations and experiments indicate that the phenomenon results from the collimation effect which only occurs inside the complete bandgap of surface resonance states on the perforated metal plate. The findings present a simple approach for beam collimation. © 2012 Optical Society of America. Source

Zhang L.,Shanghai JiaoTong University | Wang H.,Shanghai JiaoTong University | Qi J.,CAS Shanghai Advanced Research Institute | Wu Y.,Shanghai JiaoTong University | Peng S.,Shanghai Radio Equipment Institute
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2015

Colloidal carbon microspheres were prepared from aqueous glucose solutions by hydrothermal synthesis procedure, and then submicron core/shell structured precursors of carbon spheres/ ZrW2O8 were prepared by sol-gel method with colloidal carbon microspheres as templates to provide reactive surfaces for facilitating the deposition of nano-sized ZrW2O8 particles. Finally, hollow spheres of ZrW2O8 can be produced by calcinating the precursors at 610℃ for 10 h to remove the colloidal carbon sphere templates. The final spheres ZrW2O8 with an average size about 3 μm were proved to be composed of single phase nano-sized ZrW2O8 particles. Their density was measured to be 2.8 g/cm3, ca 45% lower than that of ZrW2O8. Along with the density, FTIR and TG-DTA results also indicate the existence of hollow structure of the spheres ZrW2O8, of which the thermal expansion coefficient was -11.4×10-6 K-1 in the temperature range from room temperature to 200℃, a little higher than the theoretical value. © All right reserved. Source

Ding B.,Hefei University of Technology | Ding B.,Shanghai Radio Equipment Institute | Wu J.,Hefei University of Technology | Fan W.,Hefei University of Technology | And 3 more authors.
Plasma Science and Technology | Year: 2015

Electron density and Faraday rotation angle are important physical parameters in nuclear fusion research. To measure them simultaneously, the three-wave polarimeter/interferometer diagnostic system is applied. Both the final probe output signal and the reference signal contain three frequency components. The time-varying phase difference curve of each frequency component can be measured by the Real-time Dynamic Spectrum Analysis (RDSA) method based on Field-Programmable Gate Array (FPGA). The phase difference precision is better than 0.1° and the real-time feedback delay is less than 1 ms, which satisfy the requirements of HL-2A. Source

Huang Q.,Shanghai University of Electric Power | Wu B.H.,Shanghai Maritime University | Gao L.,Shanghai Radio Equipment Institute | Guo D.M.,Shanghai Radio Equipment Institute | Tong M.L.,Shanghai University of Electric Power
Advanced Materials Research | Year: 2014

Phased array radar (PAR) used for space exploration is a potential technique in many fields such as space target detection, tracking and orbit determination. Nevertheless, it may take a long time for PAR to detect fast-moving targets due to the large searching scope. This paper introduces the compressive sensing (CS) theory used in phased array tracking radar. A fast target searching method and angle-range imaging algorithm based on CS theory are presented, which can reduce the scanning time, sampling and processing data storage. The results of numerical simulation indicate that the proposed method using fewer scanning times can retain almost equal imaging and resolution quality compared to conventional method, which can also ensure the signal-to-noise ratio (SNR) of target detection. © (2014) Trans Tech Publications, Switzerland. Source

Cao Y.,Shanghai Radio Equipment Institute | Cao Y.,Shanghai Key Laboratory of Electromagnetic Environmental Effects for Aerospace Vehicle | Wang X.,Shanghai Radio Equipment Institute | Wang X.,Shanghai Key Laboratory of Electromagnetic Environmental Effects for Aerospace Vehicle
Progress in Electromagnetics Research Symposium | Year: 2014

Metamaterials (MMs) refer to a class of artificially engineered structures comprised of electric/magnetic resonant building blocks much smaller than the operating wavelength. The extraordinary electromagnetic responses of MMs, not available for naturally occurring materials, have attracted intensive investigations on the underlying physics as well as related applications. In recent years, MMs-based antennas are widely studied and proved to have great potential in improving the radiation performance. In this paper, a MMs-based Febry-Perot cavity antenna with wide viewing angle is proposed about 14 GHz. The antenna consists of a high-impedance surface which works as an artificial magnetic conductor (AMC) at resonance frequency and a partially reflective surface (PRS). The AMC loading contributes to the low-profile and high-gain property of the antenna, as the AMC ground plane gives a near-zero phase shift in contrast to conventional metal sheet ground plane. The lateral size of the antenna is only about 3λ × 0:6λ; and the thickness is about λ/5. Metal walls surrounding the limited aperture are introduced to prevent the leakage of cavity mode and improve the radiation pattern, which also protects the antenna from external electromagnetic environment. The MMs-based high-gain antenna has a broad beam width in H-plane, which may be applied in ETC and RFID system. Source

Discover hidden collaborations