Xidian University

About: Xidian University is a education organization based out in Xi'an, China. It is known for research contribution in the topics: Antenna (radio) & Synthetic aperture radar. The organization has 32099 authors who have published 38961 publications receiving 431820 citations. The organization is also known as: University of Electronic Science and Technology at Xi'an & Xīān Diànzǐ Kējì Dàxué.

Strong convergence result for solving monotone variational inequalities in Hilbert space

Abstract: In this paper, we study strong convergence of the algorithm for solving classical variational inequalities problem with Lipschitz-continuous and monotone mapping in real Hilbert space. The algorithm is inspired by Tseng’s extragradient method and the viscosity method with a simple step size. A strong convergence theorem for our algorithm is proved without any requirement of additional projections and the knowledge of the Lipschitz constant of the mapping. Finally, we provide some numerical experiments to show the efficiency and advantage of the proposed algorithm.

Relation between concept lattice reduction and rough set reduction

Abstract: One of the key problems of knowledge discovery is knowledge reduction. Rough set theory and the theory of concept lattices are two efficient tools for knowledge discovery. Attribute reduction based on rough set theory and the theory of concept lattices both have been researched. Since an information system, the data description of rough set theory, and a formal context, the data description of concept lattice theory, can be taken as the other one, the attribute reduction based on the same data base can be studied from these two perspectives, and researching their relation is significant. This paper mainly discusses the relation between concept lattice reduction and rough set reduction based on classical formal context, which will be meaningful for the relation research between these two theories, and for their knowledge discovery.

A Wideband-to-Narrowband Tunable Antenna Using A Reconfigurable Filter

Abstract: A novel microstrip circular disc monopole antenna with a reconfigurable 10-dB impedance bandwidth is proposed in this communication for cognitive radios (CRs). The antenna is fed by a microstrip line integrated with a bandpass filter based on a three-line coupled resonator (TLCR). The reconfiguration of the filter enables the monopole antenna to operate at either a wideband state or a narrowband state by using a PIN diode. For the narrowband state, two varactor diodes are employed to change the antenna operating frequency from 3.9 to 4.82 GHz continuously, which is different from previous work using PIN diodes to realize a discrete tuning. Similar radiation patterns with low cross-polarization levels are achieved for the two operating states. Measured results on tuning range, radiation patterns, and realized gains are provided, which show good agreement with numerical simulations.

Multiband and Dual-Polarized Omnidirectional Antenna for 2G/3G/LTE Application

Abstract: A novel multiband and vertically/horizontally polarized omnidirectional antenna is proposed for 2G/3G/LTE mobile communication systems. The proposed antenna is a combination of a modified asymmetric biconical for vertical polarization (VP) and six printed dipoles with concentric placement for horizontal polarization (HP). The VP element consists of two modified cones with different diameters, designed to work in the multiband GSM+3G/4G. Printed dipoles of the HP element are fed by a six-way power splitter printed on the substrate. The HP element is nested between two cones of the VP element, forming a compact structure. The bottom cone can be used as the reflector for VP and HP in the overlapping work frequencies band for 3G and LTE communication systems. The VP element achieves a bandwidth of 17.4% and gain of 1.5 dBi in the 806 ~ 960-MHz band. The HP element achieves a bandwidth of 35% (1880 ~ 2700 MHz) directly overlapping with the VP-element higher frequency band. An isolation of 25 dB is achieved in the overlapping band. The cross-polarization levels in the azimuth plane for both VP and HP are lower than -15 dB.

Planar Antenna for 3G/Bluetooth/WiMAX and UWB Applications With Dual Band-Notched Characteristics

Abstract: A new planar monopole antenna that covers 3G, Bluetooth, WiMAX, and the UWB bands but exhibits dual band-notched characteristic is presented. By etching one quasi-complementary split-ring resonator (CSRR) in the feed line, dual notched frequency bands centered at 5.3 and 7.4 GHz are obtained. To achieve the lower resonance over the 3G band, the transmission-line-based metamaterial (TL-MTM) loading is employed to gain the benefit that the radiation pattern is orthogonal to other resonance modes. The proposed antenna has been successfully simulated and measured. Experimental results indicate that the proposed antenna yields an impedance bandwidth of 2-12.5 GHz with VSWR<; 2, except the dual notched bands of 5.0-5.5 and 7.2-7.6 GHz. Furthermore, good group delay and transmission characteristics can be achieved in the UWB band.