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Liu C.,Northern Institute of Electronic Equipment of China | Liu C.,CAS Chengdu Institute of Optics and Electronics | Lu Y.,Northern Institute of Electronic Equipment of China | Lu Y.,CAS Chengdu Institute of Optics and Electronics | And 3 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2010

Here, a hybrid backed-cavity with electromagnetic band-gap (EBG) structure and a perfect electronic conductor (PEC) is proposed for an Archimedean spiral antenna. This cavity makes the spiral antenna work operate over the 10:1 bandwidth and without the loss introduced by absorbing materials that are used conventionally to broadband spirals. Based on the artificial magnetic conductor (AMC) characteristic, an EBG is placed in the outer region of backed-cavity to improve the blind spot gain at low frequency. A PEC at the center of the structure is used to obtain high gain at high frequency. The antenna performances are improved significantly for of the low profile spiral antenna is improved significantly. A typical spiral antenna with a hybrid backed cavity is fabricated and studied experimentally. The experimental data are consistent with that of the simulation results. © 2010 IEEE.


Xue Q.,Qingdao University | Du H.,Qingdao University | Gao X.,Qingdao University | Wang Y.,Harbin Institute of Technology | And 9 more authors.
Journal of Alloys and Compounds | Year: 2014

MnO2-doped barium strontium titanate-MgO (BST/MgO) composites were sintered by the solid-state reaction method. The effect of MnO 2-doping on the microstructure and microwave dielectric properties of the BST/MgO composites was investigated. The MgO grains were found to be surrounded by Mn-rich oxides, which hindered the incorporation of Mg 2+ into the lattice of BST. As a result, enhanced comprehensive microwave dielectric performances, such as the reduction of dielectric loss and leakage current about 0.78 nA/cm2, and an increase of electric field tunability of dielectric constant about 13.8% at 5 kV/mm were obtained in MnO2-doped BST/MgO ceramics. © 2014 Elsevier B.V. All rights reserved.


Wang Y.,Harbin Institute of Technology | Liu Y.,Northern Institute of Electronic Equipment of China | Du H.,Qingdao University | Liu C.,Northern Institute of Electronic Equipment of China | And 4 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2015

A novel frequency reconfigurable microstrip antenna based on (Ba, Sr) TiO3 (BST) substrate is presented. Compared to the complicated structures in traditional reconfigurable antennas, our work is featured by a quite concise design. A theoretical model is proposed to calculate the initial antenna parameters. Both the simulation and the experiment indicate that the coupled aperture structure can efficiently overcome impedance mismatch of BST substrate and obtain a frequency tunability of 10% in Ku band by a DC electric field changing from 0 to 10 V/μm. Besides, similar radiation patterns are obtained in the operating band for both the E plane and H plane. Our study shows that the using of BST material on the frequency reconfigurable antenna is promising, and can be easily extended to reconfigurable antenna arrays. © 2014 IEEE.


Wang Y.,Harbin Institute of Technology | Liu C.,Northern Institute of Electronic Equipment of China | Sun B.,National University of Defense Technology | Liu Y.,Northern Institute of Electronic Equipment of China | And 3 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2014

A novel frequency reconfigurable microstrip antenna with a wide instantaneous operation band based on BST/MgO composite films is proposed and experimentally demonstrated. In our design, the frequency reconfigurability is achieved by altering the permittivity of BST film, and an extra Fabry-Perot resonant structure is adopted to broaden the instantaneous operation band. As a consequence, a wide instantaneous band that is nearly 26% greater is obtained in measurement, which means that the working band of our antenna can be tuned from 9.9-13.5 GHz to 10.9-14.2 GHz. This instantaneous wideband feature makes our frequency reconfigurable microstrip antenna more attractive and practical in wireless communication systems. © 2014 IEEE.


Wang D.-Y.,North China University of Technology | Duan T.,Northern Institute of Electronic Equipment of China | Zhang Y.-J.,University of International Relations
Journal of China Universities of Posts and Telecommunications | Year: 2012

In this paper, we studied the channel estimation problem for the orthogonal frequency division multiplexing (OFDM) system when the statistics of the multi-path fading channel is not known or partial known. A channel estimation approach based on polynomial approximation of the channel response is proposed. The pilot symbols are periodically inserted the channel responses for entire OFDM data sequence for exploiting channel correlation in both time and frequency domain, which is obtained from a time-variant frequency-selective Rayleigh fading channel model. Simulation shows that the method is robust to different channel statistics. Moreover, a window dimension adaptation algorithm is proposed to adapt the channel estimator to the channel statistics which further improves the robustness of the system. © 2012 The Journal of China Universities of Posts and Telecommunications.


Wang D.-Y.,North China University of Technology | Duan T.,Northern Institute of Electronic Equipment of China
Journal of China Universities of Posts and Telecommunications | Year: 2014

This paper proposes a method of blind multi-user detection algorithm based on signal sub-space estimation under the fading channels in the present of impulse noise. This algorithm adapts recursive least square (RLS) filter that can estimate the coefficients using only the signature waveform. In addition, to strengthen the ability of resisting the impulse noise, a new suppressive factor is induced, which can suppress the amplitude of the impulse, and improve the ability of convergence speed. Simulation results show that new RLS algorithm is more robust against consecutive impulse noise and have better convergence ability than conventional RLS. In addition, Compared to the least mean square (LMS) detector, the new robust RLS sub-space based method has better multi-address-inference (MAI) suppressing performance, especially, when channel degrades. © 2014 The Journal of China Universities of Posts and Telecommunications.


Li X.-L.,National University of Defense Technology | Wang H.-M.,National University of Defense Technology | Guo C.-G.,China Electronic Systems Engineering Corporation | Ding B.,National University of Defense Technology | And 3 more authors.
Journal of Zhejiang University: Science C | Year: 2012

Network virtualization is recognized as an effective way to overcome the ossification of the Internet. However, the virtual network mapping problem (VNMP) is a critical challenge, focusing on how to map the virtual networks to the substrate network with efficient utilization of infrastructure resources. The problem can be divided into two phases: node mapping phase and link mapping phase. In the node mapping phase, the existing algorithms usually map those virtual nodes with a complete greedy strategy, without considering the topology among these virtual nodes, resulting in too long substrate paths (with multiple hops). Addressing this problem, we propose a topology awareness mapping algorithm, which considers the topology among these virtual nodes. In the link mapping phase, the new algorithm adopts the κ-shortest path algorithm. Simulation results show that the new algorithm greatly increases the long-term average revenue, the acceptance ratio, and the long-term revenue-to-cost ratio (R/C). © 2012 Zhejiang University and Springer-Verlag Berlin Heidelberg.


Wang S.-F.,Northern Institute of Electronic Equipment of China | Yang J.-A.,Electronic Engineering Institute | Wen Z.-J.,Northern Institute of Electronic Equipment of China
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2015

A new method was proposed for the modulation type recognition of continuous phase modulation(CPM) in non-cooperative communication. In the developed framework, the modulation index, the symbol rate and the frequency offset were used to joint estimate the modulation type. On this basis, the blind demodulation was done according to the differential phase. The theory analysis and experimental results indicate that the proposed scheme can achieve a high discrimination of modulation type and results in blind demodulation. ©, 2015, Beijing Institute of Technology. All right reserved.


Sun B.,National University of Defense Technology | Ren B.,National University of Defense Technology | Liu C.,Northern Institute of Electronic Equipment of China | Liu Y.,Northern Institute of Electronic Equipment of China | And 2 more authors.
IET Microwaves, Antennas and Propagation | Year: 2016

In this study, the synthesis of scanning beam pattern with antenna selection for practical half-circular conformal array is achieved based on hybrid particle swarm optimisation-gravitational search algorithm (PSOGSA). A half-circular conformal dipole antenna system has been designed, fabricated and tested. The antenna element is dipole, and the digital beam forming net can control both the amplitude and phase in each channel through attenuator and phase shifter. The array confirms to a surface of half-circular metal carrier. To achieve the synthesis of scanning beam pattern with activated antenna selection, hybrid PSOGSA is introduced to optimise the excitation amplitude. To consider the mutual coupling effect, embedded element pattern is measured and utilised. Numerical comparisons and practical experimental results illustrate the advantage and accuracy of the proposed method and manufactured system in the synthesis of scanning beam and activated element selection. © The Institution of Engineering and Technology 2016.


Sun B.,National University of Defense Technology | Xing S.,National University of Defense Technology | Zhang J.,National University of Defense Technology | Li F.,Northern Institute of Electronic Equipment of China | And 2 more authors.
2016 10th European Conference on Antennas and Propagation, EuCAP 2016 | Year: 2016

A two-step convex optimization algorithm is proposed for array pattern synthesis with minimum number of antenna elements. Firstly, sparse array is synthesized based on convex optimization. Then, the optimized excitation coefficients exceeding the threshold are re-optimized again to obtain lower side lobe level. The non-uniform array and thinned array for the focused and shaped pattern have been investigated using the proposed method. Numerical comparison with other methods indicates that the proposed method has lower side lobe level in both non-uniform and thinned array. © 2016 European Association of Antennas and Propagation.

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