The State Key Laboratory of Millimeter Waves

Nanjing, China

The State Key Laboratory of Millimeter Waves

Nanjing, China
SEARCH FILTERS
Time filter
Source Type

Che B.-J.,Harbin Institute of Technology | Meng F.-Y.,Harbin Institute of Technology | Meng F.-Y.,The State Key Laboratory of Millimeter Waves | Lyu Y.-L.,Harbin Institute of Technology | And 7 more authors.
Applied Physics A: Materials Science and Processing | Year: 2016

An efficient method for the challenge design of an omnidirectional wireless power transfer system (OWPT) is proposed. The OWPT is realized utilizing the rotating magnetic field, which is generated by the proposed 2-D transmitter. The transmitter is composed by two mutually perpendicular loops fed by two excitation sources with the same magnitude and 90° phase difference. An OWPT system prototype is fabricated and measured. Experimental results demonstrate that the system can deliver power to receivers moving around the transmitter with a steady transfer efficiency. Furthermore, the magnitude distribution of the rotating magnetic field can be controlled by the feeding phase difference between the two loops. This capability enables the OWPT system to focus energy for device moving in a limited receiving angle range. © 2016, Springer-Verlag Berlin Heidelberg.


Kong Y.,South China University of Technology | Chu Q.,South China University of Technology | Chu Q.,The State Key Laboratory of Millimeter Waves | Li R.,South China University of Technology
Progress In Electromagnetics Research B | Year: 2013

Two efficient unconditionally-stable four-stages split-step (SS) finite-difference time-domain (FDTD) methods based on controlling parameters are presented, which provide low numerical dispersion. Firstly, in the first proposed method, the Maxwell's matrix is split into four sub-matrices. Simultaneously, two controlling parameters are introduced to decrease the numerical dispersion error. Accordingly, the time step is divided into four sub-steps. The second proposed method is obtained by adjusting the sequence of the sub-matrices deduced in the first method. Secondly, the theoretical proofs of the unconditional stability and dispersion relations of the proposed methods are given. Furthermore, the processes of obtaining the controlling parameters for the proposed methods are shown. Thirdly, the dispersion characteristics of the proposed methods are also investigated, and numerical dispersion errors of the proposed methods can be decreased significantly. Finally, to substantiate the efficiency of the proposed methods, numerical experiments are presented.


Kong Y.,South China University of Technology | Chu Q.,South China University of Technology | Chu Q.,The State Key Laboratory of Millimeter Waves | Li R.,South China University of Technology
Progress in Electromagnetics Research | Year: 2013

High-order unconditionally-stable three-dimensional (3-D) four-step alternating direction implicit finite-difference time-domain (ADI-FDTD) methods are presented. Based on the exponential evolution operator (EEO), the Maxwell's equations in a matrix form can be split into four sub-procedures. Accordingly, the time step is divided into four sub-steps. In addition, high-order central finite-difference operators based on the Taylor central finite-difference method are used to approximate the spatial differential operators first, and then the uniform formulation of the proposed high-order schemes is generalized. Subsequently, the analysis shows that all the proposed high-order methods are unconditionally stable. The generalized form of the dispersion relations of the proposed high-order methods is carried out. Finally, in order to demonstrate the validity of the proposed methods, numerical experiments are presented. Furthermore, the effects of the order of schemes, the propagation angle, the time step, and the mesh size on the dispersion are illustrated through numerical results. Specifically, the normalized numerical phase velocity error (NNPVE) and the maximum NNPVE of the proposed schemes are lower than that of the traditional ADI-FDTD method.


Kong Y.-D.,South China University of Technology | Chu Q.-X.,South China University of Technology | Chu Q.-X.,The State Key Laboratory of Millimeter Waves | Li R.-L.,South China University of Technology
Progress In Electromagnetics Research B | Year: 2012

The stability and numerical error of the extended four-stages split-step finite-difference time-domain (SS4-FDTD) method including lumped inductors are systematically studied. In particular, three different formulations for the lumped inductor are analyzed: the explicit, the semi-implicit, and the implicit schemes. Then, the numerical stability of the extended SS4-FDTD method is analyzed by using the von Neumann method, and the results show that the proposed method is unconditionally-stable in the semi-implicit and the implicit schemes, whereas it is conditionally stable in the explicit scheme, which its stability is related to both the mesh size and the values of the element. Moreover, the analysis of the numerical error of the extended SS4-FDTD is studied, which is based on the Norton equivalent circuit. Theoretical results show that: 1) the numerical impedance is a pure imaginary for the explicit scheme; 2) the numerical equivalent circuit of the lumped inductor is an inductor in parallel with a resistor for the semi-implicit and implicit schemes. Finally, a simple microstrip circuit including a lumped inductor is simulated to demonstrate the validity of the theoretical results.


Lu Y.,Zhejiang University | Lu Y.,Chinese Academy of Sciences | Dai G.,Zhejiang University | Dai G.,Ningbo Institute of Materials Technology and Engineering | And 3 more authors.
Progress in Electromagnetics Research | Year: 2013

In this paper, we present a broadband out-of-phase power divider with high power-handling capability. The proposed device consists of several sections of double-sided parallel-strip lines (DSPSLs), a mid-inserted conductor plane, and two external isolation resistors, which are directly grounded for heat sinking. A through ground via (TGV), connecting the top and bottom sides of DSPSLs, is employed. The special metal via is realized to short the isolation resistors at full-frequency band when the odd-mode is excited. Meanwhile, it can be ignored as the excitation is even-mode. This property is efficiently utilized to improve the bandwidth. To examine the proposed power divider in detail, a set of closed-form equations are derived. Meanwhile, the power operation analysis illustrates that the proposed power divider is a good candidate for high power applications. The design charts show that the proposed device can support a wide frequency ratio range (1-1.7). Furthermore, broadband responses can be obtained when proper frequency ratios are adopted. For verification, an experimental power divider operating at 1.25/1.75 GHz is implemented. The measured results exhibit a bandwidth of 44.3% with better than 15 dB return loss and 18 dB port isolation is achieved. © 2010 EMW Publishing.


Kong Y.-D.,South China University of Technology | Chu Q.-X.,South China University of Technology | Chu Q.-X.,The State Key Laboratory of Millimeter Waves
Progress in Electromagnetics Research | Year: 2012

A new approach to reduce the numerical dispersion of the six-stages split-step unconditionally-stable finite-difference time-domain (FDTD) method is presented, which is based on the split-step scheme and Crank-Nicolson scheme. Firstly, based on the matrix elements related to spatial derivatives along the x, y, and z coordinate directions, the matrix derived from the classical Maxwell's equations is split into six sub-matrices. Simultaneously, three controlling parameters are introduced to decrease the numerical dispersion error. Accordingly, the time step is divided into six sub-steps. Secondly, the analysis shows that the proposed method is unconditionally stable. Moreover, the dispersion relation of the proposed method is carried out. Thirdly, the processes of determination of the controlling parameters are shown. Furthermore, the dispersion characteristics of the proposed method are also investigated, and the maximum dispersion error of the proposed method can be decreased significantly. Finally, numerical experiments are presented to substantiate the effciency of the proposed method.

Loading The State Key Laboratory of Millimeter Waves collaborators
Loading The State Key Laboratory of Millimeter Waves collaborators