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Zheng C.,Zhejiang University | Hu T.,Science and Technology on Space Microwave Laboratory | Qiao S.,Zhejiang University City College | Sun Y.,Nanjing Institute of Electronic Equipment | And 2 more authors.
2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2013 - Proceedings | Year: 2013

Utilizing Doppler effect to detect bio-signals of vital signs has been attracting more and more interests. In this paper, we propose a time-domain algorithm for the hand gesture recognition. We introduce an extended differentiate and cross-multiply algorithm to solve the null point and the codomain restriction issues in traditional Doppler radar sensors, and retrieve the Doppler bio-signals of a moving hand from the demodulated phase signals based on a configuration of 2 or 3 radar sensors for 2-D or 3-D HGRs. Simulations validate the effectiveness of the proposed approach. Our method is capable of retrieving arbitrary hand movements, making it possible to be used in a wide range of HGR applications. © 2013 IEEE.

He Z.,Huazhong University of Science and Technology | Liu B.,Huazhong University of Science and Technology | Li C.,Huazhong University of Science and Technology | He Y.,Huazhong University of Science and Technology | And 4 more authors.
Ceramics International | Year: 2015

Ba0.5Sr0.5TiO3-MgO-Mg3B2O6 composite ceramics were fabricated by a solid state reaction method and their dielectric tunable characteristics were investigated. The addition of MgO-Mg3B2O6 into Ba0.5Sr0.5TiO3 forms ferroelectric (Ba0.5Sr0.5TiO3)-dielectric (MgO-Mg3B2O6) composites. Increasing MgO content causes a decrease of Curie temperature TC and an increase of dielectric constant peak εmax. With the increase of the MgO content and the decrease of Mg3B2O6, the dielectric constant of composite ceramics increases slightly; meanwhile, the loss tangent decreases and the tunability increases. When MgO content exceeds 10 wt%, the electric field dependence of the dielectric constant of composite ceramics is well described by an additional "extrinsic" contribution due to the polar clusters, instead of Johnson's approximation. The dielectric constant and Qf0 values of composite ceramics at microwave frequency tend to increase with the increase of MgO content. The improved tunability and Qf0 values are beneficial for tunable microwave applications. © 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Lv Q.,Zhejiang University | Dong Y.,National Key Laboratory of Science and Technology on Reactor System Design Technology | Sun Y.,Nanjing Institute of Electronic Equipment | Li C.,Texas Technology University | Ran L.,Zhejiang University
2015 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2015 - Proceedings | Year: 2015

Doppler radar sensor has been widely used in non-contact bio-signal monitoring. This paper aims at recovering bio-signals from body movement. To solve the severe phase wrapping and saturation problems in large-scale body movement, as well as unwanted DC offsets and gradual changes of received microwave power problems, curve fitting technology is employed to compensate for the large-scale body movement to recover small-scale bio-signal based on a digital-IF structured, high-dynamic-range Doppler radar sensor and linearized demodulated algorithms. Experimental validations show weak bio-signal hidden in the strong body movement noise can be well extracted. © 2015 IEEE.

Xu K.,Zhejiang University | Ye D.,Zhejiang University | Zhu Z.,National Key Laboratory of Science and Technology on Reactor System Design Technology | Huangfu J.,Zhejiang University | And 3 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2015

In this paper, we present an analytical beam-forming approach capable of synthesizing differently shaped beams for circularly symmetric conformal apertures with axisymmetrical excitations. Closed form formulas of far-field radiation are mathematically derived in order to obtain rotationally symmetric radiation patterns for typical conformal apertures frequently used in satellite and flight vehicle applications, such as the cone-surfaced, truncated cone-surfaced, hybrid disc-cone and sphere-cone apertures. Based on these formulas, various shaped beams, including pencil, flat-topped and bimodal beams can be rapidly achieved by adjusting either the geometric parameters or the excitation distributions of the conformal apertures. The deterministic approach proposed in this paper provides an efficient method to synthesize specified beam shapes for the aforementioned conformal apertures. Collaborating with conventional optimization based beam forming approaches, the proposed approach can effectively shorten the time-consuming optimization in the beam forming of circularly symmetric conformal arrays, especially large conformal arrays. © 1963-2012 IEEE.

Peng Z.,Zhejiang University | Peng Z.,Texas Technology University | Chen J.,Zhejiang University | Dong Y.,National Key Laboratory of Science and Technology on Reactor System Design Technology | And 7 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2016

The state-of-the-art phased array-based digital beamforming systems suffer from disadvantages of high power consumption, high cost, and system complexity due to the massive use of transmitter/receiver (T/R) modules and high-speed digital and digital'analog mixed devices. In this paper, we point out that by proposing a new concept "complex domain" radio frequency (RF) frontend, the relatively slowly changed waveform delay information required to accomplish adaptive beamforming can be separated from wideband RF signals, based on which a self-contained beamforming system can be implemented with a low-speed baseband. By introducing vector RF multipliers in the proposed frontend, the amplitude and phase of RF signals can be simultaneously controlled by the real and imaginary parts of complex numbers, such that beamforming algorithms derived in complex domain can be directly applied without any form of transformation. By doing so, the massive use of conventional T/R modules and high-speed baseband devices can be avoided. Theoretical analysis and experimental demonstration based on commercial components have validated the proposed approach. Our method is able to significantly simplify the realization and decrease the cost of wideband digital beamforming systems, and can be widely used in low cost, power efficient beamforming applications. © 2015 IEEE.

Li H.,Zhejiang University | Ye D.,Zhejiang University | Shen F.,Zhejiang University | Shen F.,China Research Institute of Radiowave Propagation | And 5 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2015

Coupled electromagnetic resonances have various important applications in microwave engineering. Among them, the newly discovered electromagnetically induced transparency (EIT) has attracted much interest. In this paper, we explore the use of configurable electrically induced transparency to construct a microwave 'diffractive medium' whose air-like optimally matched transparency and metal-like optimally reflective opacity can be conveniently switched by a binary dc voltage. Different from EITs based on closely coupled resonances, we use decoupled electrically induced resonances to achieve a low-loss transparency along with an optimal impedance matching with air. Satisfying the condition of a lossless perfectly matched layer, such transparency and opacity can be obtained in a wide range of incident angles. We validate our approach by experimentally demonstrating two electrically controlled steering antennas based on diffractive grating effect, both with thin planar apertures and binary digital control circuits. The proposed approach can be extended to higher frequencies, achieving configurable diffractive devices at millimeter-wave and terahertz frequencies. © 2015 IEEE.

Li C.,Texas Tech University | Zhu A.,Zhejiang University | Qiao S.,Zhejiang University City College | Sun Y.,Nanjing Institute of Electronic Equipment | Ran L.,Zhejiang University
2014 Asia-Pacific Microwave Conference Proceedings, APMC 2014 | Year: 2014

This paper reports recent investigation on the possibility of human cardiac motion imaging using a continuous-wave microwave Doppler radar sensor. Compared with existing works of vital sign radar sensors that mainly focused on the heartbeat rate, the challenge is detect the actual pattern of cardiac motion. To achieve this, a DC-coupled direct conversion architecture and a digital-IF architecture can be used because both of them can avoid frequency-dependent signal distortion. A digital-IF Doppler radar sensor employing an extended differentiate and cross-multiply (DACM) algorithm was adopted to perform a series of experiments that investigate the effectiveness of noncontact cardiac imaging from different orientations of a subject. Experimental results demonstrated that in addition to detecting heartbeat rate, Doppler radar could also image one-dimensional, time domain cardiac motion that fits well with the known physiological description. Copyright 2014 IEICE.

Shen F.,Zhejiang University | Salamin Y.,Zhejiang University | Dong J.,Zhejiang University | Sun Y.,Nanjing Institute of Electronic Equipment | And 3 more authors.
IEEE Transactions on Microwave Theory and Techniques | Year: 2014

The measurement of complex permittivity of materials is of significant importance in scientific research and industrial applications. In this paper, we introduce the strongly coupled magnetic resonance previously used in high-efficiency midrange wireless power transfer to the noncontact measurement of the complex permittivity of materials. Theoretical analysis, full-wave simulation, and experimental measurements will show that the introduced high-Q-factor resonance can be used to effectively improve both the measurement sensitivity and the impedance matching to the instrument, avoiding the major weaknesses of the traditional magnetic induction method. The measurement setup can be easily calibrated for both solid and liquid materials and can provide the flexibility in noncontact measurement at a variable distance. We expect a wide range of applications to emerge from this novel approach. © 2014 IEEE.

Xu J.,Zhejiang University | Long J.,University of California at San Diego | Sun Y.,Nanjing Institute of Electronic Equipment | Ye D.,Zhejiang University | And 4 more authors.
IEEE Radio and Wireless Symposium, RWS | Year: 2015

Remote, distance-independent phase synchronization is a challenging technology for satellite network systems, especially spaceborne bi- and multi-static SAR systems. In this paper, we focus on the theoretical description, performance analysis and experimental verification of a remote phase synchronization system implemented with spatially distributed phase loops. The derivation, simulation and experimental results show that such a system is robust when the relative movement between remote microwave systems has a constant velocity. The proposed approach can also be potentially used in multi-static satellite systems with predictable movements. © 2015 IEEE.

Fen W.,Nanjing University of Aeronautics and Astronautics | Zhao Z.,Nanjing Institute of Electronic Equipment
International Journal of Simulation: Systems, Science and Technology | Year: 2016

Although electroencephalographic (commonly known as EEG) signals are accepted as a representative non-stationary time series, the event-related potential (ERP) is known to be a complicated signal produced by nonlinear dynamical processes. In this research, we built a 2-D time-invariant Logistic–Coupled Map Lattice (CML) for use in ERP analysis. The time-variant maximal Lyapunov exponent of ERP and the global correlation dimension were calculated using this model, and some quantized parameters that reflect the global characteristics of the system were obtained, enabling the discovery of information that traditional methods cannot identify. © 2016, UK Simulation Society. All rights reserved.

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