Abstract:The Ommic CGY2191UH chip model is reconstructed to establish a D-band amplifier module model. A D-band amplifier module is designed and fabricated to verify the accuracy of the model. The D-band amplifier module model consists of two waveguide models, two coplanar waveguide-rectangular waveguide transition models, two gold bonding wire models of the equivalent circuit model and a CGY2191UH chip. Based on current domestic technology, a D-band amplifier module is designed and fabricated. The test results show that the module would obtain a gain greater than 4.5 dB in 110 GHz-140 GHz, and the biggest gain at 122 GHz is 10 dB. Gain test curves agree with the model simulation results well, which validates the model.

Abstract:Plasma antenna has unique physical properties of stealth, dynamic reconfiguration etc., which is different from metal antenna, and it shows broad application prospects in remote sensing, communications and navigation. In order to study the influence of the plasma frequency on the characteristics of the antenna, a cylindrical plasma antenna model is established in the three-dimensional electromagnetic simulation software. It is analyzed how the plasma collision frequency influences the performance of S11 curve, pattern and gain etc. and some conclusions are given.

Abstract:To improve the poor resolution and low signal-noise ratio of terahertz image, by using the adaptive manifolds and high-dimensional filtering, a terahertz image denoising algorithm is proposed. The median filter is firstly used to remove the serious noise in the terahertz image. Then the filtered image is processed by the adaptive manifolds for high-dimensional filtering where the most of remained noise is removed in this step. Finally the Laplace of Gaussian based edge enhancement method is performed to enhance the output image. The experimental results show that the proposed method performs well in removing the noise with edge and details preserving.

Abstract:Spintronics is an exciting discipline that involves the study of active control and manipulation of spin degrees of freedom in solid-state systems, the study of spin transport and invention of novel spin-based devices. Some physical phenomena in spintronics, such as exchange magnon, antiferromagnetic resonance, ultrafast spin dynamics, present characteristic frequencies in the THz range. Utilizing the physical principles, the researchers have found and developed several novel THz wave generation methods which give instructions to develop novel THz sources. The methods include: a) THz wave generation based on spin injection; b) THz wave generation based on antiferromagnetic resonance;c) THz wave generation based on ultrafast spin dynamics. THz wave generation methods based on spintronics have great potential which may promote the progress of THz technology.

Abstract:A parametric control method based on Matlab is studied. GRASP9 simulation interface is called by Matlab program, and the antenna electric performances of millimeter and sub-millimeter wave radiometer are batch processed. Taking the installation error of quasi optical feed network in principled sample machine as an example, the main beam efficiency is analyzed by the displacement and angle deviation of ellipsoidal mirror. Under the displacement deviation within 0.5 mm and angular deviation within 0.4°, the main efficiency can meet 90% of the indicators requirements or more. The theoretical calculation results are in good agreement to the test results, which verifies the effectiveness of the parameters control.

Abstract:Compared to traditional terahertz holographic imaging algorithm for short-distance targets based on spherical wave decomposition, the same imaging compensation formula is obtained based on the theory of stationary phase method. By analyzing the effect of array elements error on imaging results using the criterion of image entropy, it provides the theory basis to the design of the array elements position precision of imaging system. Aiming at the defocusing and fuzzy in 3-D targets imaging results at non-compensation distance which is too close, the defects of traditional imaging algorithm are analyzed, and terahertz 3-D holographic imaging method is proposed for short-distance target based on the combination of loop compensation and projection synthesis. The Matlab simulation results at 220 GHz show the effectiveness of the proposed method, which realizes the focused imaging of three-dimensional targets.

Abstract:Aiming at the low efficiency problem of the traditional paring method used in the uplink Cooperated Multi Point(CoMP) system, a user properties based adaptive user grouping algorithm is proposed. By taking the users’ properties as parameters, the proposed algorithm could determine the number of groups with Min-Max distance measure method, then divide users into several groups with k-means method. Therefore, users are divided into several groups according to their properties. The simulation results show that the proposed algorithm can increase the uplink sum capacity of the system, and it is still effective even under low Signal to Noise Ratio(SNR). The advantages of multi-antenna at the base station side facilitate improving the uplink sum capacity of the system.

Abstract:The application of location and velocity measurement by multiple satellites to earth objects is very important. The intrinsic relationship for location model between satellite electronic reconnaissance and Global Navigation Satellite System(GNSS) is firstly analyzed. The non-cooperation velocity measurement model for radiation objects through the multiple electronic reconnaissance satellites is naturally established based on the GNSS principle. Then the instance is further discussed when the number of satellite decreases to three. The simulations demonstrate that the velocity precision about 5 m/s is acquired on condition of frequency difference of 2 Hz. This is an important reference for radiation object velocity measurement application by the electronic reconnaissance satellites.

Abstract:A matrix decomposition method is presented，which is applied to 3-D reconstruction of Inverse Synthetic Aperture Radar(ISAR) target. By the modeling of target motion in the scene, the ISAR imaging process of the target is given. The projection matrix of the relationship between two-dimensional position coordinates of scattering point in image sequence and the three-dimensional coordinates for original target is derived. By using the basic method of matrix decomposition based on orthogonal projection, the decomposition of 3-D position matrix for primary target scattering points from the observation matrix is realized, and then the 3-D position reconstruction for target is completed. The simulation results validate its effectiveness.

Abstract:To suppress the Co-Channel Interference(CCI) and increase the number of served users in multi-user distributed Multiple Input Multiple Output(MIMO) systems, a joint transmit antenna selection and pre-coding scheme is proposed based on the characteristics that there are a large amount of antennas at the base station in distributed MIMO systems. In the proposed scheme, downlink transmits antenna selection and Signal to Leakage and Noise Ratio(SLNR) pre-coding are combined together. On the one hand, it selects different antennas for each user to radically decrease the CCI. On the other hand, during the antenna selection process, antenna ports are firstly selected according to the trace of the channel sub-matrices. Then antennas which minimize the SLNR loss for each user are selected with an elimination method in order to make interference to other users as small as possible and further suppress the CCI. Compared with the optimal algorithm, the proposed algorithm shows great superiority on complexity with a capacity performance similar to the optimal algorithm. It can make the system provide service to more users than SLNR pre-coding under the same capacity constraint.

Abstract:The echo simulator is of great significance to the research on Synthetic Aperture Radar (SAR), whereas it costs massive computation. In order to realize fast simulation of SAR echo, the Field Programmable Gate Array(FPGA) is adopted as the kernel chirp to design the digital signal processing board specially used in SAR echo simulation. The simulation algorithm is realized on the board by programming. The application result shows that the realization of SAR echo simulator based on FPGA can greatly accelerate the simulation speed and significantly reduce energy consumption.

Abstract:Miss distance is an important index in measuring the performance of guidance and control system. Based on the radio-laser combination fuze, a post-test miss distance estimation method is proposed by developing the relationships among the miss distance, activation distance, and miss distance direction. Both slide rail testing and flight testing demonstrate the high accuracy of the proposed miss distance estimation method. Furthermore, the universality of the proposed estimation method makes it possible to be used for a post-test estimation of miss distance with similar mechanism.

Abstract:Polarization mismatch due to environmental factors including the attitude variation of carrier, rain-fading and multipath effect etc., usually results in poor quality of communication or even being unable to communicate for mobile satellite communication antenna. For resolving the problem, based on analysis and research on polarization, a technology of electrical polarization adjustment is proposed to realize polarization calibration. This technology can adjust polarization state in real time by controlling the amplitude and phase of a pair of orthogonal linear wave, which makes the polarization states of transmitting and receiving antennas match well, and ensures obtaining the maximum electromagnetic energy and improves the quality of communication. Experiment results indicate that the cross polarization isolation can reach up to 30 dB for on-the-move antenna with an equivalent diameter of 0.6 m at Ku band. Therefore, it can meet the requirements of satellite communication.

Abstract:Compact polarimetric Synthetic Aperture Radar(SAR) has a congenital advantage in marine surveillance over full polarimetric SAR for its wider swath. A new ship detection method on compact polarimetric SAR image based on weighted Support Vector Machine(SVM) and m-χ decomposition is proposed. Firstly, the proposed method constructs the weighted feature vectors by extracting the compact polarimetric parameters. Then, the ship targets in compact polarimetric SAR image are detected by the weighted SVM classifier. Finally, the false alarms are wiped off according to scattering mechanism strength differences corresponding to the three components of m-χ decomposition. The NASA/JPL AIRSAR airborne full polarimetric data and the Radarsat-2 satellite-borne full polarimetric data are used to simulate the compact polarimetric data in the Circular Transmit-Linear Receive(CTLR) mode, and the experimental results show that the method performs well in detecting ship targets, and can remove the false alarms and ambiguities effectively.

Abstract:The calibration of channel amplitude/phase errors is necessarily required in order to achieve the performance of low side-lobe digital array. The relationships among channel amplitude/phase errors, array channels and the main performance (side-lobe level, beam direction, gain) of digital array are analyzed. Analysis results show that, the side-lobe, gain and beam direction would deteriorate as the amplitude/phase errors increase; the influence degree of amplitude/phase errors on the side-lobe level and beam direction would decrease as the number of the array channels increase; the influence of amplitude/phase errors on gain is independent on the number of the array channels. According to the adjustment problem of channel amplitude/phase errors in digital array application, as a complementary method of measuring the channel amplitude/phase errors, the principle, implementation methods and application conditions of internal-monitor and mid-field measurement are studied in detail. A calibration method of channel amplitude/phase errors is put forward. Simulation results show that after calibration, the channel amplitude/phase errors decrease from 2 dB and 20° to 0.4 dB and 2° respectively，which meets the expected specification.

Abstract:The near field analysis of antennas is necessary in the Near Field Communication(NFC), Electromagnetic Compatibility(EMC), array antenna design and so on. Accurate and efficient method of near field analysis plays an important role in the distribution control and the leading mechanism of the near field. In view of the typical magnetic dipole antenna(electrically small loop) for near field theory research, the near field energy distribution, active power(radiation power) distribution and reactive power(non-radiation power) distribution are analyzed. The average Poynting vector could be calculated through the magnetic dipole field component and then the relation between the stored energy and the radiation energy can be qualitatively analyzed. At the same time, the small electric loop near field stored energy flow in the physical image is given. The average electric field energy density and the average magnetic energy density are also calculated and compared.

Abstract:A novel charge-conservation method with particle zigzag-line moving is introduced and it is implemented and applied in a large-scale parallel code named NEPTUNE3D for fully electromagnetic Particle-In-Cell(PIC) simulation programmed by authors. Compared with the classical PIC method, this zigzag-line charge-conservation method does not need Boris-correction which involves large linear-equations for solving problem, so it has a better robustness. Compared with other charge-conservation methods, this zigzag-line charge-conservation method does not need any judgment sentence, so its code executive efficiency is higher and it is suitable for massively parallel computation. Compared with the classical PIC method, two real devices are simulated and tested by using NEPTUNE3D with zigzag-line charge-conservation method, one is the entire high power microwave tube including magnetic transmission line oscillator and antenna, the other one is a terahertz folded waveguide travelling-wave-tube. The zigzag-line charge-conservation method simulation results are correct and agree with the classical PIC method well. Moreover, as computation duration being shortened notablely, device-design and simulation efficiency could be boosted obviously by using this new zigzag-line charge-conservation method.

Abstract:A novel circularly polarized holographic antenna is proposed at 35 GHz based on optical holographic principle. The antenna is composed by sources and an interference plane which is based on quasi-periodically artificial impedance surface. The surface impedance of scalar artificial impedance surface is analyzed by transverse resonance technique. In order to achieve circular polarization, a phase modulation is introduced into the function of the interference plane impedance. The antenna radiates circularly polarized wave from linearly feed. As an example, a circularly polarized holographic antenna is simulated. The results indicate that the beam deflects 35° along z axis, and the axial ratio is below 1.5 dB at 35 GHz center frequency.

Abstract:Magnetic latching relay are widely used in military and civilian electronic equipments, including aviation, aerospace, electronics, telecommunications and other fields. Its performance is vulnerable and easily being affected by external magnetic environment. The impacts from magnetic fields with different magnitudes and different directions on magnetic latching relay are analyzed. By studying the shielding effects of protective hoods with different thicknesses and different sizes, it is obtained that, increasing the thickness of shield or reducing its size can improve the shielding effect. This work can provide engineering implementation basis for electromagnetic protection of magnetic latching relay.

Abstract:A magnetic shielding room is designed in order to evaluate the magnetic shielding effect on low-frequency magnetic fields. A kind of shielding scheme is proposed，in which the shielding effect is studied under the joint influence of static magnetic field and alternating magnetic field. The experimental results show that for the proposed electromagnetic shielding room, indoor static magnetic field B≤200 nT，50 Hz AC magnetic interference<0.10 μT，greater than 100 kHz AC magnetic shielding factor S≥1 000，which meets the practical requirements of the magnetic sensor system. This work can provide a necessary theoretical basis for the shielding effect evaluation of shielding room.

Abstract:The stability of antenna phase center is important for navigating and locating precisely in navigation system. To meet the technical requirements, a circularly polarized navigation antenna which is used in two frequency bands with high stability of phase center is designed. By using the structure of double air-box coupling antenna and feeding by two feed points，a wide frequency band and high phase center stability can be obtained. Both of the simulated results and the measured results show that the stability of phase center is less than 1.72 mm. The antenna is applicable and feasible.

Abstract:According to the development of handheld wireless devices，a multi-band antenna is designed. It can be applied to the Beidou satellite navigation system, Global Positioning System(GPS)，and Wireless Local Area Networks(WLAN). The structure is based on Planar Inverted F-shaped Antenna(PIFA). Two L-shaped slots are grooved around the edge of the radiation patch. The antenna can work at 1.575 GHz,2.445 GHz and 5.32 GHz with wide enough bandwidth，and meet the frequency requirements of above mentioned wireless systems. The distribution of the current on the patch surface is analyzed，and performance of antenna influenced by the location，shape and size of slots is investigated by using electromagnetic simulation software. Experimental results verify the properties of this design.

Abstract:An orientation method based on directional antennas is proposed according to the difference of signal coverage area. The transmitter transmits different signals to different directions, and the coverage areas of different signals would be overlapped to some extent, therefore the receiving terminal can receive one or more different signals. By analyzing the signals received, the receiving terminal’s direction relative to the transmitting terminal can be determined according to the transmitter signal overlay. The proposed orientation method can determine the direction without satellite positioning signals, mobile data network services or paving locating nodes in advance.

Abstract:The phase noise composition and characteristics of a digital Phase Locked Loop(PLL) are investigated. A phase locked frequency synthesizer based on crystal oscillator multiplication is presented. Compared with the traditional frequency synthesizer based on single PLL，the proposed design achieves lower phase noise. According to the test results，the phase noise of -109.1 dB/Hz@10 kHz is achieved by the traditional approach when the output is 6 480 MHz; while a better phase noise performance of -117 dB/Hz@ 10 kHz is reached by the proposed design at the same frequency，using the same crystal oscillator PLL chip and Voltage Controlled Oscillato(VCO), which is improved by 8 dB compared to the traditional design.

Abstract:A Self-Adaptive Fruit Fly Optimization Algorithm(SAFOA) is proposed in order to further improve the performance of Fruit Fly Optimization Algorithm(FOA). A fruit fly search group pattern is designed, and then a self-adaptive variable-step search algorithm is put forward. Simulation results indicate that SAFOA features fast rate of convergence, strong global search and local optimization performance, and high convergence precision in comparison with FOA and Diminishing Step Fruit Fly Optimization Algorithm(DS-FOA).

Abstract:The Inductor Capacitor Inductor(LCL) type Inductive Power Transfer(IPT) system is a kind of new resonant topology for IPT system，with a larger power transfer capability and a more complicated frequency characteristic than the conventional LC resonant one. To deal with the high order nonlinear and complex frequency characteristics, the resonant parameter compensation method is presented by impedance analysis based on the mutual coupling model. The frequency and power transfer performance with load variation are analyzed and then the power transfer and efficiency computing method are presented. Simulation results have verified the theoretical results.

Abstract:A method for determining the discounting factor of each intuitionistic fuzzy evidence based on intuitionistic fuzzy cross-entropy is proposed to treat the reliability among the evidences for different sources and avoid the conflicts. It can be used in the intuitionistic fuzzy evidence combination to improve the efficiency of D-S combination algorithm. The score function simply used in the intuitionistic fuzzy decision is improved according to the certainty factor to discuss the final results of the combination. Experiments comparison with other approximations indicates the proposed algorithm is of effectiveness and high-performance in the multi-source information fusion.

Abstract:According to the characteristics of non-core information system, one new heuristic attribute reduction algorithm is proposed based on mutual information, in which the evaluation of attribute importance depends on two indexes, the increment of mutual information and the information entropy. When one attribute is added to the reduction sets, the attribute with the largest attribute importance is selected for the core attribute. This method can solve the problem of increased computational complexity caused by the randomly selected attributes. The simulation experiments indicate that the proposed algorithm is effective, which can not only improve the efficiency of attribute reduction, but also decrease the number of attribute reduction.

Abstract:The Multiple Signal Classification(MUSIC) algorithm requires multipath number estimation. The eigenvalue decomposition and spectral peak searching feature high computational complexity. To address the issues, a new root time delay estimation based on noise subspace approximation is proposed. The proposed algorithm uses the high power inverse matrix to approach the product of both noise subspace and its conjugate transpose. The polynomial is constructed for estimating time delay. The polynomial rooting avoids the spectral peak searching and reduces the computational complexity. Simulation results show that the proposed algorithm has the similar performance as the MUSIC algorithm and approaches the Cramer-Rao Bound(CRB) without multipath number estimation; and the computational complexity of the proposed algorithm is lower than that of the MUSIC algorithm.

Abstract:Fixed-point Digital Signal Processing(DSP) is widely used in the engineering applications because of its characteristics like high speed, low consumption, low cost and being programmable. However, the data dynamic range of fixed-point DSP is extremely narrow, which will cause “data overflow” when calculating the complex modulus according to its definition. An optimized method based on the traditional approximate calculation of complex modulus is put forward and realized on the fixed-point DSP. It can greatly increase the accuracy of the calculation of complex modulus in the guarantee of no data overflow.

Abstract:Single Photon Detector(SPD) is a kind of instrument with ultra-low noise and extremely high sensitivity. It is able to detect and count the smallest energy quantum-photon, to realize the detection of weak signal. Superconducting Nanowire Single Photon Detector(SNSPD) is one of new type SPDs, which has many advantages over traditional SPD, including high count rate, low dark counts and so on. However, it is only when SNSPD runs at critical state on bias mode and works with many other modules that could trigger hotspot effect. In this paper, a bias power supply system is designed for the experimental system of SNSPD based on superconducting characteristics of NbN, coupled with functions of temperature control and signal conditioning. Experiment shows that stable parallel constant current biases can be output from four channels with a precision of 0.1 μA, a range from 0 to 99.9 μA, and temperature precision of 0.05 K; and pulses generated by hotspot effect are regulated through signal conditioning and then detected successfully by analytical instrument, which can meet the requirements of single photon detection.

Abstract:A semi-supervised Adaptive Boosting(AdaBoost) model tree based modeling approach is proposed for Field Programmable Gate Array(FPGA) performance characterization. The proposed approach, which adopts AdaBoost to improve the prediction accuracy, constructs an analytical performance model with regard to the FPGA architecture parameters in semi-supervised learning way. The FPGA performance model built through the proposed approach estimates the area, delay and area-delay product with Mean Relative Errors(MREs) of 4.42%, 1.62% and 5.06%, respectively. Compared to the supervised model tree and the previous semi-supervised model tree algorithm, the proposed approach boosts the estimation accuracy by 39% and 26% respectively. Experimental results show that the proposed approach is proved to be an efficient FPGA characterization approach, building FPGA performance models with high accuracy in less time cost. The proposed modeling approach can be applied to explore the FPGA architecture design space effectively and efficiently.