Abstract:A summary of a 0.34 THz standoff 3D imaging radar is presented which can be used for through-clothes imaging of person-borne concealed objects. Using a two dimensional non-uniform point-by-point scanning mode, a field of view of 0.6 m×1 m and 2 s imaging speed is achieved. The central frequency is 0.34 THz, and a 2 cm azimuth resolution at 5.8 m is obtained by using a ellipsoid with a diameter of 450 mm. In order to improve the dynamic range of the system, a phase noise cancellation structure is adopted. The Frequency-Modulated Continuous-Wave(FMCW) radar technique with a 12 GHz bandwidth is employed in the system. Imaging result shows that 2 cm range resolution can be achieved after calibration and the system can be utilized to detect concealed weapons.

Abstract:The development of a 220 GHz frequency doubler based on GaAs plannar Schottky diodes is described. The doubler works at room temperature, and its structure is very simple. A plannar Schottky varactor flip chip with four anodes arranged in anti-series is mounted onto a quartz based microstrip circuit to realize frequency multiplication. DC bias is put on the varactor through a low-pass filter circuit which is also constructed on a quartz microstrip. All the quartz circuits are glued into the waveguide block with conductive adhesive. The block is split in the E-plane and its surface is gold plated. Test data for the 220 GHz doubler show 15 mW output power with 5% efficiency when appropriate external bias resistor is selected. Over the 213-230 GHz，the output power of the doubler is above 10 mW，and the power fluctuation in this band is very small.

Abstract:For reducing mode density and lowering the risk of spurious mode competition in THz gyrotron, the mode-selective confocal waveguide system is adopted for high frequency circuit of 140 GHz HE06 mode confocal waveguide Gyrotron Traveling Wave Tube(Gyro-TWT) amplifier. Based on the analysis of RF system, the theoretical analysis about electron beam and waves interaction is presented. The structure and operating parameters of the gyro-TWT are determined by analysis of field distribution, diffraction loss, coupling coefficient and interaction between electron beam and wave. Nonlinear theory is utilized to calculate the amplifier, and nonlinear analysis shows that the interaction circuit can generate a saturated peak power of 12 kW, corresponding to a saturated gain of 38 dB, an efficiency of 17.1%, and a 3 dB bandwidth of 6 GHz at 140 GHz when utilizing a 35 kV, 2 A electron beam with 0.75 of the ratio of the transverse velocity to the longitudinal velocity.

Abstract:The quasi-optical mode converter is the main part of the high-power millimeter wave gyrotron. The converter can separate the electron beam and electromagnetic wave，reduce the reflecting microwave into the high-frequency cavity，and realize the output of transversal Gaussian beam. The Denisov launcher for 140 GHz，TE22.6-mode gyrotron has been analyzed and designed according to the mode coupling theory. And the reflecting mirrors have been designed with the geometrical optics theory and optimized by Feko simulation. According to the calculation results，the conversion efficiency of electromagnetic energy is 97.3% and the Gaussian content of output wave-beam is 93.3% for the quasi-optical mode converter，which can meet the requirements of the gyrotrons.

Abstract:A folded waveguide Slow Wave Structure(SWS) with frequency range from 94 to 220 GHz is fabricated with Ultraviolet Lithographie Galvanoformung Abformung(UV LIGA) technology. For 94 GHz folded waveguide SWS, the accuracy is≤15 μm, the output power of 94 GHz pulse Travelling Wave Tube(TWT) with the microfabricated SWS is higher than 100 W. For 180 GHz folded waveguide SWS, the accuracy is≤5 μm, the output power is higher than 100 mW with bandwidth of 11.4 GHz. For 220 GHz folded waveguide SWS, the accuracy is≤3 μm, and the attenuation factor is 240 dB/m.

Abstract:The mutual coupling between the antenna elements based on the Power Inversion(PI) algorithm deteriorates the performance of the space-time adaptive anti-jamming. Common solutions to solve the problem are analyzed and compared. A new method which can be applied to reduce the coupling in the anti-jamming satellite navigation positioning between the antenna elements is proposed. The method reduces the mutual coupling between the antenna elements by loading the electromagnetic resonance absorber in the satellite navigation anti-jamming antenna array. The experimental data show that the method can reduce the mutual coupling between the arrays by 10 dB, and therefore the anti-jamming receiver can suppress the maximum Jamming-to-Signal ratio by 5 dB.

Abstract:With the increasingly complex tracking targets and environment in radar application, the widely used Kalman filter and extended versions can track targets with less few calculations. However, it requires the system noises including process noise and measurement noise in a zero mean and Gaussian case, otherwise, it may lead to poor performance. In order to solve the problem of tracking a maneuvering target, when process and measurement noises are unknown-but-bounded, an extended set-membership filter and the tracking quality method based on information geometry are proposed. Simulation analysis shows that the set-membership filter provides distinct advantages in tracking performance including state bounding and tracking accuracy, and the maneuver behaviors of target can be identified through counting the changes of distances on the manifold.

Abstract:The small target detection in the complex sea context is a key technology for the sea search and surveillance series radar. The traditional radar system cannot guarantee reliable detection performance when encountering with these small targets. Based on the analysis of the scattered power characteristics of the sea clutter in complex sea conditions, a technical way is proposed to improve the performance of small targets in complex sea conditions by combining radar system design and sea surface small target detection technology, and ensure that under the low false alarm probability, small targets can be detected effectively and reliably on the sea.

Abstract:The application background of Unmanned Aerial Vehicle(UAV) power inspection is introduced. A new passive positioning technology－image-based transmission pole tower positioning technology is put forward. An image-based positioning algorithm is proposed, while analyzing the source of error. The aerial camera with Position & Orientation System(POS) can draw large scale of the topographic map，and The process of drawing the topographic map is actually the target positioning process. Carrier photoelectric turret equipped with high-precision POS system and high-definition camera, is utilized in the UAV transmission line inspection to complete the target tower real-time positioning, with positioning accuracy of 5 m.

Abstract:In order to study frequency offset estimation and Bit Error Rate(BER) of 8 Phase Shift Keying(8PSK) and 16 Amplitude Phase Shift Keying(16APSK) signals，two high-order constant envelope digital modulation methods 8PSK and 16APSK are introduced firstly，and then their frequency offset estimation is investigated. The communication link model is built to simulate the performance. Matrix Laboratory(Matlab) is utilized to simulate and analyze the frequency offset estimation of 8PSK and 16APSK modulation signals, under Additive Gaussion White Noise. Then coherent demodulation is conducted with the carrier frequency obtained by the frequency offset estimation. Finally, the actual bit error rate and theoretical bit error rate are compared and analyzed. Simulation results demonstrate that the noise immunity of 8PSK is better than that of 16APSK, under the condition of Additive Gaussion White Noise channel with different Signal-Noise Ratios(SNR). The performance of the frequency offset estimation method proposed in this paper approaches the theoretical value. This paper provides a reference for the design of communication systems.

Abstract:To improve the navigation and positioning precision of the rocket guidance platform, is one of the important research fields of rocket test technology. For a certain type of rocket guidance platform, an indirect output revising navigation algorithm is proposed, which is based on multiple sensors of Inertial Navigation System(INS) combined with Global Positioning System(GPS). In the algorithm, Kalman Filtering(KF) is utilized for optimum estimate of the systematic error, and the estimation results are adopted for correct inertial navigation calculating and sensor output. Simulation results show that, in the case that GPS works effectively and the rocket dynamics perform stably, the integrated navigation algorithm has obvious inhibitory effect on INS error accumulation over time.

Abstract:With the actually used frequency band going higher and higher in wireless communications, the influence of phase noise induced by imperfect carrier on Multi-Input Multi-Output Orthogonal Frequency Division Multiplexing(MIMO-OFDM) systems are becoming increasingly acute. This results in not only the destruction of the orthogonality of OFDM system carriers, but also the multiple-antenna precoding performance degradation. The influence of phase noise on MIMO-OFDM systems are composed of Common Phase Error(CPE) and Inter-Carrier Interference(ICI). In this paper, it is first analyzed that how CPE influences the performance of a MIMO-OFDM system, after which a series of novel CPE estimation algorithms are proposed based on frequency domain orthogonal pilot design; finally the validity and reliability of the algorithms are verified by system link simulation under various wireless transmission scenarios.

Abstract:In linear frequency modulation system, the receiver cannot demodulate the Doppler parameter correctly based on the return signal if the initial phase of the transmitter output is not coherent. A prior frame sequence is introduced to realize the coherence between the initial phase of the output pulse signal and the reference clock by initializing the Direct Digital Synthesis(DDS)’s phase accumulator. The proposed method is simple and practical, because it just only needs to modify the FPGA program without any changes to the hardware circuit. The effectiveness of the method has been verified by the experimental results.

Abstract:An E-band waveguide diplexer fabricated by precision machining with harmonic suppression is presented. The simulation result shows the insert loss in 71-76 GHz and 81-86 GHz pass-band is better than 1 dB. The isolation is greater than 60 dB. In the second harmonic pass-band 142-152 GHz and 162-172 GHz，the suppression is greater than 20 dB. The measured results show the insert loss is less than 0.7 dB in pass-band and the isolation is greater than 60 dB，the suppression of harmonic is 20 dB. Simulation and measurement results match very well. The excellent performance of the diplexer ensures that it is suitable for 5G E-band communication backhaul networks and has a good prospect of engineering applications.

Abstract:In order to obtain low phase noise planar oscillator, the common resonator and phase noise optimization method in push-push oscillators are studied in this paper. Firstly, a differential transmission line loaded by a coupled-pair of multiple split ring resonators is proposed to achieve weak coupling between two sub-oscillators, and the frequency selectivity of common resonator is improved. Then an X-band push-push oscillator utilizing this structure is designed and realized, and a phase noise optimization method based on active quality factor of oscillator is adopted in the design. The measured phase noise is -115.48 dBc/Hz@100 kHz offset at the second harmonic frequency of 9.52 GHz, and the suppression of fundamental frequency component achieves -54.55 dBc.

Abstract:Zero-index meta-materials have been investigated extensively for their unique electro- magnetic properties. In order to achieve the miniaturization of high performance antenna, a kind of zero-index material is designed, i.e., metal-mesh structure, by adjusting the effective plasma frequency to the desired frequency band. The numerical simulations indicate that this metal-mesh structure can improve the wave-front phase and increase the gain when this structure is introduced to a horn antenna. The front wave phase of the antenna is changed from the spherical wave to the plane wave, the corresponding gain of the antenna is increased by at least 2 dB. The effect of the geometrical parameters, including the number of mesh layers n, the distance between adjacent layers h, the period a for a single mesh layer, and the radius of the metal lines r, are investigated systematically to optimize the directional emission.

Abstract:A microstrip tunable band-pass filter based on stub-loaded Stepped Impedance Resonator(SIR) is designed, which is loaded with varactors. The SIR structure facilitates the suppression of higher harmonics and enables miniaturization of the filter. The model proposed in this paper is a multimode resonator consisting of a SIR and two stubs loaded in the center plane of the SIR. First of all, the resonance characteristics of the stub-loaded SIR is analyzed in the even-odd mode analysis method. Then，the independent control of the odd mode and even mode resonant frequency of the filter is realized by loading varactors. The tunability of the center frequency can be realized by adjusting the capacitance of the varactors. The center frequency increases with the increase of the bias voltage of varactors. The tunable filter shows a center frequency tunable range from 0.82 GHz to 1.17 GHz with less than 5 dB insertion loss and more than 10 dB return loss.

Abstract:X-ray streak camera is one of the key measurement instruments in laser inertial confinement fusion experiment for capturing transient X-ray pulse radiation during fusion. The reliability for X-ray streak camera working under strong electromagnetic pulses in laser fusion experiments is studied. A reliability model is presented and the reliability coefficients are assigned for each part of X-ray streak camera. A Failure Mode and Effects Analysis(FMEA) is carried out for X-ray streak camera. Reliability and FMEA analysis indicates that the streak tube is the most important part in the X-ray streak camera whose reliability coefficient is higher than others and the streak tube’s breakdown can cause serious problems in experiments. The reliability and FMEA analysis provides guidance to carry out electromagnetic hardening for X-ray streak camera and enhance its operation reliability under strong electromagnetic radiation environment.

Abstract:By using a folded conducting wall, the size of the microstrip antenna can be reduced and the beamwidth of the radiation pattern can be expanded. A new type of folded conducting wall is designed to decrease the manufacture difficulty and homologous costs. And a wide beamwidth right hand circularly polarized microstrip antenna based on this new type of the folded conducting wall is designed at L1 band. The simulation and measurement results show that this antenna has the advantages of small size, wide beamwidth and low cost.

Abstract:The design method utilized to small coupling Leaky-Waveguide Antenna(LWA) cannot be applied directly to the large coupling LWA. CST is adopted to extract the leaky-wave structure’s electrical parameters for designing a leaky-waveguide antenna with large coupling, and the design principle and the related physical parameters acquisition method of the high power rectangular LWA are theoretically analyzed. A 2.20 m high power rectangular LWA working in L band is designed and simulated by CST software, the results show that the gain of the antenna is 15.8 dBi and the main lobe direction is matched well with the theory. Moreover, the power handling capacity is about 1.6 GW, which provides a good choice for high power microwave application.

Abstract:A highly efficient and linear Doherty Power Amplifier(PA) which operates at 3.5 GHz World Interoperability for Microwave Access(WiMAX) band is designed. To maintain high linearity and high efficiency of the Doherty PA, a technique adjusting the baseband and harmonic impedances appropriately is applied to the carrier cell, and nonlinearity cancellation between the carrier PA and the peaking one is also utilized. The simulation results show that using the appropriate gate bias of the peaking amplifier, the proposed Doherty power amplifier can achieve the Power-Added Efficiency(PAE) as high as 63%, while the third-order Inter-Modulation Distortion(IMD3) and the fifth-order Inter-Modulation Distortion(IMD5) are less than -30 dBc.

Abstract:The bandwidth of ultra-thin sheet absorber in low frequency is difficult to broaden; therefore, a thri-square loop nested absorber loaded with resistors is designed in this paper. The substrate with high dielectric is utilized to realize broadening the frequency bandwidth. The theoretical analysis and simulation verification is described. The absorption rate of the absorber between 1.3 GHz and 1.35 GHz is more than 90% and the peak of the absorption rate is about 1.33 GHz; the absorber is insensitive to polarization and achieves high absorption rate in wide incidence angle. The effect of thickness and dielectric constant of the substrate on the absorber performance is analyzed briefly.

Abstract:With the development in information levels of wars，the complex electromagnetic environment adaptability is more and more important for radar equipments. Through the analysis on the electromagnetic environments in which radar equipments work，the compositions of the electromagnetic environments for radar equipments are determined. The performance metrics susceptible to the external environments are studied. On basis of the definition of the complex electromagnetic environment adaptability of radar equipments，the requirements of test environments, test items and test equipments for radar equipments adaptive tests are presented. The work can provide reference for the implementation of adaptive tests of radar equipments.

Abstract:A GaN broadband high efficiency power amplifier is designed based on the broadband matching network for the requirements of the broadband high efficiency power amplifier, covering the entire S band. Simulation results show that the Drain Efficiency(DE) is better than 62%, the Power Added Efficiency(PAE) is better than 57% and the gain is more than 10.6 dB. And the test results show that the DE is better than 54%, the PAE is better than 48% and the gain is more than 9 dB, the flatness of the gain is less than 1 dB, achieving the design of the broadband high-efficiency power amplifier.

Abstract:A novel amplitude equalizer is designed based on the band notch characteristic of Defected Ground Structure(DGS). To replace the resonance associated with resistance in traditional amplitude equalizer, two resistances are put into ‘I’ type of DGS. By increasing the width of microstrip line, the characteristic impedance variation effect of DGS is eliminated, so does the bad Voltage Standing Wave Ratio(VSWR). This kind of equalizer is characterized by convenient regulating, ultra wideband, small size, simple structure and easy to processing. 3D electromagnetic simulation results and testing results have proved that this amplitude equalizer can work at 12-40 GHz (Ku to Ka waveband).The Return loss is less than 13.5 dB. The equilibrium quantity can reach 17 dB. The insertion loss is 2.1 dB at sideband. The size is 8 mm×8 mm.

Abstract:In order to improve the performance of the Spatio-Temporal Context(STC) algorithm in anti-occlusion object tracking, using context model similarity as the judge criterion of occlusion and also the correction coefficient of context model renewal equation, an anti-occlusion object tracking algorithm based on STC tracking is proposed. The simulation and comparison are carried out by the standard target tracking video library. The experimental results show that the robustness of the anti-occlusion tracking is improved on the basis of the original algorithm. In some image sequences, the tracking success rate can be increased by 30%.

Abstract:In order to detect signal of Automatic Dependent Surveillance-Broadcast(ADS-B) precisely, an improved detection algorithm is developed in this paper. And a special match filter for ADS-B is proposed, which benefits from the phase coherence of the pulse train from the first ADS-B preamble pulse to the third format bit. State machine is developed to ensure decode signal in correlate peak. The simulation results show that it is able to increase detection probability by this method under low ratio of signal to noise. The sensitivity of receiver using this method is -95 dBm(the packet error rate is 5%).

Abstract:Aiming at studying the bioelectromagnetism problem of using antenna as a radio frequency radiation source, by using 3-dimensional electromagnetic simulation software(High Frequency Structure Simulator, HFSS) based on Finite Element Method(FEM), the model of influence on human head exposuring to the radiation caused by the mobile antenna, and cab’s driver occupational electromagnetic exposure model of subway are simulated. The influence of the settings of radiation boundary condition and Perfect Matching Layers(PML) on the accuracy of the simulation results in electric small size model and electric large size model is analyzed. Comparing with existed literature's simulation results of time domain finite difference method, the reliability of perfect matching layers with thickness of λ/2 as the boundary condition is verified. Combining the accuracy of the simulation results, the number of grid segmentation and the speed of calculation, it is indicated that the antenna near-field radiation problem of electric small size model should choose the second-order basis function for grid mesh, and electric large size model should choose the mixed basis function for grid mesh.

Abstract:The percolation characteristics of the core determine the distribution of oil and gas and storage information. Using digital core technology to establish the pore network model is very important for the simulation and percolation analysis of the true core pore structure. The macroscopic percolation characteristics of the pore structure are determined by their microscopic characteristics, so it is important to study the characteristics of the percolation path. In order to analyze the seepage characteristics of the pore structure on the microscopic level, the search algorithms of the connected path and the percolation path are studied. Then, the definition and calculation formula of the relevant parameters of the percolation path characteristics are put forward. Finally, the path search results of the pore network model and the percolation path characteristic parameters are presented.

Abstract:A hardware architecture of processor based on Field Programmable Gate Array(FPGA)+ Digital Signal Processor(DSP) structure is proposed. In order to solve the problem of large amount of computation and long time in most real-time processing of Synthetic Aperture Radar(SAR) algorithm, a new hardware solution based on multi-core DSP and Serial Rapid I/O (SRIO) is proposed. Since multi-core DSP makes the processing speed in the chip faster and SRIO makes the data transmission between chips faster, this paper mainly discusses the main flow of implementing SAR algorithm by using multi-core DSP and SRIO based on FPGA+DSP architecture and optimizing the Fast Fourier Transform(FFT) algorithm by using pipeline technology in multi-core DSP. By using multi-core DSP, pipeline technology and SRIO technology, the data operation and transmission rate are faster, and the goal of shortening the calculation time is achieved.

Abstract:The control and protection logic in the monitoring and controlling system of the antenna guarantees the security for the operation of the antenna equipment. In view of the requirements of the monitoring and control system of the antenna, the control strategies of various protection modes for the antenna movement are compared, and the kernel control flow of the antenna is proposed. Based on the real-time alarm information processing methods, a kind of software control and protection logic for abnormal processing of the antenna monitoring system is designed, and the debugging strategy and method of the logic program in the laboratory environment are devised. The logic programs only can be used as a simulation test in the laboratory environment and the programs needs to be improved in the real environment(with antenna and real sensors). Security system design and implementation of the antenna system is complex. This paper provides a method to formalize and simplify these problems.

Abstract:In order to improve the diagnostic rate of analog circuit parametric fault, a new fault diagnosis method based on multi-feature extraction and Random Forest(RF) algorithm is presented. By combining the time domain and frequency domain feature vectors for multi-feature vector data to reflect different faults, the decision is made by RF algorithm, the number of decision tree and candidate feature vectors are optimized. The fault diagnosis experiment results show that the proposed method can better realize analog circuit fault diagnosis, and shows a better classification performance compared with Support Vector Machine(SVM) method, and compared with wavelet(packet) feature extraction method, the multi- dimensional data feature extraction is simplified for online fault diagnosis.

Abstract:An L-band self-bias internal matching power amplifier is proposed. The amplifier is fabricated by using 0.25 μm GaN High Electron Mobility Transistor(HEMT) chips, and internal matching techniques are utilized to perform input–output matching, and the operating frequency band of the amplifier is 1.2-1.4 GHz. Using self-bias technology, and single power supply, the circuit is more simple and easy for use. The working conditions are 28 V, 10% pulse duty ratio and 300 μs pulse width; when the input power is 26 dBm, the output power in the band is greater than 40 dBm, and the power added efficiency is more than 60%, which fully shows the performance advantages of GaN power devices in a single power supply module.

Abstract:The optical filter based on mechanically-induced π-phase-shifted Long-Period Gratings(LPGs) formed by pressing a bend-insensitive fiber from two sides with two identical periodically grooved plates are investigated. The influence of the sub-grating number and pressure on the spectrum characteristics of the π-phase-shifted LPG are investigated experimentally, together with the Polarization Dependent Loss(PDL). The results show that the depth of the two lateral rejection bands varies with the strength of pressure applied to the fiber; the pass-band width of the grating depends strongly on the number of the sub-grating, while the central wavelength of the pass-band is independent of it. For LP13 mode coupling, the pass band width varies from 8.2 nm to 53.8 nm when N increases from 2 to 9. A maximum PDL of about 6.86 dB for LP13 cladding mode is measured. It is believed that the mechanically-induced π-phase-shifted Long Period Fiber Gratings(LPFGs) with the merits of reconstructable, simple and easy operation have potential applications in fields of fiber-optic communications and fiber-optic sensing.

Abstract:The design principle of the True-Time Delay(TTD) chip is studied. Based on GaAs PHEMT technology, the ultra wideband TTD is designed and fabricated. The TTD chip is characterized with ultra wideband, large time delay and compact size and mainly applied to wideband active phased array applications. The measured results on wafer show that the 6 bit TTD provides 10 ps up to 630 ps with an interval of 10 ps in the frequency range 3 GHz to 17 GHz. The Root Mean Square(RMS) error for all 64 bit states is below 8 ps. The insertion loss is below 22 dB. And the 64-states insertion variation is reduced to ±1 dB. The input and output Voltage Standing Wave Ratio(VSWR) are better than 1.7 on the whole bandwidth. The dimension of the chip is 4.0 mm×2.6 mm×0.07 mm. The simulation results are in good agreement with the measured results.