Abstract:With the fast development of folded waveguide Traveling Wave Tube(TWT), there is an urgent need for attenuation materials with high thermal conductivity and good mechanical properties. In this study, boron-doped diamond film is prepared and the dielectric property of the film is analyzed. Meanwhile, the boron-doped diamond attenuator is fabricated and the thermal stability of the attenuator is investigated. The results show that the dielectric constant and dielectric loss tangent are 7.18 and 0.30 in W-band for the diamond film with boron concentration of 1.81×10¹⁹ cm^-3. Moreover, the return loss and insertion loss of boron-doped diamond attenuator are 19.67 dB and 44.03 dB, respectively. With the temperature increased from room temperature to 90 ℃, the return loss and insertion loss of attenuator are increased to 20.94 dB and 45.63 dB, which demonstrates high thermal stability of the boron-doped diamond attenuator.

Abstract:According to the satellite communication application requirements for high-frequency space Traveling Wave Tube(TWT), the experimental results of an E-band continuous wave space TWT are introduced. The parameters of the Folded Waveguide(FWG) slow wave structure are further optimized and the phase velocity taper scheme is adjusted to reform the gain fluctuation, improve the overall efficiency. A prototype tube is fabricated and tested with beam voltage of 14.7 kV and beam current of 74 mA, the experimental measurement results show this prototype is capable of producing an output power up to 85 W and a gain above 40 dB, with the total efficiency over 37% from 71 to 76 GHz. In addition, the TWT has achieved a beam transmission over 98% at the continuous wave operation.

Abstract:The effect of hydrogen annealing in each stage of the production of all-copper structure folded waveguide by Ultraviolet-Lithographie Galvanoformung Abformung(UV-LIGA) is studied in detail. The hydrogen annealing step is in two stages, the first stage is the hydrogen treatment of the copper substrate(early stage), and the second stage is the treatment of the substrate and the electroformed layer after realizing the metal structure(later stage). Experiments show that in addition to cleaning the substrate and reducing the internal stress, hydrogen annealing in the early stage also migrates grain boundaries, so that the grain growth tends to be stable at high temperatures, which is conducive to the growth of the electroformed layer with better combination. However, this treatment needs to be advanced before the substrate is polished, otherwise the flatness will deteriorate. In addition to testing whether the all-copper structure can withstand high-temperature welding, hydrogen annealing in the later stage also helps to further remove the photoresist and promotes grain growth of substrate and electroformed layer as a whole at high temperature.

Abstract:As a novel developing vacuum electronic device, sheet beam traveling wave tube has a wide range of application prospects in the field of radar and communications. Compared to cylindrical beam devices, there are still fewer beam-wave interaction models for sheet beam traveling wave tubes. Based on the electric circuit principles, a hybrid circuit model consisting of distributed transmission line components and lumped elements for a commonly used sheet beam slow wave structure(SWS)—staggered double vane is developed, and the feasibility of applying the model to high frequency SWS is validated.The problem of mapping from the geometrical parameters of SWS to the physical parameters of hybrid circuit is focused on. The hybrid circuit model of staggered double-vane is developed, and its dispersion relation is analyzed. Besides, a model-based Simulated Annealing(SA) algorithm procedure, capable of achieving high precision parameter fitting is coded. The results show that the proposed hybrid circuit model can accurately reproduce the dispersion characteristics of the staggered double-vane. It is significant for the subsequent development of a large signal sheet beam-wave interaction procedure based on the hybrid circuit model.

Abstract:To analyze the power and spectrum performance of the Folded Waveguide(FWG) Traveling Wave Tube(TWT) sever region, a W-band TWT with four-port structure is proposed and developed. The S-parameter of interaction circuit, power and spectrum characteristic at the sever region are obtained and analyzed. The analysis shows that the power amplitude of port 2(sever of the input segment) mainly depends on the input power of the TWT at the saturated state, which is not proportional to the gain of the input segment.The power of port 3(sever of output segment) mainly depends on the matching performance of the ports, and the calculated power is in an excellent agreement with the measured data. The study in this paper provide a practical method for designing sever region of the millimeter wave and terahertz TWTs.

Abstract:The evaluation of speech interference effect refers to the technology of analyzing the disturbed speech received by the communication system to determine speech interference effect level. Accurately evaluating the interference effect is of great significance to the development of communication countermeasure equipment, the assessment of the situation of electronic countermeasures and understanding of communication quality. As for ultra-short wave communication jamming system, a method is proposed based on Mel-Frequency Cepstral Coefficients(MFCC) features, wavelet statistical features and perceptual features, combined with the least squares, the Back Propagation(BP) neural network and Support Vector Regression(SVR) fitting regression model, the correlation coefficient between the predicted value and subjective evaluation value is above 0.9, which guarantees the practicability of the evaluation system. Secondly, the non-reference evaluation method is studied based on deep learning, and the measured data is adopted to verify the effectiveness of this method. The accuracy rate is 87%, higher than that of the multi-measure fusion evaluation method.

Abstract:The accuracy of the range-finding Radio Frequency Identification(RFID) indoor positioning algorithm will be seriously affected by ranging error. An indoor positioning algorithm based on Multi-antenna Phase Difference Of Arrival(M-PDOA) is proposed. M-PDOA ranging method is employed to measure the distance. The trilateral positioning algorithm is adopted to position the target tag. The simulation results show that the average ranging error of the algorithm is 0.102 7 m, which has a performance improvement by 65.76%; the average error of positioning is 0.180 7 m, which has a performance improvement by 56.67%, indicating that the proposed algorithm can effectively reduce the ranging errors and has high positioning accuracy.

Abstract:With the wide application of Frequency Modulated Continuous Wave(FMCW) on-board radar, the mutual interference of several radars in the same scene may lead to the decrease of sensor sensitivity and even false alarm. To tackle with this problem, an interference suppression method based on quantum genetic and center value matching is proposed. Firstly, the cross-correlation function of the transmitted waveform and the jamming signal is taken as the objective function, and the waveform parameters are optimized by Quantum Genetic Algorithm(QGA) to obtain the working parameters with the minimum cross-correlation within the constraint range. Then, the transmitted waveform is generated based on these parameters. Finally, according to the parameters of the jamming signal, the appropriate working radar parameters are selected by the center value matching method, realizing adaptive interference suppression. Simulation results show that this method can achieve good interference suppression results with low computation complexity.

Abstract:The determination method of Pulse Current Injection(PCI) waveform parameters of System Generated Electromagnetic Pulse(SGEMP) is studied by using electromagnetic norm. When the load is high and low resistance respectively, the typical response waveform of SGEMP is double exponential waveform and Gaussian waveform. Considering the difference between the rise time, the peak value, the energy and the charge carried by the equivalent waveform and the response waveform, the equivalent waveform parameters of pulse current injection are studied. The results show that the square wave equivalent waveform can simulate the response waveform according to the characteristics of the response waveform and electronic system. Therefore, it is possible to use electromagnetic norm to parameterize the equivalence of SGEMP response waveform, and the equivalent waveform can be easily generated in laboratory, which provides a new way for the study of SGEMP by the current injection method.

Abstract:A dual circularly polarized antenna covering X-band is designed. Two vertical Vivaldi antennas are fed by a 3 dB coupler to achieve dual circular polarization. In order to achieve broadband miniaturization, the Vivaldi antenna is slotted and a slot-coupled 3 dB coupler is adopted. The simulation results show that the overall size of the designed antenna is 0.48λ×0.48λ×0.5λ(λ corresponding to the wavelength at the lowest frequency); it can achieve Left-Handed and Right-Handed Circular Polarization(LHCP/RHCP) with Voltage Standing Wave Ratio(VSWR)<2 and 3 dB of Axial Ratio(AR), 40% of bandwidth from 8 to 12 GHz.

Abstract:Infrared spectroscopy can effectively carry the information of compound structure and compound composition, which has been widely used in chemical research, purity detection and drug identification. However, in practical application scenarios, due to the lack of standard sample preparation conditions, the low accuracy and low recognition efficiency of infrared spectroscopy also make this technology limited. By using a tunable infrared Quantum Cascade Laser(QCL) as the source, an experimental system for recording the diffuse reflection spectra of powder samples is established. Taking the diffuse reflectance spectrum of a mixed powder of glucose and polyethylene as an example, the Kubelka-Munk(K-M) equation and the Kramers-Kronig(K-K) relations are utilized to synthesize the transmission spectrum of the sample from the experimentally measured diffuse reflectance spectrum of pure glucose, and the possibility of the transformation of the transmission spectrum from the diffuse reflectance spectrum is verified. On this basis, spectroscopic data are applied to two neural network models to predict the mass fraction of mixed powder. The results show that the Long Short-Term Memory(LSTM) predicts the best results under the K-K relations, significantly better than the BP neural network. Under the K-M equation, both neural networks are more accurate in predicting the glucose samples with high mass fraction and poorer in predicting the glucose samples with low mass fraction. Both diffuse reflectance spectral correction methods improve the accuracy of the training results, and the LSTM prefers to the BP neural network. This work contributes to the development of the identification of unknown mixed powder samples based on frequency-tunable or broad spectral infrared lasers.

Abstract:In order to accurately and efficiently analyze the needs of power customers, thereby reducing the costs of power enterprises and increasing the added value of power service products, based on Analytic Hierarchy Process(AHP), the importance of conditional attributes is calculated, a priority relationship matrix is constructed, and the weight of power customer demand is determined by combining with fuzzy relationship judgment scales. The purity of decision tree nodes is measured and the indicator analysis is conducted on discrete and continuous node variables to determine the accuracy of power customer demand weights. A correlation extraction model is established for power customer demand, and a user profile is obtained. Taking the information differentiation values as the indicators of variable differentiation ability, the correlation coefficients between different variables are calculated. By designing correlation extraction algorithms, the power customer correlation results are obtained, and a user profile is got. Taking the information differentiation values as the indicators of variable differentiation ability, the correlation coefficients between different variables are calculated. By designing correlation extraction algorithms, the power customer correlation results are obtained. Among high, intermediate and low frequencies, the Mean Absolute Percentage Error(MAPE) values of this method are 87.3%,71.9%, and 54.1%, respectively. In intermediate-frequency customer data, the MAPE of this method is increased from 62.1% to 71.9%; in low-frequency customer data, MAPE is increased from 42.2% to 54.1%. This method has a good correlation effect.

Abstract:Although Iterative Closest Point(ICP) algorithm and its variant are the basic method for 3D point cloud rigid body registration, the point cloud iteration-based registration method get low convergence efficiency, severely constraining registration efficiency. In this paper, the Frobenius norm property is employed to represent error function between source point cloud and target point cloud, and due to the property of the Frobenius norm, the closest distance between 2 point clouds can be converted into a single calculation form to get transformation matrix. This method greatly reduce iteration times and registration time. The experiment in this paper is compared with three classical ICP algorithms and three learning-based algorithms on the Standford dataset and 3DMatch dataset respectively, and the registration time of fast ICP is less than that of other algorithms. When the registration accuracy is similar, the fast ICP method only has 20% of the iteration times of the traditional ICP algorithm, and 1/4 times the registration time on the Standford dataset, 1/8 times on the 3DMatch dataset of the traditional ICP algorithm. The fast ICP algorithm is more efficient when the amount of points is large.

Abstract:The proposal of memristor theory has greatly promoted the development of chaotic systems, enriching the dynamics of chaotic circuits. The operational amplifier becomes an important part of the memory circuit model due to its powerful signal processing capacity. In this paper, a simplified operational amplifier based on low power differential pair is constructed and this operational amplifier reduces the number of required transistors to two. Then, the simulation equivalent circuit model and hardware experimental circuit of a new type of second-order magnetron memristor are created. The results show that with the increase of the excitation signal frequency, the side lobe area of the "8" decreases; with the increase of the excitation signal amplitude, the side lobe area of the "8" increases. The results of circuit simulation and hardware circuit experiments have verified the validity of the new model of magnetron memristor and the accuracy of the design method.

Abstract:Fluorescent optical fiber temperature sensor uses the long-distance transmission of optical fiber technology to avoid the harsh temperature measurement environment compared with the traditional active temperature measurement equipment in contact measurement. Aiming at the disadvantage that the traditional single channel circuit readout structure is vulnerable to external interference, a two-channel small and practical fluorescent temperature measuring device is realized. The whole system is divided into three parts:optical circuit design, circuit design and program design. The idea of two channel differential subtraction is adopted to completely eliminate the DC component and basically do not contain random noise, so as to obtain a single smooth fluorescence attenuation signal. And through the calibration experiment, the functional relationship between the fluorescence lifetime and the temperature is obtained. The experimental results show that the standard temperature deviation is 0.5 °C within the temperature range of 10 °C to 130 °C, basically meeting the temperature measurement requirements in some harsh environments such as high pressure corrosion and microwave medical.