This work presents a polarization-phase hybrid modulation (PPHM) method based on time-modulated array (TMA) architecture that enables independent dual-circularly polarized beam generation through hybrid modulation of 2-bit phase states and orthogonal polarization components. By implementing optimized time sequences, the method produces left-handed circular polarization (LHCP) at the +1st harmonic and right-handed circular polarization (RHCP) at the -1st harmonic without additional components such as polarization converters. Simulations on a 16-element uniform linear array at 10 GHz demonstrate high-purity circularly polarized radiation across three beam directions (-20°/-40°, 20°/40°, and- 40°/40°), and sidelobe levels (SLLs) below -15 dB, cross-polarization suppression exceeding -20 dB, and axial ratios (ARs) persistently below 2 dB within the 3-dB beamwidths.

In this paper, a full-polarized beamforming method based on time-modulated array (TMA) is proposed. This TMA consists of a linearly polarized reconfigurable antenna unit with a 2-bit phase modulator. By properly controlling the 2-bit phase and polarization state in time domain, arbitrary polarization and continuous amplitude and phase can be achieved at the carrier frequency. Simulation results show that at the carrier frequency, the array can achieve a flat-top beam with an angular range of -20°< θ<20°, a ripple level below 0.5 dB and a sidelobe level (SLL) less than -26 dB.

In this paper, the R band (220-325GHz) five-fold module is designed using a reverse parallel Schottky varactor diode pair produced by Teratech. The reverse parallel diode pair is used to generate the nonlinear components with harmonic input in V band (50-75GHz).The electromagnetic three-dimensional model of Schottky diode is simulated, the parasitic effect of the diode is considered, and the detailed design method of each part is given. The quintuple multiplier has a maximum output power of -9dBm at 220-330GHz.The designed frequency multiplier experiment test shows that when the input power is 5dBm, the output frequency range is 260-330GHz, the output power is greater than -11dBm, the conversion loss is less than 16.5dB, and the width between the band is up to 23%.Compared with the previous academic results, the proposed drive power is smaller, the harmonic frequency is higher, the frequency band is higher, especially the band width is more than 20 GHz.

The application of electronic communication effectively shortens the distance between people, promotes the development process of economic globalization, and effectively promotes the country’s economic development. This paper analyzes the key technologies in electronic communication, such as security protection technology, satellite communication technology, alignment and tracking, and discusses the switching between different communication networks and broadband network technology under its network framework, so as to promote the continuous development of electronic communication technology in China.

Radar performs target detection by transmitting electromagnetic waves and reflecting them on obstacles. It is widely utilized in military, rescue and other occasions because of the advantages beyond visual range and not restricted by lighting conditions. Since electromagnetic waves have different penetrating capabilities in different frequency bands, it is possible to penetrate the wall to image the life target on the other side of the wall by selecting the appropriate frequency band. When multiple micro-moving targets are detected by life-detection radar, the targets are lost in the image due to the mutual occlusion of the targets. In this paper, a multi-target imaging method based on multi-station radar is proposed. Two stepped-frequency continuous waves (SFCW) MIMO radars detect targets by forming multiple-stations to obtain multi-directional scattering information of targets. A target image is obtained based on a back-projection (BP) image algorithm, and three image fusion methods of information weighted image fusion, fuzzy logic image fusion and M-N-K detector image fusion are adopted to generate the images of multiple micro-moving targets, including occluded targets. In the experiment, the three image fusion methods are analyzed separately, and the experimental results show that the three methods can effectively recognition the occluded targets.

Visualization of human postures is of great significance for research in areas such as autonomous driving, smart home monitoring and AR human interaction. However, RGB cameras and two-dimensional radar arrays commonly exploited for visualization of human postures have problems such as susceptibility to environmental interference and high cost. Based on this, the paper proposes a method to visualize human postures using radar time-frequency time-frequency spectrograms. A stepped-frequency continuous wave (SFCW) radar is needed to obtain radar time-frequency spectrograms in one direction, which realizes the visualization of human postures from the initial state of human and radar time-frequency time-frequency spectrograms. Experimental results demonstrate that this algorithm effectively solves the problem of using multiple radar information to visualize human postures.

In this paper, the millimeter wave radar amplification device is designed using the MWG303 power amplifier chip of Milliway Electronic Technology Co., Ltd. The whole device comprises an input waveguide microstrip transition structure based on Rogers 5880 and an output waveguide microstrip transition structure based on quartz. And waveguide structures such as waveguide turn and waveguide lift, in this design, the waveguide microstrip transition circuit is designed and simulated in the 3D electromagnetic field simulation software HFSS of Ansoft Company, and then the parts are combined, and the micro-assembly test is carried out after CAD processing. The results show that the gain can reaches more than 10dB. The design has the advantages of high gain, good flatness, practical structure and so on.

In this paper, we consider the problem of DOA estimation for a mix of incoherent and coherent targets by using the monostatic co-prime MIMO array with N sparse transmitting sensors and 2M - 1 sparse receiving sensors. The co-prime MIMO array generates a non-redundant and uniform sub sum co-array with O(MN) contiguous sensors using only O(M + N) physical sensors. Based on the concept of sum co-array equivalence, we can obtain different configurations of virtual MIMO arrays with O(MN) contiguous virtual sensors, and then construct the corresponding virtual data matrices, which provides different tradeoffs between the number of resolvable targets and the maximum number of mutually coherent targets that can be resolved. On the basis of the virtual data matrix and the conventional DOA estimation approaches such as MUSIC, O(MN) mixed coherent and incoherent targets can be resolved only with O(M + N) physical sensors, namely the number of resovable targets exceeds the limitation of the number of physical sensors. Finally, simulation results demonstrate the effectiveness of the proposed DOA estimation method with the monostatic co-prime MIMO array in the presence of both the coherent and incoherent targets.

For the traditional DOA estimation of coherent and incoherent targets based on monostatic (massive) uniform dense array, the number of resolvable targets is limited to the number of physical sensors. To exceed the limitation, it is desirable to have sparse transmitting and receiving arrays. In this study, we consider the monostatic co-prime MIMO array with N sparse transmitters and 2M-1 sparse receivers in the DOA estimation of mixed coherent and incoherent targets. The sparse co-prime MIMO array with O(M+N) physical sensors generates a non-redundant and uniform sub-coarray with O(MN) contiguous sensors in the sum co-array. Based on the defined wide-sense or narrow-sense sum co-array equivalence, we can obtain different configurations of virtual MIMO arrays with O(MN) contiguous virtual sensors, and then construct the corresponding virtual data matrices, which provides different tradeoffs between the number of resolvable targets and the maximum number of mutually coherent targets that can be resolved. On the basis of the virtual data matrix and the conventional DOA estimation approaches such as MUSIC, O(MN) mixed coherent and incoherent targets can be resolved only with O(M+N) physical sensors, namely the number of resolvable targets exceeds the limitation of the number of physical sensors. Furthermore, the application of two additional operation frequencies extends the contiguous sub-coarray accompanied with the improvement of degree-of-freedom for more resolvable coherent and incoherent targets. Finally, simulation results demonstrate the effectiveness of the proposed DOA estimation method.

It is a usual practice for improving spectrum quality by the mean of designing a good shaping filter to improve signal-noise ratio in development of nuclear spectroscopy. Another method is proposed in the paper based on discriminating pulse-shape and discarding the bad pulse whose shape is distorted as a result of abnormal noise, unusual ballistic deficit or bad pulse pile-up. An Exponentially Decaying Pulse (EDP) generated in nuclear particle detectors can be transformed into a Mexican Hat Wavelet Pulse (MHWP) and the derivation process of the transform is given. After the transform is performed, the baseline drift is removed in the new MHWP. Moreover, the MHWP-shape can be discriminated with the three parameters: the time difference between the two minima of the MHWP, and the two ratios which are from the amplitude of the two minima respectively divided by the amplitude of the maximum in the MHWP. A new type of nuclear spectroscopy was implemented based on the new digital shaping filter and the Gamma-ray spectra were acquired with a variety of pulse-shape discrimination levels. It had manifested that the energy resolution and the peak-Compton ratio were both improved after the pulse-shape discrimination method was used.

Low conversion loss (CL) and high isolation graphene harmonic mixer with inductor-capacitor resonators and microstrip reflective stubs (MRS) is presented in this paper. The nonlinear electromagnetic field characteristics of the multilayer graphene are similar to those of an antiparallel diode pair, which has very strong nonlinear characteristic and is suitable for the development of the Low-level even-combinatorial-frequency harmonic mixer. Through the reflection of radio frequency (RF) signal and local oscillator (LO) frequency signal, the CL of graphene harmonic mixer is significantly reduced, and the isolation between the ports is also improved. The measured minimum CL at the LO power of 16dBm is about 19.2dB, and 2-3dB lower than that without MRS over the frequency band from 2.05-2.5GHz, while the isolation between ports is better than 30dB.

This paper focuses on direction finding using a co-prime array from the view of a difference co-array. According to the corresponding relationship between the correlation lag and virtual element position of the difference co-array, from the correlation matrix of the co-prime array, the desired correlation units are extracted as single-snapshot data of the virtual co-array elements of the co-prime array and are then coherently accumulated into a pseudo-beam pattern. Because the difference co-array of a co-prime array consists of a group of contiguous virtual elements and multiple non-uniform virtual elements, this paper considers pseudo-beam-forming using only contiguous virtual elements, as in existing studies, and all of the virtual elements. Compared with the existing sub-beam multiplication method, pseudo-beam-forming reduces the negative effect from grating lobes and resolves more uncorrelated sources than the number of physical elements. Moreover, application of non-uniform virtual elements improves the resolvable source number, angle resolution and noise immunity, which are analyzed quantitatively based on the proposed distribution characteristic of virtual elements. Finally, to suppress side-lobe interference caused by the non-uniform virtual elements, we introduce and evaluate three coherence weighting factors, namely coherence factor (CF), phase coherence factor (PCF) and sign coherence factor (SCF), where CF is proved to be ineffective and SCF is optimal in suppression and computation performance.

Under the condition of single-frequency operation for co-prime array,discarding the non-uniform virtual elements in the difference co-array brings about the number loss of the resolvable sources in DOA estimation.This paper proposed a DOA estimation algorithm to improve the number of the resolvable sources based on the co-prime array with dual-frequency operation.By selecting single proper additional operation frequency,it obtained the additional different positions of virtual elements in the difference co-array to fill two missed virtual elements in the difference co-array of co-prime array with the reference operation frequency.Compared with the single-frequency operation,the proposed dual-frequency operation acquired more uniform virtual elements,improving the degree-of-freedom of DOA estimation which resulted in the DOA estimation for more incoherent sources.More specifically,corresponding to a co-prime array with N + 2M-1 physical elements,the dual-frequency operation improves the degree-of-freedom by M and increases the number of resolvable incoherent sources in DOA estimation by M.

Semiconductor detector is widely used in energy dispersive X-ray fluorescence measurementsdue to its excellent per-formance.In this paper,Si-PIN and CdTe semiconductor detectors were studied,performances of the two detectors were com-pared in material properties,detection efficiency,energy resolution and other aspects.Focused on the performance of the detec-tors influenced by the thickness of detector sensitive area,energy of incident X-ray,shaping time of post-stage circuit,and ana-lyzed the differences of energy spectrum caused by escape peaks and hole trailing.Aiming at the problem of incomplete hole col-lection in detector,a digital multi-channel analyzer (DMCA)based on FPGA with rise-time discriminator was designed,it could reduce the influence of hole trailing effectively and improve energy resolution.The experimentation results indicate that the de-tection efficiency of Si-PIN and CdTe is roughly equal when energy is below 1 5 keV while CdTe has much higher detection effi-ciency than Si-PIN when energy is above 15 keV.The optimum forming time of the Si-PIN detector is about 10μs,and the CdTe detector is about 2.6μs,so the CdTe detector is more suitable for the high count rate condition.Si-PIN detector has better ener-gy resolution than CdTe detector for different energy incident X-ray.CdTe detector has obvious hole tailing effect and the energy resolution of CdTe detector is significantly improved by using DMCA with rise-time discrimination.

Wavelet analysis is commonly used to detect and localize peaks within a signal，such as in Gamma-ray energy spectra. This paper presents a peak area estimation method based on a new wavelet analysis. Another Mexican Hat Wavelet Signal (MHWS) named after the new MHWS is obtained with the convolution of a Gaussian signal and a MHWS. During the transform, the overlapping background on the Gaussian signal caused by Compton scattering can be subtracted because the impulse response function MHWS is a second-order smooth function, and the amplitude of the maximum within the new MHWS is the net height corresponding to the Gaussian signal height, which can be used to estimate the Gaussian peak area. Moreover, the zero-crossing points within the new MHWS contain the information of the Gaussian variance whose valve should be obtained when the Gaussian peak area is estimated. Further, the new MHWS center is also the Gaussian peak center. With that distinguishing feature, the channel address of a characteristic peak center can be accurately obtained which is very useful in the stabilization of airborne Gamma energy spectra. In particular, a method for determining the correction coefficient k is given, where the peak area is calculated inaccurately because the value of the scale factor in wavelet transform is too small. The simulation and practical applications show the feasibility of the proposed peak center and area estimation method.

为满足便携式核辐射污染监测系统研制需求,设计了一种基于SiPM的小体积α、β放射性活度测量装置.该装置的探测器部分以塑料闪烁体和SiPM为核心,使用该新型探测器能够保证高灵敏度的同时缩小系统体积;计数器部分以FPGA为核心,包含了去抖动、边沿检测、脉冲计数、数码管显示等单元;探测器输出的微弱电流脉冲信号依次经后级电荷灵敏放大、整形滤波、电平转换电路的处理,最终以标准TTL电平信号的形式输出给脉冲计数器,实现对放射性粒子的实时监测.测试结果表明:装置对α源的探测效率约为43.3％,对β源的探测效率约为11.5％,能够有效完成α、β放射性活度测量.

首先分析了《数据结构》课程教学在传统教学模式下所存在的问题,探讨了以微课为技术手段制作案例,并将案例应用于《数据结构》教学的混合式教学模式,详细阐述了案例的实施过程,实践证明能够充分调动学生的主动性,实现良好的师生互动和反馈,有效提高了教学效果.

The problem of "University-College-Department"positioning is not accurate,the division of labor is not clear to students'innovation and entrepreneurship education recently.The idea of establishing the linkage cooperation system of the "University-College-Department"is proposed,and the system adopts the four-tier architecture to implement the sub-level education. The innovation and entrepreneurship education is decomposed of the professional education,competition education,innovation education,and entrepreneurship education .And it is classified to be implemented in professional department in colleges,associate school and school organization,respectively,thus forms the pyramid mode of innovation and entrepreneurship education. It can fully arouse the enthusiasm of the masses of professional teachers and benefit more discipline and specialty of having a great number of university students.

该文研制了一种高性能的液体转移监控系统,该系统采用AD7705型∑-△模数转换器,对称重传感器的微弱电压信号进行放大并数字化处理,使用ATmega16单片机进行PID控制,输出PWM信号到直流水泵驱动电路板,用以调节直流水泵的给水量,最后实现容器中波面的动态平衡,该系统可广泛应用于液料的定量转移.

Design and construct a system based on the APP software "WeChat", which is used to realize the re-al-time monitoring of environmental radiation dose rate .The system with the help of third party cloud platform server to connect the radiation monitor into the Internet , through the network cloud platform specific network in-terface to the radiation monitor and WeChat server to establish a binding connection .The upper interface in the WeChat app uses HTML 5 based scripting language design , underlying radiation monitor with NaI scintillator collocation photomultiplier tube and back -end WiFi module , MCU module completes the data acquisition and processing .In the aspect of data communication protocol , the combination of Websocket and MQTT is used to improve the communication efficiency of the system .The system can realize the remote monitoring of the radia-tion monitor , the interface design is simple , the operation is convenient , the real-time performance is good , the communication efficiency is high .