Abstract:The rapid development and evolution of civilian and defense electronic information technology, such as wireless communication, detection and sensing, security inspection, and artificial intelligence, have increasingly urgent application demands for terahertz(0.1~1 THz) technology. The terahertz band has rich spectrum bandwidth resources, and its broadband characteristics can support the implementation of future 6G high-speed communication and new generation high-resolution radar system performance. At the same time, terahertz communication and detection must overcome the high propagation path attenuation and surge of passive devices and interconnect losses, as well as the power generation and efficiency problems of active devices brought about by high frequency and short wavelength. In this paper, the development status of terahertz RF devices and integration technology are reviewed, and the research progress of the Shanghai Jiao Tong University team in overall improving the performance of terahertz front-end systems through new passive and active devices, antennas, advanced packaging, and other technical methods are elucidated.

Abstract:Automotive radars sense the traffic environment using electromagnetic wave. It is of low cost and works under all weather conditions throughout the day, so is of great importance for intelligent traffic and autonomous driving. Nowadays, researchers in this field focus on high-accuracy sensing of range and velocity, high resolution angle estimation and high performance multiple extended target tracking. In this paper, the existing methods in waveform design, antenna design, angle estimation and target tracking algorithms for automotive radar are reviewed. The recent literatures on radar anti-jamming, MIMO coding and extended target state estimation are summarized, aiming to provide an introduction and directions for future research.

Abstract:Radiation hardened electronics is a crossed and compositive subject whose radiation effects, mechanisms of radiation damage, hardening methods,test methods and simulation methods are very important for electronic system working in extreme environment. All kinds of damage effects produced by neutrons,gamma and X-rays from nuclear explosions and energetic particles from space and atmosphere are systemically hackled which includes dose rate effect,total ionizing effect,single event effect and displacement effect. The development of synergistic damage effects between radiation and environment and among different kinds of radiation are introduced in detail, including atom transfer effect on photocurrent,damage difference among single irradiation,serial irradiation and coinstantaneous irradiation of neutron and gamma ray,damage difference among proton,X-ray and neutron irradiation and synergistic effect between hydrogen and gamma irradiation. Technique evolvement of nuclear explosive,space and atmosphere radiation hardening is expatiated on. The ground test equipments and simulation software capabilities of nuclear,space and atmosphere radiation effects are summarized. Finally, the potential challenges and key techniques in the field of radiation hardened electronics after the 2020s are prospected.

Abstract:The existing Integrated Sensing And Communication(ISAC) technologies lack the framework and methods of deep integration, and it is difficult to guarantee the comprehensive demand of communication perception in future scenarios like "smart city" and "intelligent travel". Therefore, it is an urgent problem to study the ISAC technologies for Ad Hoc networks oriented to Internet of Things and the Internet of Vehicles. The method and technical scheme of the sensing-communication signal integration for Ad Hoc network are proposed, which can both guarantee the communication performance and improve the accuracy of ranging sensing estimation. A resource allocation scheme and its corresponding iterative optimization algorithm are proposed to deal with the time-spectrum resource conflict between sensing and communication tasks, in order to achieve the high reliability and strong stability of the ISAC Ad Hoc network collaborative awareness ability under limited resources. A hardware-software module prototype of sensing-communication integration is designed to guarantee high-precision clock synchronization of the whole network when Global Navigation Satellite System(GNSS) signal is weak, ensuring the collaborative sensing ability of the network, and providing the collaborative transmission support in long distances communication. In conclusion, an ISAC Ad Hoc system framework is built, including the integrated design of the sensing-communication signal and the joint optimization scheme of time-frequency resource; the corresponding hardware-software platform is developed, consisting of 4 ISAC module prototypes. In the field experiments of the corresponding platform within a range of 2 km, the proposed method can realize that the communication rate is above 320 kbps, the packet loss rate is less than 0.05%, and the sensing accuracy is less than 10 m.

Abstract:Compared with the widely used wireless system represented by microwave and wired system represented by optical fiber, terahertz band is expected to break through the bandwidth limit of microwave system in addition to its special spectral characteristics, thereby achieving a large bandwidth comparable to the optical fiber system but possessing the flexibility and intelligence of wireless system. However, it is still a great challenge to achieve broadband, intelligent and long range terahertz systems. The architecture of photonic-electronic converged intelligent terahertz systems is introduced firstly, and then the research progress and further development direction of key technologies such as terahertz source, receiver, channel monitor, array antenna and terahertz photomixer based on photonic-electronic convergence are reviewed and discussed. Here a new approach based on photonic-electronic convergence is discussed in order to solve the bottleneck of a single electronic or photonic approach.

Abstract:The research status of microwave wireless energy transmission system and its basic principles are outlined. Some advanced antenna technologies, such as Whisper beam, super gain, flat-top beam, focused beam, non-diffractive beam are introduced,which can improve the special aperture field for high transmission efficiency. Finally, the future development trends of the transmitter beam technology in microwave energy transmission system are prospected.

Abstract:The short millimeter wave and Terahertz Traveling Wave Tubes(TWTs) possess the advantages of wide bandwidth, high power and high efficiency, which show application prospects in military and civil fields such as high-resolution imaging, high-speed communication and electronic countermeasures. The development level of domestic and foreign companies and TWTs developed by author in recent years are analyzed and reviewed, covering several frequency bands such as E-band, W-band, G-band and Y-band. In order to further enhance the output power of TWTs, the technical analysis and experimental research are carried out on the innovative Folding Waveguides(FWG) structure, Phase Velocity Tapering(PVT) technology, band injection Periodic Cusped Magnet(PCM) clustering, multi-injection integration, etc., laying the technical foundation for device performance enhancement and application promotion.

Abstract:Terahertz frequency multiplier based on high-order harmonic generation of GaAs-based miniband superlattices is studied by using balance equation approach. With the presence of magnetic field, the peak power output of the frequency multiplier and its distribution in the parameter space (E_dc, E_ac) are carefully analyzed. The study shows that in the parameter plane of (E_dc, E_ac), the magnetic field has little influence on the peak size of the second and third harmonic of output power, but the magnetic field will broaden the peak area of the harmonic output power, which can improve the probability of output peak power in the parameter space of (E_dc, E_ac). When E_ac is determined, the position of the peak harmonic emission power will be affected by the Bloch oscillation frequency f_B generated by the DC electric field, the modulated Bloch oscillation frequency f_MB generated by the AC electric field, and the cyclotron oscillation frequency f_c caused by the magnetic field. The results indicate that the THz frequency multiplier based on semiconductor superlattice is a potential THz wave generator.

Abstract:Radar target detection is often faced with complex clutter characteristics. Classical detection methods are usually suitable for some specific scenarios. However, if the detection background changes, its detection performance will suffer from a great degradation. In order to effectively improve the detection performance under different clutter backgrounds, this paper proposes a matrix information geometric detector based on manifold ISOmetric MAPping(ISOMAP). This method first reformulates the problem of signal detection into a discriminative problem between two points on the matrix manifold; then, according to the training sample data and local isometric mapping, a projection matrix is adaptively learned, which transforms the matrix manifold into a discriminative low-dimensional manifold to enhance the separability between the target and the clutter; finally, the proposed algorithm is verified by simulated clutter and measured data. Experimental results show that the proposed method can effectively improve the detection performance in comparison with the classical detectors.

Abstract:With the rapid development and upgrading of mobile communication technologies, the informatization and intelligentization of all walks of life increasingly rely on the strong guarantee of wireless communications. Therefore, accurate channel information and reliable wireless coverage are crucial. Ray tracing technology can be used for various communication scenarios in different industries. By establishing effective three-dimensional environment models, based on the electromagnetic parameters of materials and antenna parameters, and relying on high-performance computing engines, optical ray technologies can be introduced into the field of electromagnetic computing, and can accurately characterize the propagation mechanisms such as reflection, scattering, diffraction, and transmission as well as their impacts on wireless systems. This paper introduces the high-performance ray tracing simulation platform developed by the authors. Focusing on the application cases of the high-performance ray tracing technology in the field of intelligent transportation, it expounds the technical advantages of the ray tracing technology in the field of wireless network planning and optimization, wireless channel modeling and channel characterization in various fields of intelligent transportation, such as railway, water transportation, highway transportation, etc. It is expected that the high-performance ray tracing simulation technology can be better leveraged to enhance the high-quality development of modern transportation.

Abstract:Unmanned Aerial Vehicles(UAV) are increasingly widely used in military, commercial and civil fields. With the increase of the number of Guavas, the impact on security, privacy and public interests has also been increasingly valued. Therefore, it is more and more important to study the target detection technology for UAV group. At present, a number of research work related to the detection of UAV swarm targets has been carried out at home and abroad. In this paper, the research status and challenges of UAV group target detection are studied. Then, aiming at these challenges, the types of UAV group target detection architecture technology are discussed. In view of the difficulty of centralized and single means to meet the needs of UAV group fine perception and situation assessment, the air-ground joint multi-domain detection architecture for UAV group targets is provided, which specifically includes networking radar, distributed spectrum passive monitoring equipment, mobile multi-spectral sensing equipment, mobile spectrum monitoring equipment. Combining the advantages of different sensing methods in different distances, different directions, different granularity and other dimensions, it breaks through the limitations of single-domain detection through cascade, collaboration and fusion. Finally, the key technologies are analyzed and summarized.

Abstract:Additive manufacturing,known as 3D printing, is gaining more attention in component weight reduction, model verification, complex structure integration forming, and damage repairing process. 3D printing technique is based on liquid and powder materials stack layer by layer, transforming CAD data to three-dimensional solids without molding or machining. In this work, a comprehensive introduction of 3D printing application in aerospace microwave devices has been accomplished. The basic concept and comparison of 3D printing is summarized. With the understanding of the research progress in 3D printing microwave devices, the development of space 3D printing technology is prospected.

Abstract:Terahertz Frequency Modulated Continuous Wave(THz FMCW) imaging technology has attracted extensive attention in the field of THz Nondestructive Testing(NDT) because of its high power, miniaturization, low cost, three-dimensional imaging and other characteristics. However, due to the limitation of microwave and terahertz devices, the terahertz signal bandwidth is difficult to expand, which restricts the range resolution of imaging. Although high carrier frequency can achieve large broadband, the accompanying low penetrability and low power will limit the application scenario of THz FMCW imaging system. Therefore, focusing on the field of terahertz wave nondestructive testing, this paper proposes a time-division frequency-division multiplexing 114~500 GHz ultra-wideband terahertz signal generation method, which is based on the quasi-optical design of multiband common aperture to achieve the common aperture of ultra-wideband signals. In addition, a multiband fusion algorithm is proposed to achieve effective fusion of ultra-wideband signals, and the range resolution is improved to 460 μm. The effectiveness of the system and algorithm is verified by artificially designed multilayer composite materials, and the high-resolution 3D imaging results of Integrated Circuit(IC) chips are obtained.

Abstract:Attitude estimation of satellite targets with the Inverse Synthetic Aperture Radar(ISAR) image sequences is a significant but challenging task. Existing estimation methods are normally focused on the extraction of critical corners or linear components from the image, which are hard to meet the real-time requirement and insufficient to exploit the prior of imaging characteristics. This paper presents a method for estimating the attitude of satellite targets based on imaging characteristics and regression networks. The imaging characteristics of satellite targets under various attitudes are firstly determined in advance and serve as the theoretical basis for subsequent dataset annotation. Thus, different from the traditional classification problem, a regression network and an estimation framework suited for attitude estimation are established. Finally, electro-magnetic simulation in millimeter frequency is carried out to validate that the proposed method can control the average attitude estimation error within 3.5°.