The modular multilevel matrix converter (M3C) is suitable for high-voltage and high-capacity AC/AC conversion due to its modular characteristics and easy expansion. However, the M3C topology has problems such as complex hardware circuits, mutual coupling of input and output frequencies, and special operating points, making it difficult to conduct modeling analysis and control strategy analysis. This paper utilizes dual-dq transformations to achieve decoupling between input and output frequencies, realizing independent control of both the input and output sides. Furthermore, addressing the issue of equal frequency operation in the M3C system, a frequency operation control strategy based on low-frequency circulating current injection was proposed. The proposed method does not require injecting common mode voltage or applying reactive power. Simulation results based on the M3C verify the effectiveness of the proposed method, and the dynamic and static performance of the control strategy is also validated.

According to the basic principles of quasi-optical and gaussian beam, the quasi-optical mirror and lens are studied, and a set of millimeter-wave antenna quasi-optical feed system is designed, which can realize two channels of 89–183 GHz to receive electromagnetic radiation signals at the same time. The quasi-optical calculation and preliminary results are completed. The system works in low-temperature Dewar, in view of the actual needs, the locations and beam radius of the quasi-optical device are constrained and continuously optimized.

This paper presents the transmission characteristics of flexible solid circular dielectric waveguides in the terahertz frequency band. In this paper, we measured the electrical properties of certain polymers within 325–500 GHz. Through simulation and measurement, the transmission loss, bending loss, and electric field distribution of solid-core polymer dielectric waveguides were analyzed and discussed. Additionally, we considered the surrounding cladding of the dielectric waveguide, the signal-feeding mode transmitter, and the interconnection of the dielectric waveguide. Ultimately, in the operating frequency range of 325–500 GHz, we selected PTFE rods with diameters of 0.5 mm and 1 mm as the dielectric waveguides, with measured transmission loss of less than 30 dB/m and 33 dB/m, respectively, and bending loss of less than 1 dB/m. The described dielectric waveguide has engineering significance for short-distance connections in complex geometric environments and provides a reference for subsequent research.

Based on the fundamental principles of quasi-optical and Gaussian beams,research has been conducted on quasi-optical reflectors and lenses,leading to the design of a quasi-optical feed system for millimeter-wave and submillimeter-wave antennas.This system is capable of simultaneously receiving electromagnetic radiation signals in the 89～115 GHz and 176～183 GHz frequency bands through two optical paths.Elliptical reflectors and lenses are utilized to focus the beams and control the system's structural envelope.Polarization grid networks are employed to separate channels,and calculations and preliminary analysis of dual-channel performance are conducted.The system operates in a low-temperature environment,and in response to practical requirements and cold optical analysis,constraints are proposed and optimized for the spatial position and beam radius of quasi-optical components.Theoretical calculations and simulation results indicate that the system meets the design requirements for cold optics and quasi-optics.

This paper presents a terahertz high gain beam steering transmitarray antenna (BSTA) working at 340 GHz. Substrateless double hexagon ring slots unit-cells which present low loss characteristics at THz band are used to constitute the layout of THz BSTA. To improve the beam steering performance, bifocal technique is used to design the layout of BSTA. Because the fabrication risk of the THz BSTA prototype increases a lot as the aperture dimension is enlarged, four inch silicon wafer is chosen after weighting the risk and gain of the BSTA. Micromachining process is used to fabricate the large aperture THz BSTA to ensure the machining accuracy of the unit-cells. The measured results of the prototype show that the THz BSTA could realize. - 15 degrees similar to 15 degrees range beam scanning with gain > 38:3 dB, scanning loss < 1:2 dB, and side lobe level < -17.8 dB, by moving the feed along the focal plane of the BSTA.

This paper presents a WR-2.2 band waveguide orthogonal mode transducer (OMT) for an ice cloud remote sensing radiometer. A holistic approach is proposed to the design and manufacturing. Given the difficulties of using computer numerically controlled (CNC) milling techniques to fabricate the OMT and its assembly, both the design and fabrication processes are optimized to reduce the possibility of error, which could affect OMT performance. In the design, the OMT utilizes a side-arm structure, with a compact 90° waveguide twist designed in the side-arm path to reduce insertion loss and achieve two symmetric and opposing output ports in the radiometer. Regarding the challenges in CNC milling technology for such high frequencies, a comprehensive sensitivity analysis is performed following the OMT design to identify the design parameters with high sensitivity. Then, an acceptable tolerance range for CNC milling is obtained. To control fabrication uncertainty and minimize tolerance, an effective fabrication refinement strategy is proposed for accessible CNC machining, reducing the range of fabrication errors to − 3 to 2 µm within 3 iterations. Comprehensive measurements and analyses are performed on the fabricated OMT as well as the one with an antenna and a receiver. The measured insertion losses of the H and V copolarization of the OMT are better than 1.4 dB and 2 dB, respectively. The isolation is better than 40 dB. The measured H and V cross-polarizations are better than 25 dB. They demonstrate the OMT with a good performance for radiometer system.

In this paper, a high-power 170 GHz frequency doubler based on a Schottky diode is proposed using an in-phase power-combining structure. Unlike a conventional power-combining frequency doubler, the proposed frequency doubler utilizes the combination of a T-junction power divider and two bend waveguides to eliminate the phase difference between the two output ports of the T-junction power divider, so as to achieve in-phase power combining with a concise structure. The frequency doubler was fabricated on a 50 μm thick AlN high-thermal-conductivity substrate to reduce the impact of the thermal effect on the performance. The measured results show that the doubler exhibits a conversion efficiency of 11–31.3% in the 165–180 GHz band under 350–400 mW of input power, and a 118 mW peak output power with a 31.3% efficiency was measured at 174 GHz `when the input power was 376 mW. A good agreement was achieved between the simulation results and the measured performance of the doubler, which proves the effectiveness of the proposed in-phase power-combining structure.

Dielectric spectroscopy plays an important role in the biological diagnosis but there are limited publications on cultured live cells, like PC12 cells. In this paper, the complex permittivity of PC12 cells was measured and characterized using a free-space method in the range of 140–220 GHz. In the cell suspension experiment, a relaxation phenomenon was observed, regardless of the density of cell suspension. In addition, measurements on PC12 cells grown on patches of filter paper yield more information pertaining to biological behaviors of PC12 cells. It has been found through this work that the more live cells ae seeded on paper, the higher the complex permittivity becomes.

A three-phase to single-phase modular multilevel converter based advanced co-phase traction power supply (MMC-ACTPS) system is an effective structure to address the concerns of phase splitting and poor power quality of the conventional electrified railway. Due to the large number of MMCACTPS system modules, I/O resources and computing speed have high requirements on processors. Moreover, the module capacitor balance is challenging because the sorting time is too long when the traditional sorting algorithm for voltage balance is used. To solve the above issues, a digital implementation scheme of flexible power control strategy for three-phase to single-phase MMC-ACTPS system based on field programmable gate array (FPGA), which has sufficient I/O resources, has been proposed. Due to the parallel execution characteristics of the FPGA, the execution time of the controller and the modulator can be greatly reduced compared with a digital signal processor (DSP) + FPGA or DSpace. In addition, an improved sorting algorithm is proposed to reduce the sorting time and the implementation steps are analyzed. Finally, simulation and experimental results are presented to demonstrate the effectiveness and correctness of the proposed control strategy.

金星火山和气候探测任务（Venus Volcano Imaging and Climate Explorer，VOICE）聚焦金星火山与热演化历史、水与板块运动、内部结构和动力学、气候演化和生命信息探索等重大科学问题，提出采用极化合成孔径雷达（Polarimetric Synthetic Aperture Radar，PolSAR） 、下视与临边结合的微波辐射探测仪（Microwave Radiometric Sounder，MWRS）和紫外–可见–近红外多光谱成像仪（Ultraviolet-Visible-Near Infrared Multispectral Imager，UVN-MSI）等三个先进的有效载荷，在350 km圆轨道上对金星全球表面和大气联合探测。 PolSAR将对金星全球表面进行高分辨多极化雷达成像；MWRS将对金星全球云下大气的热力结构和化学组成，云中可能的宜居环境及与生命相关大气成分进行探测；UVN-MSI则实现大气全貌成像、表面光谱成像和闪电检测。通过多种先进探测载荷和技术手段的结合，VOICE任务将揭示金星构造热演化历史和超温室效应机理，探索其宜居性和生命信息。VOICE任务的实施将实现国际金星研究探索中许多“零”的突破，为理解行星宜居性和太阳系演化提供极为关键的观测支持，对提升中国在国际深空探测与空间科学研究中的地位产生重大影响。

With the advantages of low power consumption and high stability, chirp transform spectrometer (CTS) has become a powerful tool widely used in spectrum analysis today. In recent years, compared with other spectrum analyzers, CTS is limited by the lack of bandwidth, which severely restricts its application and development. In this article, a CTS system with a wide bandwidth is proposed. The chirp signal with 2 GHz bandwidth is generated by DAC and multiplier, and its dispersion characteristics are matched with a 1 GHz bandwidth surface acoustic wave (SAW) filter to build a spectrum analyzer with an analysis bandwidth of 1 GHz. Experimental results show that the system frequency resolution can reach up to 102 kHz, which is very close to the theoretical value (100 kHz).

基于南京电子器件研究所砷化镓工艺线,自主完成了750～1100 GHz全频带三倍频器以及中心频率为1030 GHz的低损耗二次谐波混频器的研制.为了提升模块的性能,将传统的场路结合的设计方法进行了扩展,引入器件的参数优化,并建立起两者互为反馈的关系,从而达到整个设计过程的闭环.研制出的单片电路厚度为3μm,并通过梁氏引线支撑悬置于腔体结构中.测试结果表明宽带倍频器在790～1100 GHz频率范围内输出功率为-23～-11 dBm.以上述倍频源作为射频信号对二次谐波混频器进行测试,在1020～1044 GHz频率范围内变频损耗优于17.5 dB,在1030 GHz处测得的最小变频损耗为14.5 dB.

The design, fabrication and measurement of a 2 × 2 local oscillator beam divider for pumping a hot electron bolometer based heterodyne array at 1.37 THz is presented. The WR0.65 rectangular waveguide-based H -plane and E -plane junctions are used to construct the feeding network. The divider comprises two 400- $\mu $ m thick silicon wafers with multilayer deep reactive-ion etching micromachined circuits, and a Pickett–Potter horn array manufactured in aluminum (AI) using computer numerical control machining. The two silicon plates and the AI plate were assembled with a special process using multilayer stacking technology to ensure an assembling misalignment lower than 10 μm. The radiation patterns of the beam divider are measured at 1.34 THz and 1.37 THz and compared to simulations. This is the first prototype of the multilayer stacked waveguide-based 2 × 2 beam divider at 1.37 THz ever fabricated.

To reduce the difficulty of local oscillator, a 1.4 THz fourth-harmonic mixer is proposed in this paper. The linear and nonlinear circuits are analyzed using finite element method and harmonic balance method respectively. Simulation result shows that the conversion loss is below 16.3 dB from 1400 GHz to 1480 GHz with 8mW Local Oscillator power at 365 GHz.

Platelets corrugated horn is a promising technology for their scalability to a large corrugated horn array. In this paper, we present the design, fabrication, measurement and uncertainty analysis of a wideband 170-320 GHz platelet corrugated horn that features with low sidelobe across the band (<-30 dB). We also propose an accurate and universal method to analyze the axial misalignment of the platelets for the first time. It is based on the mode matching (MM) method with a closed-form solution to off-axis circular waveguide discontinuities obtained by using Graf addition theorem for the Bessel functions. The uncertainties introduced in the fabrication have been quantitatively analyzed using the Monte Carlo method. The analysis shows the cross-polarization of the corrugated horn degrades significantly with the axial misalignment. It well explains the discrepancy between the designed and the measured cross-polarization of platelets corrugated horn fabricated in THz band. The method can be used to determine the fabrication tolerance needed for other THz corrugated horns and evaluate the impact of the corrugated horn for astronomical observations.

Based on the GaAs process of Nanjing electronic devices institute,a 750 similar to 1 100 GHz tripler and a low loss 1 030 GHz sub-harmonic mixer have been completed. To improve the performance of the module,the parameter optimization of the device is introduced in the traditional design method of field circuit combination,and the mutual feedback relationship is established. Therefore,the whole design process establishes the closed-loop. The 3 mu m thick monolithic circuit is supported in the cavity structure by using beam lead. The measured result shows that the output power of the broadband frequency multiplier is - 23 similar to -11 dBm in the frequency range of 790 similar to 1 100 GHz. Using the above-mentioned frequency multiplier source as the RF signal to test the sub-harmonic mixer,the conversion loss is better than 17. 5 dB in the frequency range of 1 020 similar to 1 044 GHz,and the minimum conversion loss is 14. 5 dB at 1 030 GHz.

Compared with Gallium Arsenide material, GaN device has better power endurance characteristics, and hence has great potential in the development of high power source. This paper proposes a heterojunction structure of GaN Schottky diode to improve the electron mobility of the device, and the cut-off frequency is over 250 GHz. Furthermore, a 120 GHz doubler is designed based on the proposed device. The simulated result shows that the conversion efficiency reaches 15% when the input power is 1 W.

A sub-harmonic monolithic mixer with a center frequency of 0. 825 THz is developed based on GaAs monolithic microwave integrated circuit technology. The parasitic parameters of the anti-parallel Schottky diode at the terahertz frequency are analyzed to improve the circuit design. The monolithic circuit is suitable for terahertz devices with the characteristics of high integration and little fabrication deviation. Meanwhile, the beamlead circuit is used to reduce the loss of substrate and installation position offset. Measured results show that the single-sideband (SSB) conversion loss of the mixer is lower than 33 dB in the frequency range 0. 81 similar to 0. 84 THz, and the minimum SSB conversion loss is 28 dB.

A high voltage responsivity detector in G‐band is designed in this paper. Different grounding models for the terahertz detector are analyzed and designed. Gold wire grounding design is superior to traditional grounding designs, which reduce the influence caused by the doping concentration, position and thickness error of conductive adhesive. Detectors are based on the Virginia Diodes Inc G‐band zero‐bias Schottky diode with low zero‐bias junction capacitance. The voltage responsivity test result of the gold wire grounding detector is about 1800 mV/mW in 210–220 GHz. The development of the detector provides the device basis for the realization of a terahertz focal plane imaging system.

In this article, we review the terahertz (THz) dielectric transmission lines in recent decade. Moreover, the developed special measurement technologies for measuring the THz dielectric transmission lines are introduced. Final, the various application scenarios of the THz dielectric transmission lines are presented.