Ka波段厚窗片盒形窗的研究

提出了一种厚窗片的盒形窗设计,其窗片厚度约为传统盒形窗窗片厚度的三倍,可以提高封接的可靠性.计算机模拟结果和样品测试证实这种窗的反射系数在27.5 GHz-40 GHz内可以做到小于0.2,在中心频段可以做到小于0.1.计算表明,在W波段,这种窗仍然性能优良.此外,较厚的窗片更容易保证气密.     

0.14 THz折叠波导行波管盒型窗设计与制作

研究用于0.14 THz 折叠波导行波管的盒形窗结构,采用三维模拟软件 HFSS 进行计算与优化,设计出基于蓝宝石窗片的盒型窗结构.分析了结构参数对盒形窗电压驻波比的影响,主要结构参数在±0.01 mm范围变化时,盒形窗电压驻波比仍然低于1.2,保证零件加工的可行性.装配完成盒形窗测试结构,冷测结果显示,在0.135 THz~0.145 THz范围内衰减系数为0.7 dB左右,满足整管要求.     

0.22 THz折叠波导行波管盒型窗设计及实验

针对0.22 THz 折叠波导行波管设计了一款高频输入输出结构-盒型窗,并对其进行了理论分析和数值计算,通过 CST2010微波工作室和 Ansoft HFSS11进行模拟仿真验证。这种盒型窗不但降低了加工焊接难度,而且保证了较大带宽。本文得到了0.02 THz带宽,在0.21 THz~0.23 THz范围内反射系数都小于0.08。最终通过加工和实验测试对盒型窗进行了验证,实验测试和理论计算基本一致,满足了0.22 THz折叠波导行波管的需要。     

工艺参数影响的D波段行波管盒型窗分析

由于尺寸较小,D波段行波管盒型窗对各个参数的影响较为敏感,因此使用CST软件对蓝宝石窗片的盒形窗进行优化设计。从各个工艺参数出发,对窗片金属化层的内径和厚度,以及焊料层的厚度和圆波导高度等的影响进行了软件仿真分析,得到了优化后最佳值为10GHz的带宽,即在133GHz144GHz范围内,驻波比低于1．2。最后加入整个慢波结构和衰减瓷的模型中进行计算,得到了驻波比低于1．4的结果,满足整管指标要求。     

一种新型Ka波段盒型窗

本文介绍了一种新型Ka波段盒型窗,并利用HFSS进行仿真优化,得到在32.6～39.6 GHz带宽内S11低于-20dB的无鬼模振荡输出,与标准的半波长厚度的介质窗片相比,其与圆波导接触面积较大,更有利于散热。     

一种截止式圆波导盒形窗的研究

提出了具有截止圆波导的盒形窗的设计方法,使得盒形窗的尺寸大大缩小,结构紧凑,极大地拓宽了盒形窗的频带。针对这种新型盒形窗的主要结构参数,利用HFSS得出了各个参数对其驻波系数的影响,从而找到了几种较好的结构尺寸,使得它们可以应用在较宽的工作频带,最后对比了计算值、模拟值以及实测值的数据,三者符合良好。     

InP基共振隧穿二极管太赫兹振荡器的设计与实现

利用InP基共振隧穿二极管（RTD）和加载硅透镜的片上天线设计实现了超过1 THz的振荡器。采用Silvaco软件对RTD模型进行仿真研究,分析了不同发射区掺杂浓度、势垒层厚度、隔离层厚度以及势阱层厚度等对器件直流特性的影响规律。对研制的RTD器件直流特性测试显示：峰值电流密度Jp为359.2 kA/cm²,谷值电流密度Jv为135.8 kA/cm²,峰谷电流比PVCR为2.64,理论计算得到的器件最大射频输出功率和振荡频率（fmax）分别为1.71 mW和1.49 THz。利用透镜封装的形式对采用Bow-tie片上天线和RTD设计的太赫兹振荡器进行封装,测试得到振荡频率超过1 THz,输出功率为2.57μW,直流功耗为8.33 mW,是国内首次报道超过1 THz的振荡器。     

Al_2O_3陶瓷窗片在毫米波盒形窗中的微波性能模拟及其封接残余应力模拟评估

利用CST MWS软件,模拟了用于毫米微波管高功率盒形输能窗的Al2O3陶瓷的微波特性,模拟得出,陶瓷窗片的厚度和介电常数对窗片驻波比有一定的影响,模拟计算和实验测试结果具有较好的一致性;同时,利用ANSYS软件对该Al2O3陶瓷在输能窗中的封接残余应力进行了模拟评估,并和薄壳理论外套封结构的解析计算进行了对比。     

一种基于微\纳米加工技术的新型太赫兹片上螺旋天线

给出了一种基于微\纳米加工技术的3D片上天线结构,天线工作频率为1.5THz。该天线结构包含圆柱形金属螺旋和衬底上的微带馈线两个部分。所提出的天线结构可以在单片晶圆上利用微\纳米加工技术实现,且方便与系统其它部分的电路集成于同一芯片内部。天线在1.4~1.6THz频段内具有很高的增益（11 dBi）和很宽的工作带宽（200GHz）,非常适合应用于太赫兹通信系统。     

Al203陶瓷窗片在毫米波盒形窗中的微波性能模拟及其封接残余应力模拟评估

利用CST MWS软件,模拟了用于毫米微波管高功率盒形输能窗的Al2O3陶瓷的微波特性,模拟得出,陶瓷窗片的厚度和介电常数对窗片驻波比有一定的影响,模拟计算和实验测试结果具有较好的一致性;同时,利用ANSYS软件对该Al2O3陶瓷在输能窗中的封接残余应力进行了模拟评估,并和薄壳理论外套封结构的解析计算进行了对比.     

CMOS-Compatible Room-Temperature Rectifier Toward Terahertz Radiation Detection

In this paper, we present a new rectifying device, compatible with the technology of CMOS image sensors, suitable for implementing a direct-conversion detector operating at room temperature for operation at up to terahertz frequencies. The rectifying device can be obtained by introducing some simple modifications of the charge-storage well in conventional CMOS integrated circuits, making the proposed solution easy to integrate with the existing imaging systems. The rectifying device is combined with the different elements of the detector, composed of a 3D high-performance antenna and a charge-storage well. In particular, its position just below the edge of the 3D antenna takes maximum advantage of the high electric field concentrated by the antenna itself. In addition, the proposed structure ensures the integrity of the charge-storage well of the detector. In the structure, it is not necessary to use very scaled and costly technological nodes, since the CMOS transistor only provides the necessary integrated readout electronics. On-wafer measurements of RF characteristics of the designed junction are reported and discussed. The overall performances of the entire detector in terms of noise equivalent power (NEP) are evaluated by combining low-frequency measurements of the rectifier with numerical simulations of the 3D antenna and the semiconductor structure at 1 THz, allowing prediction of the achievable NEP.     

Tunable CW-THz system with a log-periodic photoconductive emitter

A tunable CW-THz system with a LTG-GaAs based THz source, which consists of an interdigitated finger photomixer integrated log-periodic antenna, is presented. The performance is compared against that of several other broadband CW-THz systems with LTG-GaAs based emitters, incorporating bow-tie and log-spiral antenna geometries. This comparison shows that our maximum output THz power level is within an order of magnitude of that of the state-of-the-art.     

Terahertz radiation of a butterfly-shaped photoconductive antenna (invited)

The terahertz(THz) far-field radiation properties of a butterfly-shaped photoconductive antenna (PCA) were experimentally studied using a home-built THz time-domain spectroscopy(THz-TDS) setup. To distinguish the contribution of in-gap photocurrent and antenna structure to far-field radiation, polarization-dependent THz field was measured and quantified as the illuminating laser beam moved along the bias field within the gap region of electrodes. The result suggests that, although the far-field THz radiation originates from the in-gap photocurrent, the antenna structure of butterfly-shaped PCA dominates the overall THz radiation. In addition, to explore the impact of photoconductive material, radiation properties of butterfly-shaped PCAs fabricated on both low-temperature-grown GaAs(LT-GaAs) and semi-insulating GaAs(Si-GaAs) were characterized and compared. Consistent with previous experiments, it is observed that while Si-GaAs-based PCA can emit higher THz field than LT-GaAs-based PCA at low laser power, it would saturate more severely as laser power increased and eventually be surpassed by LT-GaAs-based PCA. Beyond that, it is found the severe saturation effect of Si-GaAs was due to the longer carrier lifetime and higher carrier mobility, which was confirmed by the numerical simulation.     

光生等离子体栅扫描天线研究进展

毫米波和太赫兹(THz)波天线扫描技术已经成为当前电磁领域研究的热点,光生等离子体栅(PIPG)扫描天线技术作为一种低成本的快速扫描技术为操控毫米波和THz波提供了新的方法和思路。本文将对PIPG扫描天线的原理、结构、效率和方向图等主要研究进展做详细的论述,并且对PIPG扫描天线的研究意义和存在的主要问题进行讨论和展望,希望对PIPG扫描天线的研究和应用提供参考。     

单面金属波导太赫兹量子级联激光器的天线模型

太赫兹(THz)量子级联激光器(QCL)是理想的固态THz源,其出射光束的远场特性是THz QCL研究中重要的一部分。实验上,THz QCL的远场光斑常呈多瓣或环形结构,用一般的衍射理论难以解释,为此把激光器看成辐射天线,利用电磁场理论,推导了单面金属波导THz QCL辐射远场场分布和光强分布基本公式。对具有典型参数的THz QCL的远场分布进行了计算。数值结果表明：辐射远场光强分布是不对称的环形结构,且随着激光器的腔长变长,环逐渐变密。可见,THz QCL的天线模型给出了与实验观察一致的结果,说明天线模型更适合于THz QCL远场光束的分析。     

NOVEL TERAHERTZ PHOTOCONDUCTIVE ANTENNAS

The photoconductive (PC) antenna is a key device for the recent terahertz (THz) photonics based on laser-pumped generation and detection of THz radiation. In this paper we report on two new types of PC antennas: the Schottky PC antenna and the multi-contacts PC antenna. The former one is able to detect THz radiation intensity without the time-delay scan and useful for applications where spectroscopic information is not important, such as the THz intensity imaging. The latter one is useful for the polarization sensitive THz spectroscopy, such as the THz ellipsometry. The characteristic features of these new types of PC antennas are studied by using a THz time-domain spectroscopy system.     

Investigation of the antenna characteristics with the impact of hexagonal metamaterial

Antenna miniaturization is a typical trend in contemporary wireless systems, notably for current wireless technology, to meet multiband needs while preserving high transmission qualities. The terahertz (THz) regime is helpful in advanced applications and significantly impacts wireless technology. This paper proposes a double-layered hexagonal split ring resonator (HSRR) based on a microstrip patch antenna (MPA) and analyzes the simulated characteristics. The HSRR width is varied for different thickness “w” values and compares the analysis of with and without HSRR in the antenna. Due to the impact of metamaterials, the optimized antenna produces −44.02-dB return loss, 1.012 voltage standing wave ratio (VSWR), 6.47-dBi gain, and 4.78-dB directivity at 1.8-THz frequency. This proposed antenna is suitable for THz applications, which include high-speed data rate in wireless communication, bio-medical field, and THz spectrometer.     

Equivalent circuit model for a THz detector based on the double-electron layer tunneling transistor (DELTT)

An equivalent circuit model for the double-electron layer tunneling transistor (DELTT) integrated with an antenna is presented in this paper. This device is used basically for THz detection, and the antenna is used to efficiently couple THz radiation into the device for processing. Developing an equivalent circuit model is extremely helpful in matching the antenna to the device.     

Terahertz (THz) Frequency Sources and Antennas - A Brief Review

In this paper we review THz radiation properties, generation methods, and antenna configurations. This paper suggests some new class of antennas that can be used at THz frequency, like optical antennas or Carbon nanotube antennas. THz technology has become attractive due to the low energy content and nonionizing nature of the signal. This property makes them suitable for imaging and sensing applications. But at the same time detection and generation of THz signals has been technologically challenging. This paper presents a comparative study of the generation techniques for THz frequency signals giving emphasis to the some new techniques like Quantum Cascade lasers which has created significant research interest. The main aim for this study is to find out the materials suitable for fabricating THz devices and antennas, a suitable method for generation of high power at THz frequency and an antenna that will make THz communication possible.     

Room-Temperature Oscillation of Resonant Tunneling Diodes close to 2 THz and Their Functions for Various Applications

Compact and coherent source is a key component for various applications of the terahertz (THz) wave. We report on our recent results of THz oscillators using resonant tunneling diodes (RTDs). To achieve high-frequency oscillation, the electron delay time of RTD was reduced with a narrow quantum well and an optimized collector spacer thickness. Conduction loss at the air bridge connecting RTD and slot antenna, which works as a resonator and a radiator, was also reduced. By these structures, a fundamental oscillation up to 1.92 THz was obtained at room temperature. Theoretical calculation shows that an oscillation over 2 THz is further expected by improved structures of RTD and antenna. Using the offset slot antenna and two-element array configuration, high output power of 0.61 mW was obtained at 620 GHz. A direct intensity modulation of RTD oscillators up to 30 GHz, which is useful for high-speed wireless data transmission, was demonstrated. By the integration of a varactor diode, wide frequency sweep of 580–700 GHz in a single device and 580–900 GHz in a four-element array were also demonstrated. This result expands possible applications of RTD oscillators.