毫米波和亚毫米波技术在军事上的应用

本文叙述了毫米波和亚毫米波系统的固有特点、军事价值和发展情况.讨论了毫米波和亚毫米波技术可能的军事应用,包括:目标捕获、通信、制导武器、波束武器、导航、火控和电子战.鉴于目前进展和各项发展计划,作者认为,毫米波和亚毫米波系统在九十年代将形成重大电子威胁.本文最后讨论了毫米波和亚毫米波技术的发展趋势.     

Millimeter-Wave Imaging Sensor

A scanning 3-mm radiometer system has been built and used on a helicopter to produce moderate-resolution (0.5°) images of the ground. This millimeter-wave sensor can be used for a variety of remote-sensing applications and produces images through clouds, smoke, and dust when visual and IR sensors are not usable. The system is described and imaging results are presented.     

Through-the-Wall Surveillance With Millimeter-Wave LFMCW Radars

The use of millimeter-wave radars allows a weight and size reduction of circuits and antennas, which is an important characteristic for Through-the-Wall Surveillance (TWS) applications. Furthermore, when using the millimeter-wave band, a large amount of bandwidth can be easily transmitted, given that the relative bandwidth is smaller. This leads to a high range resolution that allows for the discrimination of several targets that are very close in range, e.g., inside a room. The azimuth resolution is also improved due to the availability in this band of directive antennas with small dimensions. This paper studies the feasibility of using a millimeter-wave linear frequency-modulated continuous-wave radar in a TWS application. A TWS experiment in a real scenario has been done to demonstrate the validity of the theoretical analysis.      

Stereoscopic Passive Millimeter-Wave Imaging and Ranging

This paper presents the first stereoscopic range measurements at a wavelength of 3.3 mm and discusses the accuracy of this new method. The synthesis of passive millimeter-wave imaging and stereoscopy combines the advantages of both principles, naturally looking high-contrast images and superior poor-weather performance (compared to visible and infrared wavelengths), as well as the passive ranging capability. Our setup using two antennas with a half-power beamwidth (HPBW) of 0.9$^circ$and a stereoscopic baseline of 1.15 m allows ranging with an accuracy of$approxhbox10hbox%$up to a distance of$approx$300 m. The range resolution improves with increasing stereoscopic baseline, lower radiometer noise, narrower antenna beams, and higher scene contrast. For scenes with sufficient contrast, the directional resolution is considerably better than the antenna HPBW. Thus, massive oversampling of the scene in the plane of the stereoscopic baseline is required. For our setup, an oversampling factor of 36 is optimal. Since additional ranging errors result from nonstationary scenes, fast scanning imagers should be applied.     

A Versatile Millimeter-Wave Imaging System

A new millimeter-wave imaging system has been assembled at the Naval Research Laboratory and flight-tested using the NASA/ Wallops C-54 aircraft. The system incorporates an oscillating mirror and interchangeable radiometer units making it particularly adaptable to variations in its operational frequency, polarization, and angular resolution. Flight tests of the system have been conducted at 90 GHz and simultaneously at 22 and 31 GHz using a dual frequency radiometer. The imaging system and data processing are described and some of the initial flight test results at 90 GHz are presented.     

一种改进的毫米波图像超分辨率重建算法

针对毫米波成像时,由于天线孔径受限使得获取的图像空间分辨率很低、高频信息损失严重的问题,提出一种改进的非凸集投影超分辨算法。该算法以非凸集阈值收缩迭代算法(Non-convex Shrinking Iteration,NCSHI)为基础,采用具有平移不变特性的双树复数小波作为稀疏基,引入了两步迭代过程,有效地利用了前两次的迭代信息。实验仿真结果表明,该算法有效地改善了伪吉布斯效应,收敛速度更快,具有良好的超分辨性能。     

Active Sparse-Aperture Millimeter-Wave Imaging Using Digital Correlators

Millimeter-wave imaging systems have desirable characteristics, particularly in their ability to form images of objects obscured by various barrier materials. However, the relatively long wavelength of the millimeter-band implies a penalty in angular resolution, usually compensated using large-aperture systems. Synthesized apertures provide the desired collecting area with a reduced number of discrete detectors. In this research we designed, built, and characterized the performance of a prototype sparse-aperture imaging system, utilizing an active 94 GHz source. Discrete sensors were used to sample the radiation field backscattered from the object. The signals were down-converted using heterodyne receivers with digital in-phase and quadrature detection. Signal correlations were performed using the digitized data sets to reconstruct millimeter-wave images. Image-quality performance was experimentally evaluated using four different non-redundant aperture configurations, with good agreement to the theoretical expressions. The feasibility of digital electronic-focusing correction was also demonstrated over an object range from 400 to 700 mm.     

Smart Video Surveillance for Proactive Security

This article presents an overview of smart video surveillance technologies and their application to homeland security and police monitoring.     

Y Dielectric Waveguide for Millimeter- and Submillimeter-Wave

A new type of waveguide structure having Y cross section is presented and investigated theoretically. This waveguide is suitable for millimeter- and submillimeter-wave and facilitates supporting the waveguide with little field disturbance. Numerical results are presented for the dispersion characteristics, the transmission losses, and the power distributions using the generalized telegraphist's equations. The transmission characters of a triangular dielectric waveguide are also investigated as a special case.     

A Low-Power Linear SiGe BiCMOS Low-Noise Amplifier for Millimeter-Wave Active Imaging

This letter presents a low-power linear and wideband two-stage millimeter-wave low-noise amplifier (LNA) fabricated in a low-cost 0.18 $mu{rm m}$ SiGe BiCMOS technology. Design techniques utilized to optimize the gain and NF and to achieve high linearity and wideband at W-band are addressed. The LNA achieves a peak power gain of 14.5 dB at 77 GHz with a 3 dB bandwidth of 14.5 GHz from 69 to 83.5 GHz. The measured NF is 6.9 dB at 77 GHz and is lower than 8 dB from 64 to 81 GHz. Both input and output return losses are better than 11 dB and 17 dB at 77 GHz, respectively. The measured input 1 dB compression point is $-$11.4 dBm at 77 GHz with low power consumption of only 37 mW.      

Single-Chip W-band SiGe HBT Transceivers and Receivers for Doppler Radar and Millimeter-Wave Imaging

This paper presents the first single-chip direct-conversion 77-85 GHz transceiver fabricated in SiGe HBT technology, intended for Doppler radar and millimeter-wave imaging, particularly within the automotive radar band of 77-81 GHz. A 1.3 mm times 0.9 mm 86-96 GHz receiver is also presented. The transceiver, fabricated in a 130 nm SiGe HBT technology with f_T/f_MAX of 230/300 GHz, consumes 780 mW, and occupies 1.3 mm times 0.9 mm of die area. Furthermore, it achieves 40 dB conversion gain in the receiver at 82 GHz, a 3 dB bandwidth extending from 77 to 85 GHz at 25degC, and covering the entire 77-81 GHz band up to 100degC, record 3.85 dB DSB noise figure measured at 82 GHz LO and 1 GHz IF, and an IP_1dB of -35 dBm. The transmitter provides + 11.5 dBm of saturated output power at 77 GHz, and a divide64 static frequency divider is included on-die. Successful detection of a Doppler shift of 30 Hz at a range of 6 m is shown. The 86-96 GHz receiver achieves 31 dB conversion gain, a 3 dB bandwidth of 10 GHz, and 5.2 dB DSB noise figure at 96 GHz LO and 1 GHz IF, and -99 dBc/Hz phase noise at 1 MHz offset. System-level layout and integration techniques that address the challenges of low-voltage transceiver implementation are also discussed.     

2-D Acoustic Phase Imaging With Millimeter-Wave Radiation

We report on 2-D acoustic phase imaging with millimeter-wave radiation for locating concealed objects. Active adaptation of the imaging interferometer provides enhanced images. We demonstrate that the method allows for finding metallic as well as dielectric materials. Even objects having similar optical properties as the background can be located.      

Passive Millimeter-Wave Imaging Module With Preamplified Zero-Bias Detection

An analytical model and supporting measured data are presented for a preamplified $W$-band radiometer with a zero-bias detector appropriate for commercial millimeter-wave imaging cameras. Basic radiometer parameters, including RF bandwidth, are computed directly from simple low-frequency measurements and compare well with those obtained from RF measurements. A detailed analytical model shows how radiometer performance depends on internal component parameters, such as low-noise amplifier gain, noise factor, reflection coefficient, detector responsivity, etc. The measurements suggest that performance is sufficient for operation without a Dicke switch or mechanical chopping. A measured noise equivalent temperature difference of 0.45 K was obtained, assuming a single sensor is scanned across a focal plane, forming 32 pixels with 3.125-ms integration time per pixel. This sensitivity is considered sufficient by commercial manufacturers to obtain quality images in low-contrast (e.g., indoor) environments.      

安防监控热门方案评介

近年来,中国视频监控市场受到“平安城市”项目、奥运安防项目以及各地、各行业安防项目需求加速增长等因素的刺激和拉动．整体市场规模迅速扩大。2007年．中国视频监控市场的总体规模达181亿美元．且未来将持续而稳定的快速发展。政府、金融和电信仍是视频监控主要的应用领域,分别占了总体市场规模的29．4％．20．2％和14．7％。     

Improved Two-Dimensional Millimeter-Wave Imaging for Concealed Weapon Detection Through Partial Fourier Sampling

Active millimeter-wave imaging based on synthetic aperture focusing offers certain unique and practical advantages in nondestructive testing applications. Traditionally, the imaging for this purpose is performed through a long procedure of raster scanning with a single antenna across a two-dimensional grid, leading to a slow, bulky, and expensive scanning platform. In this paper, an improved bistatic structure based on radial compressive sensing is proposed, where one fixed transmitter antenna and a linear array of receiving antennas are used. The main contributions of this paper are (a) reducing the scanning time, (b) improving the output quality, and (c) designing an inexpensive setup. These improvements are the result of the underlying proposed simpler scanning structure and faster reconstruction process.     

光纤视频安全监视系统

自“911”事件以来,世界发生的变化是显而易见的,每一个公众集中的地点都要提高安全性。飞机场、火车站、校园、工业建筑、娱乐场所和公园等公共场所现在都需要安装安全检测和监视系统。要求监视系统能提供24小时全天候监视能力以防止可能出现的险情和监控对私人区域的侵入,这是对安全系统设计工程师提出的严肃挑战。安全和监控最直接的解决办法是在所有关键位置都安装电视摄像机,把视频信号集中输出到中央监控室。在中央监控室,一个人的眼睛就能监控许多地点。到处分布的几千架监视用电视摄像机实际上复盖了每一个公众场所。由于对安全需求…     

主动式近距离太赫兹人体安检技术分析*

主动式近距离太赫兹成像技术在人体安检领域已经有了广泛的应用,目前主要有平面扫描、圆柱扫 描、扇束扫描三种成像模式。对此三种成像模式的成像原理进行了介绍,对比了不同成像模式的优缺点,同时分析 了影响成像质量的因素,从分辨率、信噪比和伪影去除三个方面探讨了提高图像质量的方法,为研发新型主动式近 距离太赫兹人体安检设备提供了参考。     

Terahertz Spectroscopy and Imaging for Defense and Security Applications

Terahertz (THz) radiation, which occupies a relatively unexplored portion of the electromagnetic spectrum between the mid-infrared and microwave bands, offers innovative sensing and imaging technologies that can provide information unavailable through conventional methods such as microwave and X-ray techniques. With the advancement of THz technologies, THz sensing and imaging will impact a broad range of interdisciplinary fields, including chemical and biological detections and identifications. In particular, THz radiation offers the opportunity for transformational advances in defense and security. Recent work shows that THz technologies are promising for the standoff detection and identification of explosive targets.