Analysis of RF imaging applications at frequencies over 100 GHz

Wallace, H. Bruce

doi:10.1364/ao.49.000e38

Cited by 62 publications

(23 citation statements)

References 15 publications

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“…In analyses of sub-millimeter radar imaging for concealed threat detection [9] [1], it is of course the scattering properties of the abdomen and back that are most relevant. The fact that our measurements show slightly higher scattering from these sites than from the volar forearm seems to be consistent with their reported roughness levels [8] lying near the middle of the observed range (versus lower levels for the forearm).…”

Section: Discussionmentioning

confidence: 99%

“…The bidirectional scattering distribution function (BSDF) and the area normalized bidirectional radar cross section (σº) are related concepts and are needed to determine detection threshold levels in radars and other active imagers [1,9]. Since our measurement geometry is reflective, BSDF is equivalent to bidirectional reflectance distribution function (BRDF).…”

Section: Introductionmentioning

confidence: 99%

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650 GHz bistatic scattering measurements on human skin

2014

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Many groups are developing submillimeter cameras that will be used to screen human subjects for improvised explosive devices (IEDs) and other threat items hidden beneath their clothing. To interpret submillimeter camera images the scattering properties, specifically the bidirectional scattering distribution function (BSDF) must be known. This problem is not trivial because surfaces of man-made objects and human skin have topographic features comparable to the wavelength of submillimeter radiation -thus simple, theoretical scattering approximations do not apply. To address this problem we built a goniometer instrument to measure the BSDF from skin surfaces of live human subjects illuminated with a beam from a 650 GHz synthesized source.To obtain some multi-spectral information, the instrument was reconfigured with a 160 GHz source. Skin areas sampled are from the hand, interior of the forearm, abdomen, and back. The 650 GHz beam has an approximately Gaussian profile with a FWHM of approximately 1 cm. Instrument characteristics: angular resolution 2.9º; noise floor -45 dB/sr; dynamic range > 70 dB; either s or ppolarization; 25º ≤ bidirectional-scattering-angle ≤ 180º; The human scattering target skin area was placed exactly on the goniometer center of rotation with normal angle of incidence to the source beam. Scattering power increased at the higher frequency. This new work enables radiometrically correct models of humans.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

650 GHz bistatic scattering measurements on human skin

2014

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“…As described in Sect. 19.2, since passive systems rely on ambient black- body illumination they suffer from atmospheric and clothing attenuation more than their active counterparts [67].…”

Section: Passive Stand-off Imaging Systemsmentioning

confidence: 99%

Millimeter-Wave and Terahertz Imaging in Security Applications

Luukanen

Appleby

Kemp³

et al. 2012

Springer Series in Optical Sciences

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The relatively short wavelength of mm-wave and THz radiation coupled with good transmission through many dielectric materials allows images to be formed of concealed objects. This chapter gives an overview of the detectors, their associated circuitry, and system developments over the past 10 years, focussing on personnel security screening. We will discuss the phenomenology of imaging at these wavelengths, introduce the reader to the basic architectures being used and developed for image forming instruments, show examples of systems, and also discuss the feasibility of spectroscopic THz imaging for security screening applications.

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“…Millimeter-wave imaging is a subject of both long and increasing interest [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. This interest is driven by the capabilities of radiation in this spectral region to penetrate covering obstructions and to do so with enough angular resolution for useful imaging.…”

Section: Introductionmentioning

confidence: 99%

Range resolved mode mixing in a large volume for the mitigation of speckle and strategic target orientation requirements in active millimeter-wave imaging

et al. 2015

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In spite of many reports of active millimeter-wave imaging in the literature, speckle and requirements for cooperative target orientation significantly reduce its practical usefulness. Here we report a new technique, range resolved mode mixing (RRMM), which significantly mitigates both of these issues. It also provides a three-dimensional (3D) image. RRMM accomplishes this by combining multimode illumination (which eliminates the requirement for cooperative target orientation) with range resolution (which provides statistical independence of speckle patterns for averaging and the 3D image). The use of a 5W extended interaction klystron amplifier results in large signal margins in the 50 m scale atrium of the Physics Department at Ohio State University. It appears that there are a number of scenarios out to a range of 1 km for which this approach is useful to provide 3D images, with minimal speckle, and no requirement for cooperative target orientation.

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Analysis of RF imaging applications at frequencies over 100 GHz

Cited by 62 publications

References 15 publications

650 GHz bistatic scattering measurements on human skin

650 GHz bistatic scattering measurements on human skin

Millimeter-Wave and Terahertz Imaging in Security Applications

Range resolved mode mixing in a large volume for the mitigation of speckle and strategic target orientation requirements in active millimeter-wave imaging

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