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Proceedings Paper

Geometrical configurations of unphased diffraction-limited antennas in passive millimetre-wave imaging systems for concealed weapon detection
Author(s): Roberto Serenelli
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Paper Abstract

This paper analyzes simple imaging configurations to scan a human body, suitable as passive or active millimetre-wave imaging systems for concealed weapon detection (CWD). The first cylindrical configuration allows a 360 degrees scan: N unphased diffraction-limited antennas each of size L are placed on a circular support surrounding the subject (allowing scanning in the horizontal plane with N non-overlapping independent beams), and this circle is mechanically displaced over the whole body height. An analytical formula gives the maximum obtainable spatial resolution for different dimensions of the circular scanning device and operating frequencies, and the number of receivers achieving this optimal resolution. Constraints to be taken into account are diffraction, the usable total length of the circle, and the full coverage by the N beams over the subject, which is modelled as a cylinder with variable radius, coaxial with the scanning circle. Numerical calculations of system resolution are shown for different operating microwave (MW) and millimetre-wave (MMW) frequencies; in order to study off-axis performances, situations where the subject is not coaxial with the scanning device are also considered. For the case of a parallelepiped to be imaged instead of a cylinder, a linear array configuration is analyzed similarly to the circular one. A theoretical study is carried out to design other curved arrays, filled with unphased diffraction-limited antennas, for the imaging of linear subjects with finer resolution. Finally, the application of such configurations is considered for the design of active imaging systems, and different system architectures are discussed.

Paper Details

Date Published: 8 December 2004
PDF: 12 pages
Proc. SPIE 5619, Passive Millimetre-Wave and Terahertz Imaging and Technology, (8 December 2004); doi: 10.1117/12.578461
Show Author Affiliations
Roberto Serenelli, Univ. of Florence (Italy)


Published in SPIE Proceedings Vol. 5619:
Passive Millimetre-Wave and Terahertz Imaging and Technology
Roger Appleby; J. Martyn Chamberlain; Keith A. Krapels, Editor(s)

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