W-band multibeam scanning radiometric system for contraband detection applications

Abstract

Due to rather low absorption in fabric materials of clothes, millimeter band electromagnetic waves can serve for security and customs services as additional source of operative and remotely obtained information concerning any irrelevant "discontinuities" located on human body under clothes, likewise about dimensions and types of such discontinuities. These peculiarities could essentially reduce number of persons subjected to additional personal control and, as a result, essentially raise efficiency of customs examination as a whole [ 1,2]. Based on reception of person's own heat radiation the method of passive (radiometric) supervision should be expected the most prospective because not connected with generation at public places any additional high intensity electromagnetic fields capable to take negative effect both on inspected people and customs staff.In transformation to considering task, the main problem need to be solved at radiometric supervision system design is operative image generation at the distances about 3-5 m with sufficiently high quality at spatial and radiometric resolution. This problem can be resolved only by force of system engineering under multichannel (multi-beam) scheme with parallel or parallel-sequent space observation. One possible way observation scheme design may be utilization the method of frequency beam separation by splitting antenna pattern on some (N) contiguous friend to friend beams along horizontal axis with their joint focusing on the observation plane and synchronous electro-mechanical scanning this combined pattern along vertical axis in order to spatial domain review. In contrast to well-known methods of space observations by a matrix of receivers, the frequency beam separation method could be realized and parallel-sequential image generation is possible with only one unique ultrahigh-frequency receiving device in the system. That could considerably reduce complicity and cost of the system -parameters significant for wide promotion this method to practice.. Within the framework of conjoined project of the Joint-Stock Company "Scientific & Productive Enterprise "SATURN"" and IRE NASU at development of prospective supervision systems for applications at security and customs services, an experimental sample of W-band multi-beam scanning radiometric system for people visualization is developed [l]. Block diagram of the system is presented on Figure 1. Main system parameters described in Table 1.Open electrodynamic structure based on the principles of volume-to-surface electromagnetic waves conversion and included disk shape metal diffraction grating and dielectric waveguide is used as receiving aperture, which technically implemented at the scanning antenna with electromechanical beam control [3]. Due to specific dispersing properties inherent to this electrodynamic structure and utilization the principles of frequency beam splitting, 2N (N = 16) independent antenna beams are formed along horizontal coordinate (azimuth axis) by separating full operating frequency band Af on...

Compact MMW-band Planar Diffraction Type Antennas for Various Applications

“…Figure 8 shows the main view of the W-band scanning ADR constructed with a single-tier waveguide circuit, when the PDG is performing as a metal disk, which has ability to oscillate around the rotation axis using a step-motor drive, and which provides a mode of scanning of the beam-pattern in the vertical plane. Such an antenna was tested in the 32 beam-forming mode in the W-band passive imaging system with formation of 2 images per second in the presence of only one moving element in the system -namely, the PDG in the form of a disk [25]. Figure 9 shows the main view of Ka-band planar ADR with aperture size 18 cm × 200 cm tested as an antenna for radar station destined for airport's land area observation [26,27].…”