The US Army Combat Capabilities Development Command Army Research Laboratory is developing a dualband, full-polarization, side-looking synthetic aperture radar using an RF system-on-a-chip for the detection of landmines. The system employs two separate front-ends to operate in the bands from 0.5 to 1.8 GHz and from 2.1 to 3.8 GHz. An antenna array is set up with two transmitters (one vertical and one horizontal) and two receivers (one vertical and one horizontal) to enable fully-polarimetric operation. A continuous wave stepped-frequency waveform is employed, and each combination of polarizations is simultaneously transmitted and received. This system was tested at a desert site. The targets that were tested were remote anti-armor mine system landmines, M20 metal landmines, and VS2.2 plastic landmines. The targets are imaged under a number of emplacement scenarios so that imaging results address targets made of various materials at different orientations and ranges. Furthermore, obscured targets and buried targets are also investigated. The effect of antenna coupling and techniques for reducing this effect are discussed. Then, the imaging results for each target scenario is shown and analyzed. Imaging results between data from the two frequency bands are compared and the success of detection for different emplacements is analyzed.
Intermodulation radar is an established technique for locating electromagnetically-nonlinear junctions. For this type of radar, the probe consists of multiple simultaneous frequencies, usually two tones of equal amplitude. The multiple frequencies illuminate the target, mix with each other, and generate integer sums and differences of the original transmitted tones. This work studies a variation on the intermodulation-radar technique. Some targets, such as AM/FM transmitters, emit radio frequencies without being actively probed; thus, some collections of (powered) nonlinear junctions generate at least one internal tone which might be mixed with an externally-applied probe tone. This internal-external mixing is referred to as “carrier modulation,” where the carrier is associated with the target and its modulation is induced by the transmit probe. This paper documents an experiment conducted using a transverse electromagnetic cell: contactless excitation of carrier modulation from active nonlinear junctions. Data recorded from two radio transmitters indicate that, for this internal-external mixing technique, a reduction in transmit power results in less of a reduction in received power compared to traditional intermodulation radar.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.