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Project Summary
- A microwave radar is under development to achieve
imaging of moving and stationary targets through visually
opaque obstacles such as walls.
- Low-profile, broadband, and dual polarized antennas
are being designed to offer portability, achieve optimal
wall penetration, and provide high signal-to-clutter
ratio.
- Signal Processing methods are being developed to
enhance the signal-to-clutter ratio, improve
two-dimensional imaging resolution, distinguish targets of
interest from others, and obtain fast and simplified
implementations of the designed algorithms.
Hybrid techniques of antenna, design,
electromagnetic modeling, and signal
processing are used to achieve effective imaging of moving
and stationary objects through walls using microwave
frequencies. Through-wall microwave sensing can be used in
rescue missions, behind-the-wall target detection,
surveillance and reconnaissance, and even sensing through
smoke and dust, to name a few. Low-profile, broadband, and
dual polarized antennas are designed to offer portability,
achieve the required bandwidth for proper penetration and
resolution, and provide high signal-to-clutter ratios.
Electromagnetic modeling of these antennas and the wave
interaction with various types of walls and material is
performed using numerical methods such as the
Finite-Difference Time Domain technique, the Finite Element
Method, and the Method of Moments. Transmit and receive
antennas with dual polarization allows improved target
classification based on polarization properties and is
considered key to achieving system performance beyond that
obtained through range-Doppler processing.
The offerings of signal
processing techniques to the Through-wall microwave imaging
system lie in fast implementations, integration of the
advances in beamforming and array signal processing, signal
detection using modern and newly developed statistical
analysis algorithms. The objectives are to achieve real-time
target detection and classification, enlarged array aperture
for high-resolution direction finding and clutter removal,
and estimation of polarization parameters for target
identification. Increased effective aperture is accomplished
by using aperture synthesis schemes based on the coarray
formalism. Multiplexing the processing apparatus between two
small aperture systems can be used to synthesize a larger
array. Moving the small aperture system along a rail
coinciding with the horizontal axis of the plane in which
its elements are deployed is also a vehicle improved system
performance.
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