posted on 2014-02-03, 00:00authored byLorenzo Lo Monte, Danilo Erricolo, Francesco Soldovieri, Michael C. Wicks
Three extensions to radio-frequency (RF) tomography for imaging of voids under wide areas of regard are presented.
These extensions are motivated by three challenges. One challenge is the lateral wave, which propagates in proximity of
the air–earth interface and represents the predominant radiation mechanism for wide-area surveillance, sensing of denied terrain, or close-in sensing. A second challenge is the direct-path coupling
between transmitters (Txs) and receivers (Rxs), that affects the measurements. A third challenge is the generation of clutter by the unknown distribution of anomalies embedded in the ground.
These challenges are addressed and solved using the following strategies: 1) A forward model for RF tomography that accounts
for lateral waves expressed in closed form (for fast computation);
2) a strategy that reduces the direct-path coupling between any Tx–Rx pair; and 3) an improved inversion scheme that is robust
with respect to noise, clutter, and high attenuation. A finite difference
time domain simulation of a scenario representing close-in sensing of a denied area is performed, and reconstructed
images obtained using the improved and the classical models of RF tomography are compared.
Funding
This work was supported in part by the Air Force Research Laboratory under Contract
F33601-02-F-A581 and in part by the U.S. Department of Defense under Grant FA9550-05-1-0443.