Abstract
A Time-Reversal ( TR) imaging method for multiple targets that
incorporates fewer transmitters is suggested using temporal filtering
and Frequency Focusing (FF) matrices. This study is intended for the
detection of malignant breast tumors with minimal microwave radiation. A
couple of scenarios with two and four tumors are considered here. Using
only two transmitters and twelve receivers, we show that two tumors
could be detected in an inhomogeneous tissue breast. The results are
compared with conventional TR Multiple Signal Classification method
(MUSIC), which requires more transmitters. It is shown that several
well-resolved tumors that exceed transmitters could be detected by
subregion Spatio-Temporal Filtering (SSTF). In our proposed method, we
used the orthogonal subspace instead of the signal subspace to have a
higher Signal to Clutter Ratios (SCR). Since the Born approximation is
not used, multiple scattering is considered. In addition, white Gaussian
noise is added to measurement simulations. A 3-GHz modulated Gaussian
pulse with a 1-GHz bandwidth is employed for illuminating the medium.
Finite-Element Time-Domain method (FETD) is used in the measurement
simulations, and the analytic Green’s function of the background is
utilized for backpropagation. Several simulations are provided that show
the effectiveness of this approach.