Transmitting-Mode Time Reversal Imaging Using MUSIC Algorithm for Surveillance in Wireless Sensor Network

The electromagnetic time reversal (TR) detection and imaging using multiple signal classification (MUSIC) is extended to the Maxwell equations problems with the transmitting-mode configurations, where the transmitter and receiver arrays are bistatic and the arrays elements are arbitrarily distributed. Based on this type of setup, the multistatic response matrix is derived in detail for target-scattering by relatively small anisotropic spheres located in the imaging domain. Then the electromagnetic transmitting-mode MUSIC algorithm is proposed by defining the pseudo-spectrum deduced from the Maxwell equations. By such extension, following advantages are achieved: a) leading to more accurate location and higher imaging resolution because the noncoincident arrays actually increase the effective aperture of the array; b) making the algorithm more flexible and practical; c) enlarging the coverage area of the detection system due to the reciprocal mapping between the transmitter and receiver spaces; and d) overcoming one special problem that the echo-mode encounters when one target is atop another one in the upright direction of the transceiver antenna array even they are far-separated. Based on these advantages, we have numerically discussed typical applications of the proposed method for surveillance in wireless sensor network. Through examples, the validity, the improvement, and the extended potential of the electromagnetic transmitting-mode time reversal MUSIC method are verified.