Ultra-wideband radio tomographic imaging with resolution near the diffraction limit

The experimental ultra-wideband radio tomographic imagings inside and behind dielectric barriers with resolution near the diffraction limit are described. The problem is solved by the method of radio wave tomosynthesis using the theory of spatial spectra of the received signals. The ultra-wideband pulse sensing of the air—building structure medium, developed in Tomsk State University, are described. It has been shown that for the case of sensing with ultra-wideband pulses of 0.2 ns duration, the resolution is about 2 cm. The paper also shows the possibility of accelerating scanning of the investigated space through the use of the MIMO (timed or switched) antenna array technology. As in the timed mode the distance between the receiving and transmitting antennas varies from time step to time step, the algorithm of processing the data obtained from the array is to be modified. The modification itself is a nonlinear stretching of the received UWB signal in time. The signal transformation allows preparation of data for the above algorithm to receive three-dimensional images of the tested space. The paper presents the results of the processed experimental data which confirm the efficiency of the proposed method for MIMO arrays. The resulting image resolution is about 2 cm.