Improving the Imaging Performance of Microwave Imaging Systems by Exploiting Virtual Antennas

Starting from the observation that the correlation coefficient defined by the scattered field data tested by two adjacent antennas decreases with noise, it turns out that the imaging performance can be improved by adding nonredundant scattered field information through more measuring antennas. However, adding more measuring antennas faces practical challenges such as the limited antenna space, high experimental expenses, and a prolonged data collection time. Therefore, the frequency-domain zero-padding (FDZP) interpolation method is proposed to acquire scattered field data on more virtual antennas. To process the data, a linear inversion algorithm based on the modified Born approximation (MBA) and the nonlinear subspace-based optimization method (SOM) are used to image scatterers of moderate and high contrasts, respectively. The effectiveness and the reliability of the proposed approach are then assessed against synthetic data, semi-experimental data from a full-wave simulation software, and experimental data.