An effective usage of vector network analyzer for microwave imaging

In this paper, an effective usage of a vector network analyzer (VNA) for microwave imaging of conducting objects is presented. In the measurement arrangement, a novel four-port transmission test set is developed to combine with a laboratory VNA as a four-port transmission VNA. It is shown to effectively acquire four sets of the frequency-swept object scattered field in a multistatic arrangement for each object rotation angle. The image reconstruction formulations of this arrangement are derived under physical optics approximation. The measurement system, calibration method, and experimental results are presented. Reconstructed images of continuous and discrete conducting objects and a B-52 model aircraft measured in the frequency range 7.5-12.5 GHz are shown in good agreement with the scattering object geometries. These measured results demonstrate the effectiveness of the developed four-port microwave imaging system.