Multi-frequency probing signal application for microwave imaging

Experimental results of a multi-frequency probing signal application for microwave imaging radial resolution improvement are presented. Azimuth resolution of radio-holographic microwave imaging systems is determined by probing signal frequency, aperture dimensions and the signal synthesis method. Radial resolution is much lower than azimuth resolution. If the investigated objects are situated in the Fresnel region, it is practically impossible to obtain separate images of objects which are at different distances from the aperture. To improve radial resolution, wideband probing signals can be used. The paper presents a description of the radio-holographic microwave imaging system. Experimental results show that the multi-frequency probing signal application allows the radial resolution of microwave imaging systems to be improved. Three-dimensional microwave image construction based on reconstructed slices becomes possible. Moreover, the use of wideband probing signals improves image quality because of the noise level decrease.