We propose a “near-field phase center” estimation technique based on planar acquisition setup. It requires a single antenna and an electrically small object to serve as target. The technique allows to estimate the phase center spatial coordinates, as well as its angular dispersion. This data is useful in microwave imaging applications where the antenna operate in near-field regime, such as medical applications (e.g. breast and head imaging). We demonstrate that for a commonly used Vivaldi antenna operating in the 2-5 GHz band, the angular dispersion of the pseudo phase center can be as high as 50 mm. Moreover, we show that incorporating this data in the signal processing algorithms improves the imaging results, by applying it to microwave breast imaging. We believe this type of antennacharacterization techniques will leverage the use of more informative imaging algorithms (e.g. truncated singular value decomposition), since they increase the accuracy of the distance calculations, thus improving the signal to noise ratio.

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Angular dispersion,Antenna measurement,Balanced Antipodal Vivaldi Antenna (BAVA),Microwave imaging (MWI),Near-field measurement,Phase center