Investigation of bandwidth effects on UWB near-field imaging

This paper investigates the properties of ultra wideband focusing in the near-field and far-field. The decisive influence of the system´s fractional bandwidth instead of previously claimed array sparsity on the imaging performance of a UWB array is theoretically proved and numerically demonstrated. Our theory shows that the fractional bandwidth of an imaging system must exceed 100% in order to benefit from the merit of the unique UWB array properties and regulate grating lobes thus allowing high resolution imaging with significantly fewer number of array elements.