1. A method for identifying a target of interest, the method comprising: generating, by a radar transmitter and a radar receiver, one or more digitized radar returns; forming, by a processing unit, a processed resonance map from the one or more digitized radar returns, the processed resonance map comprising a plurality of pixels, each pixel having a value; and forming, by the processing unit, a signature discriminant array, each element of the signature discriminant array corresponding to a pixel of the plurality of pixels, each element of the signature discriminant array being: the fourth power of the ratio of: the power within an inner rectangle, to the difference between the power within an outer rectangle and the power within the inner rectangle when the power within the inner rectangle exceeds the power within the outer rectangle, and zero otherwise; the power within the inner rectangle being the sum of the squares of the pixel values in a rectangle of a first height and a first width centered on the corresponding pixel of the plurality of pixels, the power within the outer rectangle being the sum of the squares of the pixel values in a rectangle of a second height and a second width centered on the corresponding pixel of the plurality of pixels, the second height and width being greater than the first height and width, respectively, and the first height and width and the second height and width being selected to match a target of interest.