Near-field and three-dimensional aperture synthesis imaging

This paper investigates by simulation some of the capabilities of near-field and three-dimensional imaging which are made possible by accessing phase and amplitude of electric fields from radiometric emission using aperture synthesis systems. The aperture synthesis technique is the main stay of high resolution radio astronomy and is investigated here for the near-field application of personnel security screening in the millimetre wave band. The limitations of the standard radio astronomy visibility-function technique and a matrix method for image generation are investigated for this purpose. It is concluded that several hundred receivers are required for high pixel count (> few thousand) and good quality images and that a new and more efficient algorithms is required to process such numbers of channels from non-planar imaging arrays in the near-field. Investigating the resolution limits of three-dimensional imaging in the near-field region with this technique indicates sub-wavelength resolution may be possible