Microwave holographic subtraction for imaging of buried objects

A simple technique for subtracting microwave holograms is presented. The technique is novel in that it superimposes a hologram over the complement of a second one obtained through an inverting amplifier with unity gain. Since the holograms contain mainly the wavefront information, only the difference of two dissimilar microwave fields is recorded. The technique is demonstrated by subtracting the effect of the front-surface reflections from the hologram of an object concealed behind a box of dry sand to retrieve the image of the object itself. This technique can have many applications, like in imaging of buried objects in dielectrics.