Advantages and restrictions of holographic subsurface radars

Holographic subsurface radars (HSR) are not in common usage now; possibly because of the historical view amongst radar practitioners that high attenuation of electromagnetic waves in most media of interest will not allow sufficient depth of penetration. It is true that the fundamental physics of HSR prevent the possibility to change receiver amplification with time (i.e. depth) to adapt to lossy media (as is possible with impulse subsurface radar or ISR). However, use of HSR for surveying of shallow subsurface objects, defects, or inhomogeneities is an increasingly proven area of application. In this case HSR can record images with higher resolution than is possible for ISR images. This paper presents experiments with HSR imaging in media with different degrees of attenuation, and illustrates the principle of HSR through an optical analogy.