Subsurface imaging radar

A SAR system (600) for providing SAR images having removed surface clutter to improve detection of subsurface targets, said system comprising:

• a first transmitter (615), a first antenna (605), a first duplexer (610), and a first receiver (620), the first transmitter, antenna, duplexer and receiver collectively being configured for obtaining a horizontally polarised SAR image;
• a second transmitter (635), a second antenna (625), a second duplexer (630), and a second receiver (640), the second transmitter, antenna, duplexer and receiver collectively being configured for obtaining a vertically polarized radar image;
• an incidence angle unit (650) for providing incidence angle data;
• analytical coefficient calculator (655), which is configured to receive said incidence angle data and to calculate coefficients:
• CH,g , CV,g , CH,t , CV, t to be used in the calculations of a linear combiner (665);
• a linear combiner control unit (660) for controlling the linear combiner (665) to linearly combine the images from the first receiver (620) and the second receiver (640) to form a ground clutter suppressed SAR image (ΔF(x,y)) by forming the difference between the horizontal polarization SAR image and the product of the vertical polarization SAR image and one of γmin and CH,g / CV,g, as selected by an operator and conveyed by the linear combiner control unit (660);
• a gamma-min (γmin) finder unit (670), for finding and providing to the linear combiner a γmin of an energy function;
• and
• a selection unit (675) for selecting a homogenous test area T as input to the gamma-min finding unit (670).