High resolution synthetic aperture radar using a multiple sub-band technique

The resolution of spaceborne synthetic aperture radar (SAR) does not compare well with optical sensors (~25 m for the ERS SAR compared with ~5 m for the SPOT panchromatic channel). For many applications the user demands better resolution from the SAR than currently achievable. There is therefore considerable interest in improving the SAR resolution by an order of magnitude, say. There are two basic ways of achieving this aim using (1) strip map SAR, and (2) spotlight SAR. There is another approach based on partitioning the total array length into sub-arrays which offers the potential for higher resolution without the swath limitations of a conventional strip map solution and without the beam steering of a spotlight solution. The paper reviews this technique. It presents a natural generalisation of this technique to one which additionally partitions the total system bandwidth into sub-bands. This concept is outlined, and the implications for processing are discussed. Comments are included on the required isolation between the sub-bands, and the advantages and disadvantages of the new sub-band technique are discussed