Source ambiguities for imaging and interferometric SAR

One of the greatest costs of any spaceborne mission is the total instrument mass. For SAR, one third of the mass is typically related to the antenna structure, whose elevation and azimuth dimensions are used to increase the signal to noise ratio as well as to reduce the presence of spurious signals. As the wavelength increases, so too does the antenna dimensions to achieve equivalent performance. Thus, the antenna for a P-band mission is likely to be several times larger than that for, say, an L-band, mission. The L-band antennas for SIR-C and JERS-1 for example are on the order of 12m in azimuth and 3/2.5 meters in elevation. An equivalent P-band antenna would be more than three times larger (but, as will be shown, not necessarily in the azimuth dimension). Understanding the tradeoffs between signal to noise ratio, ambiguous sources and the antenna dimensions is a key to producing a cost effective low frequency mission design. In this short paper, the authors focus on the presence of source ambiguities, or those spurious signals arising from ground targets which are imaged concurrently with the intended target