Multibaseline interferometric SAR at millimeterwaves

Interferometric Synthetic Aperture Radar has the capability to providethe user with the 3-D-Information of land surfaces. To gather data with high height estimation accuracy it is necessary to use awide interferometric baseline or a high radar frequency. Howeverthe problem of resolving the phase ambiguity at smaller wavelengthsis more critical than at longer wavelengths, as the unambiguous height interval is inversely proportional to the radar wavelength.To solve this shortcoming a multiple baseline approach can be usedwith a number of neighbouring horns and an increasing baselength goingfrom narrow to wide. The narrowest, corresponding to adjacent horns, is then assumed to be unambiguous in phase. This initialinterferogram is used as a starting point for the algorithm, which in the next step unwraps the interferogram with the next widerbaseline using the coarse height information to solve the phase ambiguities. This process is repeated consecutively until the interferogramwith highest precision is unwrapped. On the expense of this multi-channel-approach the algorithm is simple and robust, andeven the amount of processing time is reduced considerably, compared to traditional methods. The multiple baseline approach isespecially adequate for millimeterwave radars as antenna horns with relatively small aperture can be used while a sufficient 3-dBbeamwidth is maintained. The paper describes the multiple baseline algorithm and shows theresults of tests on a synthetic area. The test objects are representative in size for generic buildings. Possibilities and limitationsof this approach are discussed. The relevance for applications of millimeterwave InSAR as means for the extraction ofcharacteristics of buildings is highlighted. Examples of digitalelevation maps derived from measured data are shown.     «

Interferometric Synthetic Aperture Radar has the capability to providethe user with the 3-D-Information of land surfaces. To gather data with high height estimation accuracy it is necessary to use awide interferometric baseline or a high radar frequency. Howeverthe problem of resolving the phase ambiguity at smaller wavelengthsis more critical than at longer wavelengths, as the unambiguous height interval is inversely proportional to the radar wavelength.To solve this shortcoming a multiple base...     »