A synthetic aperture radar (SAR) compensates for ionospheric distortions based
upon measurement of the group delay, particularly when operating in the VHF/UHF
band. The SAR is based upon a multi-input multi-output (MIMO) technique for estimating
the effective ionospheric conditions, which is referred to as the group delay approach.
The group delay approach is divided into a 1-dimensional (range) approach and a
2-dimensional (range and cross-range) approach. The group delay measures the effective
or observed TEC, which is used to reduce the ionospheric distortion.
