INVERSION OF SYNTHETIC APERTUR,E R,ADAR (SAR) - MSpace ...

in lange-azimuth dor.nain (Bennett an rl Curnrning [6]).
The Fourier tlansform
of s(r,l;4) rvith respect to the azirnuth c is given
lry
s(k",t;q) -
-'r, - +5) "",{'i*\ (3 52)
c + LÐõ/ l4ao.
whele li:. is the azirnuth wavenurlber ol spatial angulal Dop¡rler. fiequency.
The detailed delivation for the Eq.(3.52) is sumrnarizecl in Appenclix C. The
exponential terrn exp(-z4n'4/ì), rvhose phase is founcl in Eq.(3.42), is inclepenclent
of fr,, and thus is not so irnpoltant as the k"-clepenclelt last trvo
telms,
The range miglation colrection in the range-Doppler dornain is pelformed
as a tirne shift by
(3.53)
This time shift process requires a lange domain interpolation, rvhich is oftel
clifficult to achieve rvith high accuÌacy. Errors clue to ilter.polation result in
in.rage blurring and the loss of phase infolmation. In aclclitiol, this r.ange
migration corlection folmula is not exact but basecl on a quach'atic approximation
of A(c,4) in Eq.(3.50).
After the i'ange miglatiol correctiorr, the azimuth cornplession of conventional
apploaches irr the range-Doppler clorlain is pelfor.med using a reference
function given by
^^ t2
At(,{") : -l +u6 }
""'{-'iX}
(3.54)
which is a complex conjugat,e of the last expouential ter.rn in Ðq.(3.52). It is of
intelest to compâ.Ìe the conventional azimuth leference function il Eq.(3.54)
6l