A GB satisfies Maxwell's equations only in the paraxial region, namely close to the axis of propagation.
Their descriptive capability relaxes but does not remove the restriction to satisfy Maxwell's equations only in the paraxial region; this produces slow convergence in describing far out-of axis lobes.
These equations are completely accurate for a small region, known as the paraxial region
. A well-corrected optical system will follow the first-order expressions almost exactly.
GB  have the limitation of satisfying Maxwell's equations only in the paraxial region
; however, they desirably don't possesses branch singularity in space.
They arise in the ovary but can be located at the midline and in paraxial regions
of the body and unusual locations, including lungs or ilea, were described .
In our method, the radiating far fields on the right-hand-sides of (6) can be fast calculated by truncating CSB directional fields within the paraxial regions
. Once [Z.sub.l] and [F.sub.l+1,c] are assembled, the aggregation matrix for level l