  A new method of cloaking is presented. For two-dimensional quasistatics it is
proven how a single active exterior cloaking device can be used to shield an
object from surrounding fields, yet produce very small scattered fields. The
problem is reduced to finding a polynomial which is approximately one within
one disk and zero within a second disk, and such a polynomial is constructed.
For the two-dimensional Helmholtz equation, it is numerically shown that three
active exterior devices placed around the object suffice to produce very good
cloaking.
