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 ... [Show full abstract] two-dimensional Helmholtz
equation, it is numerically shown that three active exterior devices
placed around the object suffice to produce very good cloaking.