It is proved that one can choose a control function on an arbitrarilly small open subset of the boundary of an obstacle so that the total radiation from this obstacle for a fixed direction of the incident plane wave and for a fixed wave number will be as small as one wishes. The obstacle is called "invisible" in this case.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-ap90-2-4, author = {A. G. Ramm}, title = {Invisible obstacles}, journal = {Annales Polonici Mathematici}, volume = {92}, year = {2007}, pages = {145-148}, zbl = {1134.35032}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ap90-2-4} }
A. G. Ramm. Invisible obstacles. Annales Polonici Mathematici, Tome 92 (2007) pp. 145-148. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-ap90-2-4/