Metasurfaces are used to design mantle cloaks based on scattering cancellation which involves surface impedance analysis. Theory of characteristic modes is a good tool for analyzing the scattering of a metallic object because it is based on the surface impedance and brings physical insight into the scattering properties of a structure independently of an excitation source. The theory of characteristic modes is applied in the analysis of a cylindrical cloaking metasurface used for a UMTS antenna. The result provides physical insight into the design of mantle cloaks. It shows that the direction of the fundamental modal current distribution of the cloak is at 90 • to that of the UMTS antenna.