Dispersion properties of non-radiating configurations: Finite-Difference   Time-Domain modeling
  A finite-difference time-domain (FDTD) numerical analysis is used to demonstrate that a toroidal solenoid, coaxial with an electric dipole, is a remarkable non-radiating configuration. It can be used to measure the dielectric permittivity of any ambient matter. It becomes a directional radiator at an interface between two dielectric media, depositing energy in the material with the highest polarizability. 
A. D. Boardman, K. Marinov, N. Zheludev, V. A. Fedotov