Metamaterials with negative refractive index, also called left-handed materials, have two unusual but related properties when compared to regular right-handed media (Veselago, 1968 [1]):

• The phase velocity of electromagnetic waves is anti-parallel to the group velocity and the flow of energy,
• Waves are refracted at a negative angle by such materials.

MEFiSTo Electromagnetic Simulators empower users to explore these properties, to visualize the field behavior, and to virtually prototype components and devices made of such materials.