Multipole effects in a toroidal tunable planar metamaterial

A tunable planar metamaterial with a high contribution of the toroidal dipole moment in the microwave range is theoretically and experimentally studied. The properties of such a structure are controlled by switching on a PiN diode. It is demonstrated that the metamaterial can be transparent or reflective, depending on the resistance of the PiN diode. Such a metamaterial is relevant for a wide range of applications, for example, for reducing the radar signature, suppressing scattering, and creating highly sensitive sensors and electromagnetic field sensors.