An FET-Based Unit Cell for an Active Magnetic Metamaterial
  A particle that can be used to create an active magnetic metamaterial has been designed using an FET transistor loaded in its gate by a conducting ring and in its source by a parallel resonance circuit. The design procedure is discussed and the working principle is experimentally demonstrated in the RF range. 
Lukas Jelinek and Jan Machac
cond-mat.mtrl-sci physics.optics