A magnetic field controlled negative-index microwave lens

A three-dimensional lens with magnetic field control of the index of refraction and focal length has been designed and characterized over 2-18 GHz. The lens is made of a lattice without the ferrite cubes, a refractive index n approximate to -1 is measured at 11.25 GHz. With the introduction of ferrite cubes in the lattice, n could be tuned over the range -1.2 to + 1.8 for nominal bias magnetic fields H. The focal point for the lens with n approximate to -1, for example, could be displaced by 2 cm by tuning H from 4100 to 4125 Oe. Theoretical estimates of the lens characteristics are in agreement with the data. (c) 2008 Wiley Periodicals, Inc.