A new class of artificial dielectrics

In the construction of large-size microwave lenses, such as Luneberg lens, a lightweight, isotropic artificial dielectric with controllable refractive index is very much in need. A new class of artificial dielectrics is proposed in this paper which is believed to be well suited for such applications. The proposed dielectrics are not only light-weight, isotropic, and of controllable refractive index but are also believed to be favorable in comparison with other known types of artificial dielectric with regard to homogeneity, bandwidth, loss and cost. The basic innovation for this new class of artificial dielectrics is the random arrangement of a large number of artificially-made lightweight elements. These elements can be made in the form of two concentric spherical shells; the outer shell is made of a dielectric material and the inner shell is made essentially of a conducting material. Several modified forms are also discussed.