多层球形手征介质透镜的焦点

应用并矢格林函数方法，给出了点源激励和阻抗匹配时多层球形手征介质透镜（Ｃｈｉｒｏｌｅｎｓ）的远区场分布；应用几何光学近似条件，得到了它的焦点计算公式．以双层和１０层手征介质球镜为例，考虑了手往导纳对焦点位置的影响．

Focal Points of Multilayered Spherical Chirolens

The focal pointS of single chiral sphere was determined by Engheta and Kowarz in 1990,under thecondition that impedance-matching is realizable[1];but,in the authors'opinion,such impedance-matching is very difficult if not impossible to realize.In order to realize the impedance-matching between spherical chirolens and air,aD efTeCtive method is proposed by the authors,in which the chirolens is made ofmultilayered asymptotic spherical structure.ID this paper, the authors, utiliaing scattering superposition method. derive the analytical expressionof multilayercd spherical chirolens. under the excitation of an electric current source.Then, the authorsobtain the field distribution in the far-zone of four-layer spherical chirolens for point-source excitationand impedance-matching. Finally, applying engineering theory of geometrical optics,which has proved tobe highly successful in analystes of problems of ordinary lens antennas,the authors obtain formulas forcomputing focal points of four-layer, three-layer.two-layer and one-layer cbirolenscs respectively.Theauthors' formulas include the corresponding formulas for foupelayer,three-layer.two-layer andone-layer ordinary spherical lens as special cases.