Canonical Sources and Duality in Chiral Media

Chiral media are characterized by the constitutive relations D = εE + iXicB and H = B/μ + iXicE where Xic is the chirality admittance introduced to take into account macroscopic handedness or optical activity inherent in the media. In addition we define a chirality impedance and a dimensionless chirality factor to describe the wave properties of this medium. As known for some time, this medium supports the plane-wave propagation of circularly polarized waves of opposing handedness and differing wavenumbers. Here we examine the radiation of electromagnetic waves from a set of simple canonical arrays. This leads us to the notion of duality for chiral media which can be exhibited in a surprisingly simple form. We show that in the far field, both point and extended sources, whether electric or magnetic, radiate two electromagnetic eigenmodes which are of opposing handedness. We also demonstrate sources which access only one of the eigenmodes of the medium. Several applications of the results and array performance in chiral media are noted. Comments Copyright 1988. Reprinted from IEEE Transactions on Antennas and Propagation, Volume 36, Issue 7, July 1988, pages 1007-1013. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Pennsylvania's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/ese_papers/177 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 36, NO. 7, JULY 1988 1007 Canonical Sources and Duality in Chiral Media Absrracr-Chiral media are characterized by the constitutive relations D = €E + it, B and H = B/p + &E where lc i s the chirality admittance introduced to take into account macroscopic handedness or optical activity inherent in the media. In addition we define a chirality impedance and a dimensionless chiralityfactor to describe the wave properties of this medium. As known for some time, this medium supports the plane-wave propagation of circularly polarized waves of opposing handedness and differing wavenumbers. Here we examine the radiation of electromagnetic waves from a set of simple canonical arrays. This leads us to the notion of duality for chiral media which can be exhibited in a surprisingly simple form. We show that in the far field, both point and extended sources, w hether electric or magnetic, radiate two electromagnetic eigenmodes which are of opposing handedness. We also demonstrate sources which access only one of the eigenmodes of the medium. Several applications of the results and array performance in chiral media are noted.