Electric characteristics of a dipole near the boundary between two media.

This paper addresses the cases where a dipole is located near the boundary between two lossless media, and determines the equivalent permittivity for a homogeneous medium with matching the frequency characteristics of input admittance by means of the FDTD method. The paper reveals that the equivalent permittivity of the dipole near the boundary of lossless media consists of a complex number, and describes the behavior where the permittivity changes as a function of the gap between the dipole and the boundary. In particular, as the dipole leaves the boundary toward the medium with a lower permittivity, the equivalent permittivity changes discontinuously, indicating the asymmetric nature of the electric characteristics with respect to the boundary interface. Experimentally, the input admittance was measured when a monopole was placed near the boundary between a finite-size clay and air. Experimental results and the results of theoretical analyses are compared to demonstrate the validity of this paper. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 89(9): 60–67, 2006; Published online in Wiley InterScience (<URL>www.interscience.wiley.com</URL>). DOI 10.1002/ecja.10232 [ABSTRACT FROM AUTHOR]