Jennifer W. Graham

REFLECTION AND TRANSMISSION FROM BIAXIALLY ANISOTROPIC | ISOTROPIC INTERFACES

In this paper we explore electromagnetic behavior of arbitrarily oriented biaxially anisotropic media; speciflcally with respect to re∞ection and transmission. The re∞ection and transmission of electromagnetic waves incident upon half-space and two-layer interfaces are investigated. The waves may be incident from either the isotropic region or the biaxial region. The biaxial medium considered may be aligned with a principal coordinate system or may be arbitrarily oriented. Critical angle and Brewster angle efiects are also analyzed.

Analysis of rectangular waveguide containing uniaxial medium with aligned optic axis

A rectangular waveguide filled with uniaxial medium is treated. Different orientations of the optic axis are considered. Results of wave decompositions with respect to the optic axis are presented and compared with conventional transverse-to-z solutions. Computations show that the effect of anisotropy not only changes the field distributions, but also leads to changes of dominant modes in the waveguide.

Microstrip dipoles printed on biaxial substrates

Microstrip dipole antennas are modeled using arbitrarily oriented biaxially anisotropic substrates. The Method of Moments is used to compute induced currents and the results are used to calculate input impedance, resonant length and directive gain. We show that the orientation of the medium does affect performance metrics but at varying degrees based on the strength of the biaxial anisotropy of the medium.

Rectangular waveguide containing uniaxial medium with tilted optic axis in sidewall plane

Solutions of a metallic rectangular waveguide filled with uniaxial medium are obtained with a new approach. The direction of the optic axis is tilted but lying in one of the sidewall planes of the waveguide. The formulation is based on decomposition into ordinary and extraordinary waves. The proposed method seeks wavenumbers of supported travelling modes, and is also able to calculate both cutoff frequencies and field magnitudes of every mode supported.

Rectangular patch antennas on biaxial substrates

Rectangular patch antennas are modeled using arbitrarily oriented biaxially anisotropic substrates. The Method of Moments is used to compute induced currents and the results are used to calculate input impedance, resonant length, impedance bandwidth and radiation patterns. We show that the biaxial anisotropy and orientation of the medium affect performance metrics.

Reflection and transmission at isotropic-biaxial interface

The problem of wave reflection and transmission at the interface between an isotropic (air) medium and biaxially anisotropic medium is solved and analyzed. We observe behavior that differs from the typical behavior at an isotropic-isotropic interface. It is seen that rotating the permittivity tensor of the biaxial medium with respect to the reference coordinate system significantly affects the reflection and transmission behavior.

Field distributions of the hybrid modes in rectangular waveguides filled with uniaxial media with tilted optic axis lying in sidewall planes

The field distributions of various modes in rectangular waveguides filled with uniaxial media are presented. The presented cases include aligned cases when the optic axis is parallel to one of the coordinate axes and the tilted cases when the optic axis is not parallel to any of the coordinate axes but still lies within one of the two side-wall planes. In the aligned uniaxial-z case the analytical solution is compared with the results of the dyadic greens functions (DGF). In other aligned cases the field distributions of selected extra-ordinary wave modes are also plotted and to be compared with the isotropic case. In the tilted cases, the field distributions of the hybrid modes which are coupled ordinary-waves and extra-ordinary waves show asymmetry which is not seen in the aligned cases and isotropic case. The validity of the hybrid mode field plots are verified by comparing a limiting tilted case with analytical solutions of an aligned case.

Applications of biaxially anisotropic media in review

This paper provides a review of the work to date in the area of applications of biaxially anisotropic materials in RF devices.