Calculation of antenna radiation center using angular momentum

An algorithm to compute the Radiation center of an antenna based on the Spherical wave expansion is introduced. The method is based on the angular momentum vector that is uniquely defined for any antenna far field pattern. The radiation center is defined as the unique point where the magnitude of the angular momentum is minimized with respect to translations of the far field. This corresponds to minimizing the phase variations in the antenna far field pattern. In addition the Current distribution axis can be determined, corresponding to minimization of the vertical component of angular momentum

Transient external 3D excitation of a dispersive and anisotropic slab

Propagation of a transient electromagnetic field in a stratified, dispersive and anisotropic slab, and related direct and inverse problems, are investigated. The field is generated by a transient external three-dimensional (3D) source. The analysis relies on the wave splitting concept and a two-dimensional Fourier transformation in the transverse spatial coordinates. An investigation of the physical properties of the split fields is made. To solve the direct and inverse scattering problems, wave propagators are used. This method is a generalization and a unification of the previously used imbedding and Green functions methods. The wave propagator approach provides an exact solution of the transmission operator. From this solution it is possible to extract the first precursor (the Sommerfeld forerunner). These results also hold for a bi-anisotropic slab. An inverse problem is outlined using reflection and transmission data corresponding to four, two-dimensional Fourier parameters. Due to the stratification of the medium, the inverse Fourier transformation is not needed in the inverse problem

Effect of dissipation on the constitutive relations of bi-anisotropic media - the optical response

This paper discusses the restrictions that dissipation forces on the material parameters and responses of bi-anisotropic media. The treatment is a general time domain analysis where six-vector formalism is applied. Energy conditions set limitations on the optical response dyadics and dyadic susceptibility kernels of the material that have to be satisfied regardless the time dependence of the fields. This paper will treat in detail the resulting restrictions for the optical response of bi-anisotropic media. Examples are given for some special cases. Also uniqueness and equivalence aspects of constitutive relations in the time domain are discussed