ELECTRO-MAGNETIC RADIATION IN ANISOTROPIC MEDIA. Technical Note No. 6
The conditions which must be satisfied by the elements of the tensor material constants of lossy (and lossless) media are studied. The duality between ferrites and plasmas, which permits the application of results obtained for one of the two media to the other by means of certain substitutions, is discussed. Plane electromagnetic waves in unbounded lossy (and lossless) anisotropic media are investigated. Wave matrices are defined, the zeros of whose determinants determine the propagation constants of the two wave types which are possible for a given direction of propagation. Formulas for the propagation constants and the polarization of waves in a plasma are derived. A general method is presented for solving radiation problems in unbounded, homegeneous, anisotropic media; this method involves dyadic Green's functions and their spatial Fourier transforms. It is shown that the latter can be described in terms of the inverse wave matrices. The elements of these transforms are computed for the case of a plasma. Formulas are derived which give the power radiated by any distribution of alternating electric and/or magnetic currents in terms of the spatial Fourier transforms of the Green's functions and the currents. The amount of power radiated per unit length of a current distribution and that radiated per unit area are discussed. The method is applied to the study of the waves excited by osclllating dipoles arranged in a plane in an anisotropic medium and particularly in a plasma. In another application an expression is obtained for the power transferred from a modulated flat beam of ions to the plasma into which it is being injected. This latter device can be used to heat a thermonuclear plasma. The power radiated by an elementary electric dipole in a lossless plasma is studied in greater detail. The dependence of this power on the dipole's orientation and polarization can be described by means of a Hermitian matrix. Integral representations for the elements of this matrix are obtained. For special cases of anisotropy, including the case of the uniaxial crystal (or a plasma in a "very high" magnetic field), these integrals can be evaluated elementarily. For general cases of anisotropy they have been evaluated numerically for a set of parameters with the aid of an electronic computer. The power radiated by an elementary magnetic dipole is also investigated. (auth)
- Research Organization:
- Oxford Univ. Engineering Lab.
- NSA Number:
- NSA-15-000973
- OSTI ID:
- 4147445
- Report Number(s):
- AFOSR-TN-60-1042
- Country of Publication:
- United States
- Language:
- English
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