Accession Number : ADP005707

Title :   The Current and Field Distribution of a High Power Satellite Antenna Affected by Nonlinear Plasma Sheath Phenomena,

Corporate Author : DEUTSCHE FORSCHUNGS- UND VERSUCHSANSTALT FUER LUFT- UND RAUMFAHRT E V OBERPFAF FENHOFEN (GERMANY F R)

Personal Author(s) : Bethke, K. -H. ; Edenhofer, P.

Report Date : MAY 1987

Pagination or Media Count : 10

Abstract : For electromagnetic adn acoustic radiation from antennas in a plasma environment the fundamental electro- and hydrodynamic equations are presented involving nonlinear source terms up to the third order. A perturbation procedure is applied to derive a numerical solution from a set of coupled integral equations for the linearized (first-order) magnetic field and electron density describing the dipole radiation into a homogeneous compressible plasma. The solution is given in terms of an equivalent surface current density based on a Green's function representation. An electron absorption coefficient is introduced to account for plasma-antenna surface interactions. Due to nonlinear ponderomotive forces an inhomogeneous plasma sheath is shown to build up around the dipole, where the antenna-to-plasma coupling turns out to be strongest in the near-field (feeding zone) of a high power transmitting antenna. The linearized field and density are taken along with the nonlinear source terms to determine the higher-order fields for antenna characteristics such as the input impedance. Numerical results are discussed for an electrically short dipole embedded in an ionospheric plasma.

Descriptors :   *SPACECRAFT ANTENNAS, *PLASMA SHEATHS, DIPOLES, IONOSPHERE, ELECTRIC FIELDS, NEAR FIELD, NONLINEAR ANALYSIS, INTEGRAL EQUATIONS, MAGNETIC FIELDS, ELECTRON DENSITY, ABSORPTION COEFFICIENTS, ELECTRONS, COUPLING(INTERACTION), WEST GERMANY.

Subject Categories : Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE