Abstract:
Radiation from a slot antenna in an anisotropic plasma with the static
magnetic field in arbitrary direction has been investigated. The field distributions
at the slot aperture have been derived assuming transverse electric
excitation at the feed point and are found to support plane waves of both ordinary
and extraordinary modes. Using the aperture fields as equivalent
electric and magnetic current sheets the. fields outside the slot are derived
in triple Fourier integral forms which are evaluated by residue theorem and
saddle point method to obtain the radiation field. Numerical calculations of
the time averaged Poynting vector were carried out for a half wavelength slot
antenna and for plasma parameters corresponding to the region (a) of Clemmow-
Mullali-Allis (CMA) diagram .. The radial component of the power flow vector
normalized by the maximum power density for a half-wave slot in free-space is
plotted to obtain the directional pattern. Plots of the directional pattern
show that two strong pencil beams are radiated - one along the ground plane in
a direction perpendicular to the slot axis and the other perpendicular to the
plane of the slot. The radiation is dominated by the ordinary-mode power with
a comparatively negligible extraodinary-mode power. With the static magnetic
field in the yz-plane of an xyz-system, the inclination of the static magnetic
field does not significantly influence the radiation pattern of an x-directed
slot but has considerable effect for y and z-directed slots.In the latter
cases. the beam maxima are also slightly tilted from the z and y-axes due to
the lack of propagation symmetry in the yz-plane.
