The spherical antenna is a classical problem studied by numerous authors,[1]-[11],due to its
simple geometry to allow an exact solution. It is also a practical and useful device for space
communications in that many satellites are spherical in shape and it is often economical to use
the satellites themselves as antennas. To understand the effect of anisotropicity upon the
antenna characteristics, this thesis studies a spherical antenna which conducts only in the
direction of a spiral. While the addition of anisotropic boundary conditions complicates the
mathematics needed to study the antenna, it also gives added degree of freedom in designing the
antenna for desired properties.
In 1964, Mei and Meyer [7] have presented a theoretical foundation for analyzing the spherical
spiral antennas. However, there were still many problems unsolved at that time, due to complex
geometry and complicated coupling among the modes radiated. Some representatives are:(1) the
undetermined leading coefficients of the series for the nonuniformly excited antenna, (2) the
lack of proper formulation for the input admittance of the antenna under nonuniform excitation,
(3) the lack of investigation concerning the coupling of each component mode of a total wave.
consequently, such informations as given below are still not available:(a) tyhe effect of spiral
slope upon the antenna characteristics (polarization and admittance etc.), (b) the Frequency
response of the antenna characteristics, (c) the proper mode coupling to give antenna resonance,
(d) comparison of the merit between the spiral antennas and the conventional conducting sphere.
Thepurposes of this thesis are to present a theory for solving the aforementioned difficulties
and to supply quantitative informations to facilitate the design and optimization of the spherical
spiral antenna.