20-03-2012, 12:32 PM
Plasma Antennas: Survey of Techniques and the Current State of the Art
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ABSTRACT
Plasma antennas refer to a wide variety of antenna concepts that incorporate some use of an ionized medium. This
study summarizes the basic theory behind the operation of plasma antennas based on a survey of patents and
technical publications. Methods of exciting and confining plasmas are discussed, and the current state of the art in
plasma technology is examined.
Introduction
The term plasma antenna has been applied to a wide variety of antenna concepts that incorporate
some use of an ionized medium. In the vast majority of approaches, the plasma, or ionized
volume, simply replaces a solid conductor. A highly ionized plasma is essentially a good
conductor, and therefore plasma filaments can serve as transmission line elements for guiding
waves, or antenna surfaces for radiation. The concept is not new.
Fundamental Plasma Theory
A plasma can be generated from neutral molecules that are separated into negative electrons and
positive ions by an ionization process (e.g., laser heating or spark discharge). The positive ions
and neutral particles are much heavier than the electrons, and therefore the electrons can be
considered as moving through a continuous stationary fluid of ions and neutrals with some
viscous friction. Furthermore, the propagation characteristics of electromagnetic (EM) waves in
a uniform ionized medium can be inferred from the equation of motion of a single “typical”
electron. Such a medium is called a “cold plasma.”