An antenna system using a plasma column having a central conductor and excited by a waveguide

Abstract

The radiation pattern of an open‐ended circular cylindrical waveguide (excited in the circular symmetric TE01 or TM01 modes) in a plasma column having a central conductor is studied. The field distribution at the open‐end cross section of the waveguide is assumed to be equivalent to the vector sum of current rings of various radii ranging from the outer radius of the central conductor to the inner radius of the circular waveguide at the open end. The radiation pattern is obtained as a vector sum of field components due to individual rings of current. This type of configuration gives rise to an enhanced radiation peak near and before the critical angle. The amplitude and sharpness of the radiation peak depends upon the dimensions of the plasma column, central conductor and the waveguide. The direction of the radiation peak can be changed by changing the plasma density. These results suggest development of an electronically scannable plasma antenna system.