A Modified Plasma Antenna System

Abstract

Ionospheric radio communications as well as satellite-to-satellite communication have been problems for both scientists and engineers because they require the prior knowledge of the natural plasma in the ionosphere. The information carried by a modulated electromagnetic wave may be absorbed or even completely destroyed (black-out), when the wave travels through a plasma medium. Radiation leaving an antenna on earth need not travel very far before it encounters the natural plasma in ionosphere. Also, there are different zones of plasma in the space trapped in the earth's magnetic field in addition to man-made plasma, namely, the shockwave induced plasma that surrounds the body of a space vehicle during high speed-entry of the earth's atmosphere. To overcome the problem of the black-out, we have proposed an antenna system which contains the cylindrical semiconductor plasma surrounded by gaseous plasma and excited by a ring source of electric current. The direction of the radiation peak from the proposed geometry is scannable by the plasma density and the presence of the semiconductor plasma removes the black-out problem. The effect of the other plasma parameters on the radiation pattern is also given.