A narrow beam antenna system using an air column having a central conductor and surrounded by an anisotropic plasma column
The radiation pattern of a magnetic ring source of electromagnetic waves in an air column having a central conductor along its axis and surrounded by an annular axially magnetized plasma column is studied. This configuration gives rise to a radiation peak or peaks near, before, or beyond the critical angle depending upon the value of the magnetic field. The direction of the radiation peak depends upon the inner and outer diameters of the annular plasma column, the diameter of the central conductor, the plasma density, and the magnetic field. The direction of the radiation peak is independent of the diameter of the ring source. For very high magnetic fields the peak shifts toward the end fire direction. Based upon these results it is proposed to develop an electronically scannable narrow beam plasma antenna system.