Enhancing the Directivity of Antennas Using Plasma Rings

A method for improving the radiation directivity of a dipole antenna is introduced based on placing plasma rings in the close proximity of the antenna. The method is applicable to different types of antennas; however, in this work, extensive investigation is focused on its applicability to dipole antennas. Simulation results show that the plasma rings lead to an appreciable enhancement in the gain of a resonant dipole antenna. The dependency of the enhancement in the gain on the plasma parameters has been analyzed. It is also found that the proposed method does not affect the characteristic impedance of the antenna and, therefore, its impedance matching characteristics. The method is experimentally validated using an inexpensive commercial fluorescent lamp. The proposed method can be used for other types of antennas and for antenna arrays.