Simulation Study of an Impulse Radiation Antenna Array

Abstract

A picosecond-pulse electric field, matching ultra-wideband antenna, can be applied to biomedical noninvasive therapy. Its effect depends largely on the electric field intensity on the target. Because the amplitude enhancement of a picosecond-pulse source is restricted by many factors, ultra-wideband time-domain antenna research has become important. Here, the intensity of the electromagnetic radiation propagated by the antenna was greatly improved by arraying the antenna feed structure. For targeted focusing, an ellipsoidal reflective surface is commonly utilized, but this structure limits the formation feasibility of the feed structure. Here, the feed structure and the reflector were arrayed at the same time, while satisfying the time and spatial consistency of the electromagnetic waves at the target, the intensity of the electric field at the target was greatly improved, and the size of the focal spot was reduced simultaneously. A Gaussian pulse with a 1-V amplitude and a 200-ps width was used as the excitation source. Using this antenna array, a focal spot less than $1\times 1\times 1$ cm was formed at the target. Also, with the increased number of elements in the antenna array, the electric field intensity of the target increased. The relationship between the field intensity at the target and the number of combined antennas is discussed. The increased field strength eventually levels off, which is also consistent with the theory.