Design of Modulated End-Fire Antennas

The design presented in this article is dedicated to end-fire antennas with a modulated surface-wave structure fed by a dipole or crossed dipole. For short, these are herein called modulated end-fire antennas. The studies were carried out with a modulated corrugated-rod (disks attached to a metal rod) surface-wave structure. The results obtained may be applied to other types of surface-wave structures, such as dielectric on a metal rod or dipole. The length of the investigated antennas ranged between 1.5lambda and 4.5lambda . The increase in directivity obtained was between 5 dB and 3.5 dB, compared to ordinary non-modulated end-fire antennas with the same lengths.