Electromagnetic Characteristics of Yagi-Uda Antenna at HF/VHF/UHF

Abstract

In this paper, the radiation characteristics of Yagi-Uda antenna operating at High Frequency (HF), Very High Frequency (VHF) and Ultra High Frequency (UHF) are examined. Upon employing method of moments, the current distribution on the antenna emerges from the solution of matrix equation. It is found that the angular distribution of electric field intensity generated in free space by the antenna, obtained by evaluating the integral of associated current distribution, is characterized by patterns with significant portion of radiation beam in the main lobe in the direction of Yagi axis. This is accompanied by relatively small undesirable radiation in the minor lobe, and which persist over those communication frequencies. It is observed also that the current distribution that generates the radiated electric field patterns is relatively consistent over the same range of frequency.