Stability of Step-tapered Design Alteration in Radius of Elements on Radiation Characteristics of Yagi-Uda Antennas

The radiation pattern of an optimized Yagi-Uda antenna does not suffer from the minor radius alteration (such as 1/2: 50% reduction or 1/4: 75 % reduction) of elements even if the alteration is uniform for entire elements. The minor step-tapered design alteration in radius of radiating elements greatly affects the radiation characteristics of the Yagi-Uda antenna, which is originally designed with the uniform radius. However, the step-tapered radius element structure of Yagi-Uda antenna shows the stable radiation characteristics in terms of the radius alteration.