Analysis of hula-hoop antenna and consideration of its radiation resistance

The current distribution of the 'hula-hoop' antenna is studied and its radiation resistance is considered. It is analyzed by being decomposed into an unbalanced-driven type and a balanced-driven type, on the assumption that the ground is a perfect conductor. Since the balanced type already has been analyzed, this paper is devoted to the unbalanced type, which is called a ring antenna. We present calculated and measured current distributions, and show that the calculated values of the radiation resistance are near 21(2kc)(2kc), where kc equals the electrical length of the distance between the antenna and ground, which agree with those calculated by the Poynting vector method.