New fields expressions of a traveling wave circular loop antenna

A technique that is based on spherical wave functions expansion for the free space Green´s function is used to derive exact near and far electromagnetic fields expressions for traveling wave circular loop antennas (TW-CLAs) with arbitrary phase change. These expressions describe separately electromagnetic fields inside and outside a sphere that generated when the loop revolves about its diameter. This makes the investigation of fields in the near region and inside the loop antenna simpler. Furthermore, a simplified expressions for the magnetic fields along the axis of the antenna and the known far-fields expressions for TW-CLA are obtained as special cases of the general field expressions presented in this paper.