Abstract: The present invention relates to a parallel-ring type antenna which is reduced in entire physical length, and has a wider bandwidth and a more excellent return loss, while having the same resonant point, by changing a loading portion of a retractable antenna employing a top-loading method that can easily secure the physical length of the antenna. Further, characteristics electrically similar to those of a helical antenna can be achieved by applying the parallel-ring type to the loading portion of the monopole termination. In addition, the entire length of an antenna can be reduced, while accomplishing the same resonance as that of the helical antenna, by employing a change in return loss according to a change in the thickness of the parallel ring, the distance between the rings, the diameter of the ring, and/or the length of the loading portion.