Helical loaded monopole antenna

As a result of adjustments made in countries neighboring Japan in response to an international conference to reestablish the frequency spectrum usage, frequency divisions were made and medium-frequency divisions for Japan were rearranged. The interference caused by this rearrangement has been considerable. Prompted by the Ministry of Posts, a medium-frequency relay commission was established to study this problem. One suggestion put forth by the commission was the use of helical loaded antennas along with other low-cost small antennas. This paper proposes a solution wherein the field of the received signal is increased. Also, a numerical analysis and experiments to determine the apparent efficiency of these antennas are presented. The theoretical and measured data show good agreement.