The helical loaded monopole antenna

Abstract

Medium-wave radio broadcasting in Japan has been disturbed by jamming from neighboring countries. To deal with this problem, consideration should be given to the use of numerous low-power broadcasting stations, each with a rather narrow service area. A helical loaded monopole antenna is recommended for use in such stations. A field experiment was conducted using a model one-tenth the size of the actual antenna. The antenna impedance was almost identical to the theoretical and the apparent efficiency was 32 percent at an antenna height of 0.1 wavelength.