Antenna Designer´s Notebook-asymmetric vertical dipole antennas for MF AM transmitting

An asymmetric vertical dipole is proposed as a surface wave transmitting antenna for low-, medium-, and high-frequency applications, where a strong vertically polarized wave is needed. This kind of vertical dipole antenna uses the supporting guys as part of the radiating structure, permitting a very high radiation efficiency, without the classical buried-wire artificial ground plane. It is basically intended for MF AM transmitting antennas, where high radiation efficiency is obtained, but with a simpler and more economical structure. Near-field and power-density analyses show that this antenna results in decreased power density close to the ground, so that power dissipation in the soil below it is avoided