Calculation on characteristics of VLF umbrella inverted-cone transmitting antenna

This paper introduces a new kind of VLF umbrella inverted-cone transmitting antenna, which an inverted cone is added to the typical umbrella antenna. Two VLF umbrella antenna systems - umbrella inverted-cone antenna and typical umbrella antenna are modeled and simulated by using electromagnetic simulation software (FEKO). In order to study the electrical characteristics of umbrella antenna, top-hat wires, down-lead wires, ground screen, effective radius of supporting tower and metallic loss are taken into consideration in the model. Electric characteristics, such as input reactance, radiation resistance and effective height are calculated and studied using the antenna models established. The result shows that the effective height and the radiation resistance of umbrella inverted-cone antenna has increased apparently.