Characteristics of two-arm wire conical spiral antennas

Conical Archimedes spiral antennas are designed to produce radiation patterns of cardoid or conical shapes for satellite applications. The method of moments is used to calculate the current distribution on the spiral arms. The radiation pattern, gain, polarization, and input impedance are presented. The standing-wave ratio (VSWR) and the reflection coefficient of the antenna are investigated over a wide frequency band. It is shown that the radiation pattern of this antenna can be easily shaped by setting the geometrical parameters of the conical spiral such as the cone angle and the spiral constant. It is noticed that the conical spiral antenna has a wide bandwidth over which the radiation characteristics and the input impedance are maintained satisfactory.