Helical antenna
also commonly called helix antennas. A helical antenna is an antenna consisting of a conducting wire wound in the form of a helix. In most cases, helical antennas are mounted over a ground plane. The feed line is connected between the bottom of the helix and the ground plane. Helical antennas can operate in one of two principal modes: 1) Normal Mode: the dimensions of the helix are small compared with the wavelength. The radiation is linearly polarised parallel to the helix axis. 2) Axial Mode: the dimensions of the helix are comparable to a wavelength. It radiates circularly polarised radio waves. |