Coaxial antenna
Encyclopedia
A coaxial antenna is a particular form of a half-wave dipole antenna
, most often employed as a vertically polarized omnidirectional antenna
.
Bonnie Crystal was granted the US patent 7,151,497 Coaxial Antenna System on December 19, 2006 after filing in 2003 for new types of coaxial antennas with reduced size providing efficient broadband, wideband and controlled bandwidths, using radiation by the outside of the coaxial elements.
The outer (sheath) conductor is connected to a quarter-wavelength conducting sleeve into which the cable is inserted, and the inner conductor protrudes vertically above the sleeve for a quarter-wavelength. Also, additional quarter-wavelength sections may be connected to outer conductor to form a better ground plane.
Dipole antenna
A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other , with a small space between them. The radio frequency voltage is applied to the antenna at...
, most often employed as a vertically polarized omnidirectional antenna
Omnidirectional antenna
In radio communication, an omnidirectional antenna is an antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This radiation pattern is often...
.
History
Arnold B. Bailey was granted the US patent 2,184,729 Antenna System on December 26, 1939 after filing in 1937 for a vertical antenna providing coaxial element sleeve structures.Bonnie Crystal was granted the US patent 7,151,497 Coaxial Antenna System on December 19, 2006 after filing in 2003 for new types of coaxial antennas with reduced size providing efficient broadband, wideband and controlled bandwidths, using radiation by the outside of the coaxial elements.
Configuration
In the most basic form, a quarter-wavelength section of coaxial cable is prepared such that the inner and outer conductors are separate but still attached to the remaining cable.The outer (sheath) conductor is connected to a quarter-wavelength conducting sleeve into which the cable is inserted, and the inner conductor protrudes vertically above the sleeve for a quarter-wavelength. Also, additional quarter-wavelength sections may be connected to outer conductor to form a better ground plane.