A choke ring antenna is a
directional antenna
A directional antenna or beam antenna is an antenna that radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in a certain directio ...
designed for reception of
GNSS
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are op ...
signals from satellites. It consists of a number of
concentric
In geometry, two or more objects are said to be ''concentric'' when they share the same center. Any pair of (possibly unalike) objects with well-defined centers can be concentric, including circles, spheres, regular polygons, regular polyh ...
conductive cylinders around a central antenna.
The first choke ring antennas were invented at JPL; since 1989 they have been improved and extended by many companies.
Due to its intricate construction, it is often enclosed in a protective cover or
radome
A radome (a portmanteau of "radar" and "dome") is a structural, weatherproof enclosure that protects a radar antenna (radio), antenna. The radome is constructed of material transparent to radio waves. Radomes protect the antenna from weathe ...
when placed outside and exposed to the elements.
Benefits
Choke ring antennas have excellent phase center stability, polarization purity, suppression of radiation below the horizon and
multipath rejection. This makes them highly suited for
satellite navigation
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are ope ...
. In a
GNSS
A satellite navigation or satnav system is a system that uses satellites to provide autonomous geopositioning. A satellite navigation system with global coverage is termed global navigation satellite system (GNSS). , four global systems are op ...
ground-based receiver, a choke ring antenna can provide millimeter precision measurements for use in
surveying
Surveying or land surveying is the technique, profession, art, and science of determining the land, terrestrial Plane (mathematics), two-dimensional or Three-dimensional space#In Euclidean geometry, three-dimensional positions of Point (geom ...
and geological measurements.
See also
*
Trimble Inc. - one manufacturer of this product.
*
Patch antenna - a DIRECTIONAL type of antenna.
*
Magellan Navigation
Magellan Navigation, Inc. is an American producer of consumer and professional grade global positioning system receivers, named after Ferdinand Magellan, the first explorer to circumnavigate the globe. Headquartered in San Dimas, California, wit ...
- another manufacturer of this product.
Notes
Radio frequency antenna types
Antennas (radio)
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