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A choke ring antenna is a particular form of omnidirectional antenna for use at high frequencies. It consists of a number of conductive concentric cylinders around a central antenna. Due to its delicate construction, it is often enclosed in a protective cover or radome when placed outside and exposed to the elements.
Choke ring antennas are notable for their ability to reject multipath signals fading from a source. Since the path that a signal takes from a transmitter to receiver can be used to measure the distance between the two, this makes it highly suited for GPS and radar applications. In a GPS ground based receiver, a choke ring antenna can provide millimeter precision measurements for surveying and geological measurement applications.
The choke ring design originated at the Jet Propulsion Laboratory.