Mobile antenna with adjustable radiating element

摘要

A mobile antenna includes a radiating element which can be adjusted to an effective length to tune the antenna to a desired operating frequency without changing the physical length of the element. The radiating element is slidably received in a sleeve member positioned within a central bore having a tapered end of progressively decreasing diameter within the antenna base. The radiating element is locked in position by a deformable rim portion of increased diameter on the sleeve which is drawn into the tapered end of the bore and clamped around the radiating element by means of an axially-aligned bolt threaded into the opposite end of the sleeve. The bolt is preferably accessible only when the antenna is removed from its mounting base to discourage tampering with the antenna.