Radio antennas
AssigneeAntenna Products Corp.
InventorHoward Bottomley
Life of this patent
Estimating the term…
Abstract
A radio antenna has an antenna element 12 which is slidable with respect to a casing of the radio between an extended position (FIG. 5) and a retracted position. In the extended position, a metal plate 15 on the lower end of the antenna element 12 cooperates with a fixed dielectric 17 and a fixed metal plate 17 to form a capacitor providing a signal link to a coaxial cable 18 leading to a matching network. This avoids the need for a sliding metal connection, as in the prior art. In the retracted position of the antenna element 12, the capacitive link is effectively disconnected.
Claims7
A radio antenna comprising a main antenna element, a housing with respect to which the main antenna element is slidably movable between an extended position of the element and a retracted position of the element, a first electrically conducting member attached to the housing and forming a stationary capacitor plate for connection to radio transmitting or receiving apparatus, a second electrically conducting member attached to an inner end of the main antenna element and forming a movable capacitor plate, and a further antenna element carried by the housing for connecting to the radio transmitting or receiving apparatus, in the extended position of the main antenna element the stationary and movable capacitor plates forming a capacitor which constitutes an electrical signal link between the main antenna element and the radio transmitting or receiving apparatus, in the retracted position of the main antenna element the movable capacitor plate being spaced from the stationary capacitor plate so as effectively to disconnect the electrical signal link, the further antenna element comprising a receiving/transmitting antenna element when the main antenna element is in the retracted position thereof, the main antenna element being an elongated rod which passes through a central aperture in the stationary capacitor plate, and including a dielectric washer attached to the stationary capacitor plate, the washer being disposed between the movable and stationary capacitor plates in the extended position of the main antenna element.
Dependencies are inferred from the claim text.