Ads
related to: 70 cm ground plane antenna base cb
Search results
Results from the WOW.Com Content Network
For a monopole antenna (a), the Earth acts as a ground plane to reflect radio waves directed downwards, making them seem to come from a virtual "image antenna" (b).In Telecommunications, a ground plane is a flat or nearly flat horizontal conducting surface that serves as part of an antenna, to reflect the radio waves from the other antenna elements.
[17] [8] A common type for mounting on masts or stationary structures is the ground plane antenna, consisting of a quarter-wave whip antenna with a ground plane of 3 or 4 wires or rods a quarter-wavelength long radiating horizontally or diagonally from its base, connected to the ground side of the feedline. [18]
Whips mounted on vehicles use the metal skin of the vehicle as a ground plane. In hand-held devices usually no explicit ground plane is provided, and the ground side of the antenna's feed line is just connected to the ground (common) on the device's circuit board. [2] Therefore, the radio itself serves as a rudimentary ground plane.
A whip antenna with several rods extending horizontally from base of the whip in a star-shaped pattern, similar to an upside-down radiate crown, that form the artificial, elevated ground plane that gives the antenna its name. The ground plane rods attach to the ground wire of the feedline, the other wire feeds the whip. Since the whip is ...
Another mobile antenna is the continuously loaded half-wave version. They do not require a ground plane to present a near-50 ohm load to the radio, and are often used on fiberglass vehicles such as snowmobiles or boats. They are also useful in base stations where circumstances preclude the use of a ground-plane antenna.
The rubber ducky antenna (or rubber duck aerial) is an electrically short monopole antenna, invented by Richard B. Johnson, that functions somewhat like a base-loaded whip antenna. It consists of a springy wire in the shape of a narrow helix , sealed in a rubber or plastic jacket to protect the antenna. [ 1 ]
An amateur radio repeater system consisting of a 70 cm repeater and a 2-meter digipeater and iGate. Coaxial cavity RF filter at 2 meter repeater An amateur radio repeater is an electronic device that receives a weak or low-level amateur radio signal and retransmits it at a higher level or higher power, so that the signal can cover longer ...
One practical concern when comparing the 70-centimeter band to the 2-meter band is that a quarter-wavelength antenna is much less unwieldy at 70 centimeters than it is at 2 meters. Portable antennas for 2 meters are generally continuously loaded coil spring or " rubber duck " types, while on 70 centimeters they can be a full quarter wavelength.
Ads
related to: 70 cm ground plane antenna base cb