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The ground rods create a ground plane under the antenna which increases the gain. The ground rods may extend horizontally from the base, but in antennas fed by coaxial cable as shown here they are usually sloped downward to increase the radiation resistance of the antenna from the 36 ohms of a quarter wave monopole closer to 50 ohms, so the ...
Curtain arrays were originally developed during the 1920s and 1930s when there was a lot of experimentation with long distance shortwave broadcasting. The underlying concept was to achieve improvements in gain and/or directionality over the simple dipole antenna, possibly by folding one or more dipoles into a smaller physical space, or to arrange multiple dipoles such that their radiation ...
Due to its image (b) in the ground plane, a monopole antenna (a) has the same radiation pattern over perfect ground as a dipole antenna (c) in free space with twice the voltage In telecommunications and antenna design, an image antenna is an electrical mirror-image of an antenna element formed by the radio waves reflecting from a conductive ...
Inevitably some antennas won't conveniently fit into any one basic type, so the last section on real antennas is an "everything else" category for a few peculiar antennas that don't fit cleanly into any of the categories or subcategories used in this article; for example, random wire antennas and antennas that are laid down on the ground ...
Openclipart, also called Open Clip Art Library, is an online media repository of free-content vector clip art.The project hosts over 160,000 free graphics and has billed itself as "the largest community of artists making the best free original clipart for you to use for absolutely any reason".
Yagi_uda_antenna.jpg (299 × 500 pixels, file size: 108 KB, MIME type: image/jpeg) This is a file from the Wikimedia Commons . Information from its description page there is shown below.
An antenna rotator (or antenna rotor) is a device used to change the orientation, within the horizontal plane, of a directional antenna. Most antenna rotators have two parts, the rotator unit and the controller. The controller is normally placed near the equipment which the antenna is connected to, while the rotator is mounted on the antenna ...
The antenna rod and its image together act like a dipole antenna of twice the length, so a monopole over an infinite, perfectly conducting plane has a radiation pattern identical to the top half of the pattern of a vertical dipole of twice the length. [1] [70] [71] For the quarter wave monopole, the antenna acts like a half wave dipole.