File:Antenne gp vhf 1.jpg
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Size of this preview: 387 × 599 pixels. Other resolutions: 155 × 240 pixels | 310 × 480 pixels | 496 × 768 pixels | 1,276 × 1,976 pixels.
Original file (1,276 × 1,976 pixels, file size: 1.26 MB, MIME type: image/jpeg)
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DescriptionAntenne gp vhf 1.jpg |
Français : L'antenne ground plane VHF 156 MHz à 162 MHz ou GPA (Ground Plane Antenna) est un dipôle dans lequel on a remplacé la moitié par un « plan de sol », la moitié conservée étant normale à cette surface. Si le plan de sol est suffisamment grand, le demi-dipôle se comporte exactement comme un dipôle entier (type: dipôle demi-onde λ/2) car sa réflexion dans le plan de sol forme la partie manquante. Dans ce cas, son gain théorique est de 2,14 dBi (où les dBi sont des décibels avec un « i » ajouté pour rappeler qu'il s'agit d'un gain par rapport à une antenne isotrope), la longueur physique est environ égale au quart de la longueur d'onde de la fréquence sur laquelle l'antenne est accordée. Ces brins, disposés en cercle inclinés vers le bas ; en nombre de 3, ils constituent une surface conductrice de l'électricité, même si cette surface n'est pas parfaite pour être alimenté par un câble coaxial de 50 ohms .
English: A VHF ground plane antenna for 156 to 162 MHz. The vertical wire functions as a quarter-wave monopole antenna, while the downward sloping wires serve as a ground plane for the monopole. The downward slope of the ground plane wires serves to increase the characteristic impedance of the antenna to make it a good match for the 50 ohm coaxial cable feedline. |
Date | |
Source | Own work • Self-photographed |
Author | F1jmm |
Licensing[edit]
Public domainPublic domainfalsefalse |
I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. |
This is a retouched picture, which means that it has been digitally altered from its original version. Modifications: picture manager bright. Modifications made by F1jmm.
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 18:49, 9 July 2012 | 1,276 × 1,976 (1.26 MB) | F1jmm (talk | contribs) | éclairage image | |
20:18, 28 September 2010 | 1,276 × 1,976 (1.15 MB) | F1jmm (talk | contribs) | {{Information |Description=antenne Ground plane VHF 156 MHz à 162 MHz |Source={{own}} |Date=2010-09-28 |Author= F1jmm |Permission= |other_versions= }} Category:Monopole antennas |
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Camera manufacturer | Canon |
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Camera model | Canon PowerShot A420 |
Exposure time | 1/1,000 sec (0.001) |
F-number | f/5 |
Lens focal length | 17.3 mm |
Date and time of data generation | 14:06, 16 August 2010 |
Orientation | Normal |
Software used | Adobe Photoshop CS2 Windows |
File change date and time | 22:07, 28 September 2010 |
Y and C positioning | Centered |
Exif version | 2.2 |
Date and time of digitizing | 16:06, 16 August 2010 |
Meaning of each component |
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Image compression mode | 3 |
APEX shutter speed | 9.96875 |
APEX aperture | 4.65625 |
APEX exposure bias | 0 |
Maximum land aperture | 4.65625 APEX (f/5.02) |
Metering mode | Pattern |
Flash | Flash did not fire, compulsory flash suppression |
Supported Flashpix version | 1 |
Color space | sRGB |
Focal plane X resolution | 12,085.106382979 |
Focal plane Y resolution | 12,085.106382979 |
Focal plane resolution unit | inches |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Custom image processing | Normal process |
Exposure mode | Auto exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Scene capture type | Standard |