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mad98ad1
Joined: 08 Sep 2004
Posts: 41
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 19 Oct 2004 5:14 Parabolic Dish Antenna Polarization |
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| What is the basic difference between H & V polarization of a parabolic dish antenna?
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springf2000
Joined: 13 Jun 2004
Posts: 415
Helped: 18
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19 Oct 2004 5:58 Re: Parabolic Dish Antenna Polarization |
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the electric field of H is paraelled with the ground
but the electric field of V is verticled with the ground
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flatulent
Joined: 19 Jul 2002
Posts: 4926
Helped: 328
Location: Middle Earth
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19 Oct 2004 6:18 Re: Parabolic Dish Antenna Polarization |
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| Here are a few additional items. The polarization is controlled by the feed. The dish can be a skeleton type with wires and work almost as well as a solid metal but with much less wind loading. That is if the wires are the same direction as the feed polarization.
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plasma
Joined: 20 Dec 2001
Posts: 587
Helped: 41
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19 Oct 2004 23:28 Re: Parabolic Dish Antenna Polarization |
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Usually waveguide feed in Parabolic Dish. the Polarization direction
Is the same as the direction of the input connector. If the connector perpendicular to ground. the polarization Vertical . if you need horizontal polarization. Just rotate the dish with the feed 90°. And that Only if you have symmetric dish.
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sergio mariotti
Joined: 22 Dec 2003
Posts: 468
Helped: 43
Location: Italy
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20 Oct 2004 10:43 Re: Parabolic Dish Antenna Polarization |
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| plasma wrote: |
Usually waveguide feed in Parabolic Dish. the Polarization direction
Is the same as the direction of the input connector. If the connector perpendicular to ground. the polarization Vertical . if you need horizontal polarization. Just rotate the dish with the feed 90°. And that Only if you have symmetric dish. |
hmmmm.... i don't agree.
For my opinion, the words "vertical" and "horizontal" are relatet to the "orientation" of the E vector with respect the horizont.
The definition is needed for estabilish a communication path; but this definition contain a little misleading, so require that people working at the TX and RX station be sinergic.
In fact, what does "vertical" mean? Think a parabolic antenna with AZ-EL movement capability looking at the meridian position and observing a satellite. Mount the horn according to the "vertical" definition. Now move the AZ, step by step, tracking a star (or some types of satellites) up to it will be set. At that position the TX polarization will be swapped! But the received polarization still remain the same! This non happen using the circular polarization.
This is the main reason why in Radioastronomy and often in satellite communication the circular polarization is used.
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