Author Topic: VHF UHF antenna polarization for Comms Security?  (Read 1167 times)

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GreekMan

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VHF UHF antenna polarization for Comms Security?
« on: September 17, 2016, 10:59:30 AM »
in theory one cannot receive a signal when he uses an antenna vertical to the polarizaton plane.
So how about two survival teams talking to each other with the antennas set horizontally?

ghrit

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Re: VHF UHF antenna polarization for Comms Security?
« Reply #1 on: September 17, 2016, 11:52:25 AM »
In a perfect world, theoretical separation of signals depending on polarization would work.  T'ain't a perfect place, and complete horizontal and vertical separation just will NOT be perfect enough to prevent listening.  MAYBE, if the two stations are close enough together, and the power used is low enough, some limited comms security might be achieved.  Just don't count on it, sez  me, and maybe me only.
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Tevin

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Re: VHF UHF antenna polarization for Comms Security?
« Reply #2 on: September 17, 2016, 07:54:16 PM »
I have to agree with ghrit. It will work up to a point but anytime you send RF out into free air you risk having it go places you did not intend. Antennas just aren't that discriminating.

In any technical or engineering field there is the theoretical and there is the real world. Lots of things that are impossible on paper actually work in the real world, and vice-versa.

One way to implement your idea would be to set up the stations, then do field tests. Drive/walk around the area and map out where you get a signal. With some experimenting, you can define the effective comms area. Obviously, this would only work with base stations. You would not have complete security but you would at least know where your signal can be heard.

GreekMan

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Re: VHF UHF antenna polarization for Comms Security?
« Reply #3 on: September 18, 2016, 01:18:49 AM »
of course we are talking of one more level of security.

Also
... but anytime you send RF out into free air you risk having it go places you did not intend.

That reminded me that radiowaves change polarization when they reflect.
So in theory one's buddy will not listen to it, but the BG will!

Scratch that idea off...TNX!

spacecase0

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Re: VHF UHF antenna polarization for Comms Security?
« Reply #4 on: September 18, 2016, 03:33:15 AM »
shifting polarities can mess with people trying to direction find you

Lamewolf

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Re: VHF UHF antenna polarization for Comms Security?
« Reply #5 on: September 22, 2016, 06:47:58 AM »
You need to remember that VHF and UHF signals change polarization each time they bounce off an object, especially UHF !