Shielding antennas
#1
Hi, Is it advisable to shield ferrite antennas which will be going outside?

Jeff
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#2
(2015-01-11, 14:39)orion_jb2001 Wrote: Hi, Is it advisable to shield ferrite antennas which will be going outside?

Jeff
Shielding only prevents "E" signals from entering the ferrites. It has no effect on any magnetic fields. Many of us operate 'unshielded', because we've seen little or no difference. I've a noisy "H" environment so shielding made absolutely no difference for me. Others have required shielding for electric fields. You have to determine what your environment requires.
Shielding won't hurt, but isn't always necessary. Many of us also do not have 'ferrites' outside... many use them inside. E field probe and preamp MUST be outside, away from structures and noise, and a few meters above the earth.... and there is no shielding required, or effective.

Mike

Stations: 689, 791, 1439
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#3
(2015-01-11, 15:12)Cutty Wrote:
(2015-01-11, 14:39)orion_jb2001 Wrote: Hi, Is it advisable to shield ferrite antennas which will be going outside?

Jeff
Shielding only prevents "E" signals from entering the ferrites. It has no effect on any magnetic fields. Many of us operate 'unshielded', because we've seen little or no difference. I've a noisy "H" environment so shielding made absolutely no difference for me. Others have required shielding for electric fields. You have to determine what your environment requires.
Shielding won't hurt, but isn't always necessary. Many of us also do not have 'ferrites' outside... many use them inside. E field probe and preamp MUST be outside, away from structures and noise, and a few meters above the earth.... and there is no shielding required, or effective.

Mike
Is there any method other than "suck it and see" to see if the "environment" you are going to set up is going to be an issue for interference in H or e situations, like getting an am radio to "listen" for electrical interference? Also while we are talking interference, I am more worried about my control unit being located in a room with a few computers etc. I will be using shielded cable etc, will I get much interference from the electrics in that room, both amps, H and E will be on the roof, suitably weatherproofed etc.

Jeff
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#4
There is no way we can evaluate that for you. All of us must go through the optimizing process in our own environment.
This is not a plug and play system, and each location has it's own variables. Call it 'suck it and see' if you wish.
Whatever you determine today may change tonight... or when the seasons change.
It's a hobby, and it takes time to get to know your station, and environment, and only you can go
through the process... Big Grin There should be no issue with the Controller, or even the E amplifier being in
the computer room, if all else is good. There can be issues with H amplifier and antennas in the same room.

Stations: 689, 791, 1439
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#5
(2015-01-11, 17:37)Cutty Wrote: There is no way we can evaluate that for you. All of us must go through the optimizing process in our own environment.
This is not a plug and play system, and each location has it's own variables. Call it 'suck it and see' if you wish.
Whatever you determine today may change tonight... or when the seasons change.
It's a hobby, and it takes time to get to know your station, and environment, and only you can go
through the process... Big Grin There should be no issue with the Controller, or even the E amplifier being in
the computer room, if all else is good. There can be issues with H amplifier and antennas in the same room.

I thought it would be suck it and see... lol . Thanks for the advice. I thought if I was running shielded cable to the roof for the H, I may as well run the second cable for the E and construct the E amps and antenna as well. Is there any specific length of wire or preferable type (I think the suggested is one fairly stiff), for the E field antennae? I am thinking of a system much like as suggested by Egon, wire and pre amp in in a weatherproof fitting.
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#6
(2015-01-11, 17:37)Cutty Wrote: There should be no issue with the Controller, or even the E amplifier being in
the computer room, if all else is good. There can be issues with H amplifier and antennas in the same room.
Can you clarify that last sentence? There can be issues with exactly which components being in the same room? Thanks.

Andrew
Stations: 1075, 1472
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#7
(2015-01-11, 19:07)Andrew.Instone-Cowie Wrote:
(2015-01-11, 17:37)Cutty Wrote: There should be no issue with the Controller, or even the E amplifier being in
the computer room, if all else is good. There can be issues with H amplifier and antennas in the same room.
Can you clarify that last sentence? There can be issues with exactly which components being in the same room? Thanks.

Andrew
The H Field AMP should be connected with shortest possible wire length, right to the loops. You do not want them near computers etc.
The E field probe/Preamp assy is outside, up in the air, far from structures and noise sources. The E probe/preamp assy then connects with coax to the
E field amplifier, which can be right next to the controller, which could be in the same room with computers, etc, if everything is otherwise ok....

All of the above discussions are generally laid out in the forum discussions and in the 'project description' and construction pdf http://www.blitzortung.org/Webpages/inde...=en&page=3

Stations: 689, 791, 1439
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