[Waverley ARS] Amateur radio antenna close to TV antenna

[Brad Crowe]

Are TV antenna masts usually earthed?  The few that I have seen have 
not been earthed.

I suspect that providing a nice earth path to ground is only asking 
for lighting to strike?  Should lightning strike in close proximity, 
I doubt that the earth wire would be able to provide totally protect 
delicate electronic equipment? And these may be destroyed in any 
case.  In case of a direct lightning strike I think that the presence 
of an earth wire would be of little benefit.

Any "bright sparks" out there want to comment.

I would like to find a way of having something automatically sense 
the presence of an electrical storm and trip an antenna relay 
switching the antenna to earth rather than to the transceiver when my 
remote station is setup.  Does everyone disconnect their transceivers 
when a lightning storm passes through their QTH?

Mathias you have started an interesting topic.

73 Brad VK2CEC


At 09:15 AM 31/05/2006, you wrote:
>Hello Folks,
>
>After having had much success with my balcony antenna on my 
>neighbour's balcony on the second floor I am keen to find out what 
>difference it would make to place an antenna in the attic or on top 
>of the roof. Yesterday I tried my antenna in the attic with poor 
>results. Repeater signals were weaker than on my balcony, which I 
>attribute towards missing ground on my mobile antenna when it was up 
>in the attic. I will give it another go with some wire leading 
>towards the water pipeline of my neighbour in the second floor.
>
>I also had an antenna technician coming over yesterday. He inspected 
>the attic, checked out the cavity and had a look at the current TV 
>antenna mast. It seems the guywires & turnbuckles of the existing TV 
>antenna mast are in bad shape and he doesn't recommend to put 
>another antenna on top of the existing mast. Instead he suggested to 
>erect a second mast for the amateur radio antenna. Whilst I 
>understand his concern I am afraid that a base 2m/70cm antenna in 
>proximity of the TV antenna at the same height is more likely to 
>cause TVI than an amateur radio antenna on top of a TV antenna. If I 
>am not mistaken the radiation characteristics of a vertical dipole 
>are that directly above and below the antenna there is nearly no 
>wave propagation. Can anyone confirm my theory and would also 
>recommend to better place and base antenna on top of the current TV 
>antenna? If not why would you say that a second mast/antenna 
>shouldn't cause too much trouble?
>
>When the technician had a look at the current TV antenna setup he 
>realised that the current antenna/mast is not earthed. I'd say that 
>is a risky thing to do and I would certainly not want my antenna on 
>top of the roof without earthing. Any comments on missing earthing 
>from your side, folks?
>
>Thanks for your comments in advance.
>
>Salut,
>  Mathias
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