[TowerTalk] 2 element quad on a 17.5' roof tower?

[Kostas Stamatis]

I had mine (LBA quad) on this height (20 feet) for a long time. No problem 
except the high angle. I would say that the ant performs 100% until 5000 km 
and it is working 80% over there. The difference is in distances over 
10000-11000 km where the signals would have been low if you had it at 30 
feet. On 17 feet you will not hear them at all under the same propagation. 
But always exists a better propagation...
73 Kostas SV1DPI

----- Original Message ----- 
From: "Jon Knodel" <jknodel at msn.com>
To: "Tower Forum" <towertalk at contesting.com>
Sent: Wednesday, April 21, 2010 10:34 AM
Subject: [TowerTalk] 2 element quad on a 17.5' roof tower?


>
> I am looking at putting up a decent hf antenna on my 17.5' Glen Martin 
> roof tower.  Apart from yagis, I'm thinking about a Gem Quad or standard 2 
> element quad.  My question is, how much interaction with the roof will I 
> have and how much will it degrade performance with the bottom of the loops 
> being so close to the roof?  I figure the bottom of the 20m loop will be 
> roughly 8' above the roof.  The house is typical wood construction with 
> asphalt shingle roofing.  I've been modeling with EZNEC and can accept the 
> compromise in overall height (take off angle, etc.) but am just not sure 
> what effect the close proximity with the roof will have.  Any help is 
> appreciated.   Thanks.
>
>
>
> N7XW
>
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