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Re: [TowerTalk] Omni Antenna on the side of the tower

To: <kip@kdream.com>, "Tower and HF antenna construction topics." <towertalk@contesting.com>
Subject: Re: [TowerTalk] Omni Antenna on the side of the tower
From: "Gene Smar" <ersmar@verizon.net>
Reply-to: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Date: Mon, 18 Jan 2010 17:07:43 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Kip:

     Extending your LMR400 from 3 to 8 feet will result in an increase in 
loss at 2.5 GHz of about 0.3 dB.  (See 
http://www.timesmicrowave.com/cgi-bin/calculate.pl for a calculator.)  I 
doubt this will appreciably decrease your coverage.

     OOT (One other thing):  Are you planning on installing another 
Polyphaser on the POE cable to protect the router's guts from lightning 
coming in via that cable?  It's just a thought.

73 de
Gene Smar  AD3F

----- Original Message ----- 
From: "Kipton Moravec" <kip@kdream.com>
To: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Sent: Monday, January 18, 2010 2:30 PM
Subject: Re: [TowerTalk] Omni Antenna on the side of the tower


> So 5' should be enough. Since we are using a WRT54GL we do have
> diversity so we could put one on each side.
>
> The concern at 5 feet is now length of coax (although not as bad as
> tower screwing SWR). We are probably looking at 8 feet, and I normally
> like to keep under 4-5 feet because of the losses at 2.4 GHz.  I have 3
> feet of LMR400 to polyphasor then 18" of LMR100 to the router in a
> weatherproof box on the tower. I run weatherproof Ethernet cable (with
> POE) down the tower.
>
> Thanks,
>
> Kip
>
> On Mon, 2010-01-18 at 13:03 -0500, Gene Smar wrote:
>> Kip:
>>
>>      In my field experience with side-mounting omni antennas, I typically
>> ask for at least two WL away from the tower.  This is easier to achieve 
>> with
>> higher-freq sticks.  If you can get this antenna five feet or more from 
>> the
>> steel, you should see feedpoint impedance at spec. You will, however, see
>> some signal blockage through the tower - it's unavoidable but not
>> significant enough to reduce coverage to zero.
>>
>>
>> 73 de
>> Gene Smar  AD3F
>>
>>
>> ----- Original Message ----- 
>> From: "Kipton Moravec" <kip@kdream.com>
>> To: <towertalk@contesting.com>
>> Sent: Monday, January 18, 2010 10:14 AM
>> Subject: [TowerTalk] Omni Antenna on the side of the tower
>>
>>
>> >I was asked how far from the side of a tower should a omni antenna be to
>> > not get too distorted/affected by the metal in the tower.
>> >
>> > I need a practical answer so Infinity will not work. :)
>> >
>> > I am certain it is a function of wavelength. And my antenna is for 2.4
>> > GHz. It is 15 db gain Omni, about 4 feet tall (if that makes a
>> > difference.)
>> >
>> > Kip
>> > -- 
>> > Kipton Moravec AE5IB .- . ..... .. -...
>> >
>> > "Always do right; this will gratify some people and astonish the rest."
>> > --Mark Twain
>> >
>> >
>> > _______________________________________________
>> >
>> >
>> >
>> > _______________________________________________
>> > TowerTalk mailing list
>> > TowerTalk@contesting.com
>> > http://lists.contesting.com/mailman/listinfo/towertalk
>>
>> _______________________________________________
>>
>>
>>
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>>
> -- 
> Kipton Moravec AE5IB .- . ..... .. -...
>
> "Always do right; this will gratify some people and astonish the rest."
> --Mark Twain
>
>
> _______________________________________________
>
>
>
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