Antennaware
[Top] [All Lists]

Re: [Antennaware] 160 meter 3/8 wire, steel or copper

To: "K9AY" <k9ay@k9ay.com>
Subject: Re: [Antennaware] 160 meter 3/8 wire, steel or copper
From: "OZ1AXG Flam" <oz1axg.nospam@dxmail.dk>
Date: Thu, 25 Sep 2008 00:06:54 +0200
List-post: <antennaware@contesting.com">mailto:antennaware@contesting.com>
Hi Gary

Yes the distance to the tower has influenced the matching a lot ... besides 
the 22.5 tower theres also two 80 meter sloopers and 1 inverted V 160 meter 
dipole - altogether making the antenna electrical longer. Its a compromise 
to get room for all the stuff up there :=) The 60 KHz difference in 
resonanse frequence, to the calculated values, might be explained by all 
this extra "top loading" capacity.

I will try repacing the wire, the SS wire can then be used as radials :=)

--
OZ1AXG Flam


----- Original Message ----- 
From: "K9AY" <k9ay@k9ay.com>
To: "OZ1AXG Flam" <oz1axg.nospam@dxmail.dk>; <antennaware@contesting.com>
Sent: Wednesday, September 24, 2008 11:44 PM
Subject: Re: [Antennaware] 160 meter 3/8 wire, steel or copper


> Flam,
>
> Based on your description and measurements, I am certain that proximity to
> the tower is affecting the impedance matching. I was able to obtain 
> similar
> results modeling the tower about 30m tall. It will not have much effect on
> radiation, just matching.
>
> With your wire length, the feed impedance would be in the 30-ohm range.
> Ground losses might add several ohms, but would not double the impedance 
> to
> 70 ohms -- that is due to the capacitance between the wire and tower.
>
> At the present spacing, you may not be able to get a 1:1 VSWR with a 
> single
> capacitor, because the extra "capacitor" between tower and wire is part of
> your matching system, raising the feedpoint impedance. With more spacing
> between tower and wire (1.5m or 2m), the effects will be smaller -- and 
> the
> VSWR will not move as much in the wind!
>
> 1.  Like the other guys, I recommend using copper wire for lower loss.
> 2.  Add some short radials (as many you can) to reduce ground loss.
> 3.  If you are able, increase the spacing between antenna and tower.
>
> 73, Gary
> K9AY
>
>
>
>> Hi
>>
>> A question about wire ...
>>
>> I have constructed a 3/8 for 160 meter. I use the tower to support the
>> antenna. It runs 22 meter vertically and then (horisontal for 24,5 meters
>> (i.e. total 46.5 meter). distance from tower is 1 meter.
>> A the base of the antenna it is feed with a serial capacitor of 430 pF (a
>> 330 in parallel with a 100pF : both door noob).
>>
>> Ground is a combination of 4 ground rods and wire (space is limited). 
>> Best
>> swr @ 1860 Khz is 1:1.4. 1:2 bandwidth is app 80KHz. A noise bridse have
>> shown impedans around 70+j1.
>>
>> Currently the wire is 1.5mm stainless steel wire.
>>
>> How much would the antenna be improved if i substitute the SS wire with
>> with
>> 1.5mm braided copper wire?
>> I guess the seial capacitor would change as well ? any idea how much ?
>>
>> Antennewire i use ( steel 40050 and copper: 40051):
>> http://www.wimo.de/cgi-bin/verteiler.pl?url=wireantennas_e.html
>>
>> --
>> OZ1AXG Flam
>
>


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.169 / Virus Database: 270.7.1/1688 - Release Date: 9/24/2008 
6:29 AM


_______________________________________________
Antennaware mailing list
Antennaware@contesting.com
http://lists.contesting.com/mailman/listinfo/antennaware

<Prev in Thread] Current Thread [Next in Thread>