[AMRadio] I'm not an antenna expert


Brian Carling bcarling at cfl.rr.com
Wed Jan 11 11:53:16 EST 2006


Should work great for close in work, out to about 200-500 miles.

On 11 Jan 2006 at 11:43, John Lawson wrote:

> 
> I don't even play one on TeeVee...
> 
>    So, in advance of a lot of EZNec work (and I don't have the experience 
> with that program to derive much 'good' out of it right now) - I'd like 
> to ask what may seem to be a rather obvious HF antenna question.
> 
>    Due to the usual reasons - my HF antenna is a loop suspended from my 
> backyard fence - approx 430' total, closed loop, 5' off the ground, fed by 
> 450 ohm ladder line back into the shack, using an Ameritron ATR-15 tuner 
> to match the system to my Valiant.  The tuner and transmitter are bonded 
> to a very heavy ground system via an 8' stake less than 3' from the gear. 
> There is no ground system under the antenna, other than that which Nature 
> provided - and with the current winter conditions, the ground is rather 
> wet and conductive.
> 
>    This antenna system exhibits the following SWR:
> 
> 160M - 1.3:1
>   80M - 1.1:1
>   40M -  +3:1
>   20M -   2:1
>   15M -  +3:1
>   10M -  +3:1
> 
>   The tuner capacitors end up being  all-the-way-meshed on the 
> 'misbehaving' bands - not so on 160, 80, and 20.
> 
> 
>    So I'll see Y'all on 3880 and just fergit the rest.   ;}
> 
> 
>    No but seriously folks: obviously the feedpoint resistance is outside 
> the tuner's ability to cope with it at various frequencies.
> 
>    I'm thinking the first unscientific experiment might be to go to the 
> opposite side of the loop from the feedpoint and cut it into a big 
> horizontal bent dipole - mainly because that will take about 45 seconds to 
> accomplish - one of the benefits of having one's entire antenna at 
> ahoulder-height.
> 
>    But I'd like to get some other opinions - I know there's an electrical 
> Pattern here from the info - and I have some other ideas based on that.
> 
>    And no, I can't put up a "real antenna" so I'm pretty much comiited to 
> making this one work as well as I can. Until I move the QTH to somewhere 
> with a few acres and room for Lots of Wire.
> 
> 
>    Cheers
> 
> John  KB6SCO
> 
> 
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