Topband: Asymmetric radials for GP antennas; Just in case others seek what I've just found...

[W2PM]

I have the same experience ..  a number of short radials and a few long ones, but only in a 180 degree pattern because of the lot lines and an ill tempered neighbor.   I have several tower sections unused and placed them at base of vertical, bonded all together and hit a few ground rods per section to bond them too.  That made a significant improvement.

If you recall in the old Stew Perry literature his description of an Inverted L included burying all sorts of heavy metal at base in addition to whatever you can arrange for radials.

Sent from my iPad

On May 17, 2011, at 11:17, "ZR" <zr at jeremy.mv.com> wrote:

> Before I knew better, 30+ years ago, I had a 90' tower with 10-20 yagis 
> shunt fed on 160. It was about 40' from the road on the NE thru SW side so 
> many radials were very short and others ranged up to 120' long. The ground 
> was poor, consisting of deep sand  with just a thin layer of topsoil.
> 
> It worked fair but not well considering I was running 1200W. Most DX 
> contacts required waiting in a long line.
> 
> Then I realized about current being maximum starting from the base and I got 
> a bright idea. At the local garden center I picked up 5 rolls of "rabbit 
> fence" which were 2 x 4" welded and galvanized wire mesh coated in green 
> plastic and were 50 x 4'. I laid these down in a spoke, stripped back some 
> plastic, and soldered the ends to the ground ring at the tower with #12 
> copper wire. I also connected them together at the far end of the overlaps 
> with another ring.
> 
> After retuning the match that antenna kicked butt.
> 
> After a bit of grass seed and fertilizer it was completely out of the way of 
> the lawn tractor in a few months.
> 
> Carl
> KM1H
> 
> 
> 
> ----- Original Message ----- 
> From: "Cormac Gebruers" <ei4hq.mail at gmail.com>
> To: <topband at contesting.com>
> Sent: Monday, May 16, 2011 1:20 PM
> Subject: Topband: Asymmetric radials for GP antennas; Just in case others 
> seek what I've just found...
> 
> 
>> All,
>> 
>> I've been searching for clarity and hard data on the effects of asymmetric
>> radials on radiation patterns and efficiency of a vertical as I'm 
>> installing
>> a 21m vertical for 80/160 and will have to live with a radial system that 
>> is
>> significantly compromised over a 180 degree sector.
>> 
>> I was a bit surprised to "not find" this subject dealt with in any clear
>> decisive way in e.g. the ARRL Antenna Book or ON4UN's otherwise excellent
>> Low Band DXing book (Did I miss it in either publication? If so, just send
>> me a "your an idiot" email and I'll crawl back under my cabbage leaf
>> suitably chastened).
>> 
>> I was surprised as I had always assumed it is something many hams have to
>> deal with unless they are prepared to go on "stealth missions" in the dead
>> of night to lay radials on or under neighbours property (I don't recommend
>> this course of action by the way; I attempted just such a thing once and 
>> got
>> caught. As a mental exercise to occupy you during those quite times when
>> calling CQ on a dead 160m, try explaining your way out of that one).
>> 
>> On the basis that there might be one/some/many out there, who, like 
>> myself,
>> are installing verticals with radial systems that are compromised
>> directionally as well as "length-ways", I just thought I'd share what I
>> found; N6LF's excellent (if not exactly encouraging) summary of the
>> consequences of asymmetrical radials at
>> http://rudys.typepad.com/files/qex-ground-systems-part-7.pdf . It's well
>> worth the read.
>> 
>> I hope to hear you all on the far side of the Summer...
>> 
>> -- 
>> Regards
>> Cormac (EI4HQ)
>> [Cork/UTC+1] NNNN++++
>> http://86.43.106.118/ei4hq/
>> http://www.corkharbourweather.ie
>> _______________________________________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>> 
>> 
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> 
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK