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" <[email protected]> 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" <[email protected]> > To: <[email protected]> > 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 >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 10.0.1375 / Virus Database: 1500/3642 - Release Date: 05/16/11 >> > > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
