Gary,
Look at the current distribution of a quarter wave vertical. You will notice
that most of the current comes from the lower half of the antenna.
By using an inverted L, you still get that high current portion to radiate.
You get most of the efficiency of a quarter wave vertical.
When you cut off the quarter wave length and substitute the coil, you lose the
most effective portion of the radiator.
The other approach is to use top loading (e.g. a top hat of some sort) which
moves the current up the radiator. The flat top of an inverted L is just a
rudimentary top hat.
Ken
On Nov 17, 2011, at 12:19 PM, Gary Slagel wrote:
> Thanks Ken,
>
> I kind of like the loading coil cuz it keeps down the amount of wire in the
> air..... neighbor and xyl concerns! But.... if I thought the L performance
> would be better I'd go that way. Searching the web I found some comments
> from folks that had used both the mk-160 trap/Inverted L solution and the
> loading coil solution and they seemed to prefer the loading coil. But, the
> mk-160 trap comes off the tower at about 25' up making a pretty short
> vertical section. I'd like to figure out a way to get the vertical section
> up 40 to 50 feet... still right next to the hy-tower though. Maybe based on
> one of the 43' antennas that are all over these days. In that case I
> wouldn't be surprised if the L would perform better then the loading coil.
>
> Gary Slagel
> N0SXX
> http://marina.fortunecity.com/sanpedro/351
> From: WA8JXM <wa8jxm@gmail.com>
> To: Gary Slagel <gdslagel@yahoo.com>
> Cc: towertalk@contesting.com
> Sent: Thursday, November 17, 2011 8:21 AM
> Subject: Re: [TowerTalk] Hy-tower Vertical with 160M Vertical next to it
>
> That should work out pretty well. I have had the same thoughts about a
> Hy-Tower if I ever got one.
>
> No problem sharing the radial field. If possible you might increase the
> field, it can only help, especially on 160.
>
> I would go the inverted L direction. If you were just going to run a short
> wire next to the Hy-Tower and use a base loading coil, I wouldn't bother with
> the additional wire, IIRC, Hygain has a 160m loading coil for the Hy-Tower.
> But the inverted L would be a much better solution IMO.
>
> Ken
>
> On Nov 17, 2011, at 10:13 AM, Gary Slagel wrote:
>
> > I've got a Hygain Hy-tower that I use primarily for 80M but it also loads
> > nicely on 10 thru 40. I'm thinking of running a 160M vertical up the side
> > of the hy-tower, supported by the hytower but spaced 6 to 12 inches away.
> > Insulated from the tower of couse. The 160 vertical will be either an
> > inverted L or something with a loading coil somewhere near the center.
> > I'll use the same radial field I"m using with the hy-tower and feed it via
> > a remote antenna switch... MFJ-4712 switch or something like that.
> >
> > Is this worth experimenting with? In particular I'm wondering
> > 1) is there is a problem sharing the radial field and also
> > 2) do I risk messing up the performance of the hy-tower on 80M. It
> > seems to work well now.
>
>
>
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