I will confirm Rick's results. Almost the same antenna here -- 30 ft of
tower insulated from ground on my sun deck with a 24 ft aluminum rod
insulated from the top of the tower; the rod fed against the tower with
ladder line.
A non-resonant, non symmetrical, vertical dipole -- works 80 thru 10
with an old Johnson Matchbox. Works everything I can hear and I can hear
plenty.
Jerome - VA7VV
Vancouver
On Wed, 2011-01-05 at 11:58 -0500, Rick - NJ0IP / DJ0IP wrote:
> Jerry, let me throw two things at you:
>
> 1. I think a horizontal loop is a pretty good radiator, straight up.
>
> 2. The vertical dipole antenna I've described has been in use here for
> nearly 20 years, at 3 different home QTH's and countless portable
> operations. On 80m where one would think it is too short to work, I found
> that I was always just as loud working stateside, JA, or VK, etc. on the
> short vertical dipole, as I was on my full size horizontal dipole which was
> only 40 ft. up. Nobody on this earth can convince me I'm wrong because I
> have a logbook full of QSOs to prove it. (don't forget, I was in Germany)
>
> So, if someone tells me they can't get on 80m because they have no room, I
> just say humbug!
>
> You can get a good fiberglass pole, 40 ft long, for about $120 from
> companies like Spiderbeam.
> You can get 100 ft. of openwire (300 ohm or 450 ohm) for probably $35.
> Add 40 ft. of copper wire and you have a good 80m antenna (well 80 thru 10m
> antenna).
>
> While living in Oklahoma (until last week), I used a bigger version.
> Using a 60 ft. Spiderbeam pole, I built my vertical dipole with 30' per
> side.
> On 80m in CQWW CW with about 800w, I was able to work every dx station that
> came up on the DX cluster, be it in Africa, or anywhere else, with just one
> or two calls.
>
> As I said, people highly underestimate how well these antennas work.
> L.B. Cebik W4RNL (SK) didn't. He too was a fan of the vertical dipole.
>
> Actually, the main reason it works so well is because most people use
> antennas on 80m which are worse! Hi
>
>
> I agree, you should have good success with a vertical mounted on the metal
> building.
> I've always wanted to try that but never had the building.
>
> 73
> Rick
>
>
> -----Original Message-----
> From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
> On Behalf Of Dr. Gerald N. Johnson
> Sent: Wednesday, January 05, 2011 11:00 AM
> To: tentec@contesting.com
> Subject: Re: [TenTec] New and Improved Terminology (NVIS origins)
>
>
>
> On 1/5/2011 4:42 AM, Rick - NJ0IP / DJ0IP wrote:
> > Ken,
> >
> > I don't know if the low angle efficiency falls off faster than the high
> > angle radiation.
> > I can't remember ever reading that, but I have probably only read "a drop
> in
> > the bucket" of all there is.
>
> Because of extended ground losses, no antenna has strong radiation
> exactly at the horizon. It can try but that RF gets absorbed.
> >
> > I do know that I changed my attitude about verticals since reading Rudy's
> > papers.
> >
> > I also know that there is no reason to ever use a vertical with
> inefficient
> > ground.
> > Instead I use a vertical dipole, 30 to 40 ft. overall length, fed in the
> > middle with openwire, and matched with a matchbox inside the shack.
> > No radials, yet still has fairly good efficiency.
>
> Good efficiency on 40 and higher bands, but rotten on 160 where a good
> center fed dipole would be 240 feet tall.
> >
> > I can't imagine why people continue to go with the traditional design,
> > except for the case that they are willing to lay down a complex ground
> > system (or 4 elevated radials per band).
>
> I have a metal machine shed 48 x 56', I figure a trap vertical at the
> middle of all that metal won't need longer radials for the low bands to
> work decently. I've used a trap vertical on a 30' diameter steel grain
> bin with super results 40 through 10.
> >
> > 73
> > Rick
> >
> >
> A poor ground plane contributes a poor (e.g. resistive) ground in series
> with the antenna and so while it improves the bandwidth (and often the
> impedance match), it hurts radiation efficiency. But it gets out better
> than no antenna at all.
>
> 73, Jerry, K0CQ
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