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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