|[AMRadio] Vertical antennas|
jc at pctechref.com
Fri Nov 6 14:24:19 EST 2015
Well I am not an expert on this type of thing but if I was going to use the
roof as a counterpois / ground plane I would tie all the metal sheets
together electricly with wire straps. The more the better. Bad connections
could cause a lot of arcing that may not even be visable but could cause a
lot of harmful harmonic noise, not to mention loss of radiation power. It
may be more trouble than it is worth! 20 ft above the roof is not very high
for 7 mhz and lower. As for as grounding the roof for lighting, I just
don't know. I have read that lighting rods with pointed ends do acutally
work, as for as bleeding off static build up, but I think they have things
called brushes with lots of wire (like a wire brush that is install at tower
tops and heavy cable run down to the earth that is said to work better. ???
Any way, my thought is to add more tower hight and run dipoles.
From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Jim
On the subject of Verticals, I have just completed a new "tin" roof on my
house. About 3000 sq feet of ground plane...... I am wanting to operate 0n
20 and 40 meters. I have two towers, one on either end of the ridge pole
and about 20 feet higher. Any ideas for an antenna that would take optimal
advantage of the new roof?
Should I run ground cables from the roof to the actual ground? Or would
this draw lightning to my roof? Or would it bleed off the charge and
prevent lightning to my roof? My house is on the TOP of the highest point
on the GultCoast of the US (43' above sea level on a "salt washed bluff")
Any suggestions for an antenna that would make use of the local environment
would be greatly appreciated.
On Fri, Nov 6, 2015 at 10:10 AM, John Coleman <jc at pctechref.com> wrote:
> I haven't seen any post about an end fed zep vertical. I recall that
> K4KYV, used an end fed wire while he was in Houston and it worked
> quite well. I see no reason the same thing couldn't be done
> verticaly. as a matter of fact I have used a vertical 40 meter J-POLE
> (but just made of wire and supported by ballons) at a field day a long
> time ago. It was wonderful.
> I may be mistaken here but I think many AM broadcast station use
> insulated half wave verticals and with a tuner at the base to provide
> instead of current feed. Of course an 80 mtr version may not be feesable
> but a 40 mtr version whoould work for a lot of folks.
> John, WA5BXO
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