I went out back last night an did some measurements.
I don't have enough room for a 40 meter bobtail so I am counting that out.
About the highest I can get up into the trees is maybe 55 ft. I presently have
a wire vertical with 4 elevated radials that works very well... but I want to
be able to point it in some direction. I was thinking of putting up either the
Half Square to EU (Ed BTW this doesn't require an elablorate ground system) or
putting up anothor vertical and phase them. I can get a cardiod pattern endfire
with 1/4 wl spacing. I could switch this NE/SW manually until I can build up a
switch. Or I can space them 1/2 wl and get a bidirectional pattern NE/SW -
endfire NW/SE broadside and switch then..
I have had up a 40 meter Half Square at this QTH before and it worked great. It
was pointed NW / SE but last spring the county mower guy mowed it down when the
were cutting the grass in the easement behind us ( where I have my antennas) I
ended up just replacing it with the wire vertical.
Bill..
It would be interesting for you to model the 3 el inverted vee wire beam. I am
thinking the verticals might work better because the beam would be too low for
40 meters...
BTW does anyone have experience switching directions in a wire beam using the
stubs ?? There is
an article in QST this month for an 3 el 80 meter wire beam. He is switching
directions using stubs..
Jeff
>
> From: Bill Coleman <aa4lr at arrl.net>
> Date: 2005/10/20 Thu PM 10:46:59 EDT
> To: <ku8e at bellsouth.net> <ku8e at bellsouth.net>
> CC: <secc at contesting.com>
> Subject: Re: [SECC] SS Club Competition - Going for the Gavel
>
>
> On Oct 20, 2005, at 5:06 PM, <ku8e at bellsouth.net>
> <ku8e at bellsouth.net> wrote:
>
> > The 40 meter vertical might change this weekend as I get ready for
> > CQWW SSB.
> > I am thinking of the one following 40 meter antennas depending on
> > how much room I find out I have :
> >
> > 1) 2 Half squares - one pointed NE/SW , the other NW/SE
>
> Do these have to be worked against ground?
>
> > 2) 3 el wire beam to NE - inverted Vees
>
> You'll need to get the apex up 50 feet or more for the pattern to
> become effective.
>
> > 3) 2 el quad - switchable NE/SW
>
> Ditto here. Or you might consider delta-loops. If you have high
> enough supports, these can be easy to tune and very effective.
>
> > 4) Phased verticals - 1/2 wl spacing - switchable broadside/endfire
>
> Radials again.
>
> > 5) Bobtail Curtain to NE/SW, Half square NW/SE
>
> I've decided that for most effective antennas, you're either looking
> for higher supports or putting miles of wire on the ground....
>
> Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr at arrl.net
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
>
|