[Antennas] Antenna Suggestions

2002年5月30日 11:06:53 -0700

I would like to say thanks to George and everyone else for pointing out my
error:-)
I'm not sure why, but it just seemed to me that the best place to feed the
loop would have been the apex. As several folks pointed out, however, this
is not the case.
I'll try feeding the loop on the low side as soon as I get a chance to put
it up. Although, it may be awhile. I likely won't have time this weekend.
Next weekend I'll be Roving in the big June VHF contest. I may get to it
the following weekend. The weekend after that is field day....
Whew, where does the time go????
73
Dan
Dan Evans N9RLA
Scottsburg, IN 47170
{EM78}
IN-Ham list administrator
QRP-l #1269
1/2 of the N9RLA /R no budget Rover Team
Check out the Rover Resource Page at:
http://www.qsl.net/n9rla
----- Original Message -----
From: "George, W5YR" <[email protected]>
To: "Dan Evans, N9RLA" <[email protected]>
Cc: "Dan Martin" <[email protected]>; <[email protected]>
Sent: Wednesday, May 29, 2002 5:33 PM
Subject: Re: [Antennas] Antenna Suggestions
> I feed my loop in the center of the base of the triangle with ladderline
> taken off a right angles to the wire and parallel to the ground at the 10
> ft level.
>> I modeled the antenna with EZNEC and tried several different positions for
> the feed and the best overall for me was the center of the base.
>> Feeding the apex was the worst in terms of pattern and gain, plus
requiring
> a much longer feedline.
>> I strongly suggest modelling your antenna before doing all the work. The
> demo EZNEC program you can download will do this antenna easily and give
> you an education to boot!
>> This is a unique antenna that seems to have the gain of a dipole relative
> to isotropic, but without the lobed pattern, on 20 meters and above.
>> 73/72/oo, George W5YR - the Yellow Rose of Texas
> Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> Amateur Radio W5YR, in the 56th year and it just keeps getting better!
> QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
> Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
>>> "Dan Evans, N9RLA" wrote:
> >
> > Funny how these things happen, but I've been planning to put up an
antenna
> > very similar to the "tilted triangular loop" you fellas have been
> > discussing.
> >
> > Basically, I have 3 trees for supports. The tallest would put the apex
of
> > the triangle at about 60'. The two smaller trees would hold up the wire
at
> > around 30-35'. Two sides of the triangle would be around 80' long, and
> > slope up from 30-35' high to the 60' apex. The low side would be around
40'
> > long, and pretty much flat at the 30-35' height.
> >
> > The problem. I figure the best place to feed this beast is at the apex.
> > But to do this I would have to bring the ladder line down from the 60'
level
> > to about 8 or 10' high, then run the ladder line parallel to the antenna
for
> > about 30' to the shack. I've been told running ladder line parallel to
an
> > antenna is not a good thing.
> >
> > Alternatively, I could feed it in the middle of one of the 80' sides and
> > bring the ladder line straight down about 40' to the shack.
> >
> > What do you guys think?
> >
> > Right now I've been using an 88' dipole about 35' at the center and
sloping
> > down to about 15-20' at the ends. It seems to do a pretty darn good job
for
> > such a low antenna:-)