Rick wrote:
Doesn't the horizontal part of the inverted L need to be as high as
possible for best results? I'd run into the same problems I'm running
into in putting a dipole or inverted V up high enough.

Not exactly. Make the vertical section of the Inv-L
as long as feasible. The vertical section is the
highest current section and therefore has the greatest
effect. Or instead of an Inv-L, make it a T antenna
with a vertical section and a symmetrical top hat.
The symmetrical top hat doesn't do much radiating.

Here's what EZNEC says using VERT1.ez as the reference.
40m 33' Vert1 has -0.04 dBi gain omnidirectional.

16.5'-16.5'Inv-L has 1.04 dBi gain with some directivity.

16.5'-23.5' T antenna has 0.19 dBi gain omnidirectional.
Note: 16.5' = vertical, 23.5' = horizontal top hat.

Performance wise, I don't think you could tell the real
vertical from the T except for the T's lower feedpoint
impedance.
--
73, Cecil, http://www.qsl.net/w5dxp

Cecil Moore wrote:


Performance wise, I don't think you could tell the real
vertical from the T except for the T's lower feedpoint
impedance.
--
73, Cecil, http://www.qsl.net/w5dxp

The T is better if he wants it to act like a DX vertical.
The L is ok, but if the horizontal wire is fairly long,
there will be a good bit of horizontal radiation.
This can be good for a mix of NVIS and DX, but
for DX only, the T is usually better. The T will have
an overhead null the same as a normal monopole.
I'd say most peoples L's on 160 have more horizontal
wire than vertical... :/ I know mine did. I could only
get mine about 45 ft vertical . That left 80-90 ft running
across the backyard. I often feed my coax fed dipoles
as a top hat vertical on 160 by shorting the coax, and
feeding as a vertical. At the moment I have a turnstile on
80m, and a dipole on 40. "6 legs total"
The 4 60 ft wires make a good "X" top hat..
MK

The T is simply a top loaded vertical. The top portion radiates an
insignificantly small amount for the same reason ground plane radials
don't radiate. (Hey, wonder if they act as an "image" mirror to reflect
the signal into the ground?) (That was a joke.) The horizontal portion
of an L antenna radiates like any end fed horizontal wire. If it's low,
most of the radiation is at a high elevation angle.

Roy Lewallen, W7EL

wrote:
Cecil Moore wrote:

Performance wise, I don't think you could tell the real
vertical from the T except for the T's lower feedpoint
impedance.
--
73, Cecil, http://www.qsl.net/w5dxp

The T is better if he wants it to act like a DX vertical.
The L is ok, but if the horizontal wire is fairly long,
there will be a good bit of horizontal radiation.
This can be good for a mix of NVIS and DX, but
for DX only, the T is usually better. The T will have
an overhead null the same as a normal monopole.
I'd say most peoples L's on 160 have more horizontal
wire than vertical... :/ I know mine did. I could only
get mine about 45 ft vertical . That left 80-90 ft running
across the backyard. I often feed my coax fed dipoles
as a top hat vertical on 160 by shorting the coax, and
feeding as a vertical. At the moment I have a turnstile on
80m, and a dipole on 40. "6 legs total"
The 4 60 ft wires make a good "X" top hat..
MK

A few interesting designs at this web site
[http://members.tripod.com/~KE4UYP/index-22.html] may help you.

One is a a linear loaded 1/2 wave inverted L fed at the top of the L
rather than the base.

Another is a top & bottomed hatted, bottom fed L.

Neither design requires radials.

Author includes theoretical radiation patterns & SWR curves.

73

Terry
W9EJO

That's W8EJO, not 9.

Typo.


Harry7 wrote:
A few interesting designs at this web site
[http://members.tripod.com/~KE4UYP/index-22.html] may help you.

One is a a linear loaded 1/2 wave inverted L fed at the top of the L
rather than the base.

Another is a top & bottomed hatted, bottom fed L.

Neither design requires radials.

Author includes theoretical radiation patterns & SWR curves.

73

Terry
W9EJO

Harry7 wrote:
One is a a linear loaded 1/2 wave inverted L fed at the top of the L
rather than the base.

We also haven't mentioned the half-square which
resembles the above.
--
73, Cecil http://www.w5dxp.com

For what it may be worth ..

Roy Lewallen wrote:
The T is simply a top loaded vertical. The top portion radiates an
insignificantly small amount for the same reason ground plane radials
don't radiate. (Hey, wonder if they act as an "image" mirror to reflect
the signal into the ground?) (That was a joke.) The horizontal portion
of an L antenna radiates like any end fed horizontal wire. If it's low,
most of the radiation is at a high elevation angle.

Roy Lewallen, W7EL

wrote:
Cecil Moore wrote:

Performance wise, I don't think you could tell the real
vertical from the T except for the T's lower feedpoint
impedance.
--
73, Cecil, http://www.qsl.net/w5dxp

The T is better if he wants it to act like a DX vertical.
The L is ok, but if the horizontal wire is fairly long,
there will be a good bit of horizontal radiation.
This can be good for a mix of NVIS and DX, but
for DX only, the T is usually better. The T will have
an overhead null the same as a normal monopole.
I'd say most peoples L's on 160 have more horizontal
wire than vertical... :/ I know mine did. I could only
get mine about 45 ft vertical . That left 80-90 ft running
across the backyard. I often feed my coax fed dipoles
as a top hat vertical on 160 by shorting the coax, and
feeding as a vertical. At the moment I have a turnstile on
80m, and a dipole on 40. "6 legs total"
The 4 60 ft wires make a good "X" top hat..
MK


For a long number of years I used a square loop antenna down low to the ground
on HF. It was not fed in the 'usual' place, at the mid-point on the horizontal
wire, either at the bottom of the square loop or on top. I chose to feed it
half way up one of the vertical sides so as to obtain the best results I could
from the vertical radiation for it. That so as to do the best job I could for
40 and 80 meter DX work without going after formal ground plane enhancement and
working the feed point against that, as in ground plane verticals with radials.


In the 40 meter case the lowest horizontal wire was about ten feet or so above
ground level. The actual loop was fed from a coax cable with the ground braid
of the coax tied directly to the loop wire, and the feed match as a gamma match
section using six inch open wire feed insulators for that, plus a series
capacitor made from a cut off piece of coax cable the braid connected to the
braid connect point end of the center wire of the feed coax and the inside coax
wire connected to the gamma match line section. I had pair of three element
quads made this way, with a pair of switched in or shorted wire stubs made from
the same six inch open wire feed lines which if shorted, made that loop a
director, and if opened, made it a reflector. They were supported at right
angles to each other so I had four-way aiming capability here.


You can laugh all you want, but about 270 countries on 40CW confirmed from it
wasn't too bad. And it placed way up there in the DX test single band entries
for a long time from W5 land, which isn't really the easiest place from which
to compete against the East and West coasts of the USA on low bands.


Yes, it was replaced by a four element phased vertical array, with elevated
tuned radials. Which is definitely noisier on receive. But it has the
advantage of being directionally switchable without going outside and getting
on a step ladder four times just to change the fire direction in the middle of
the night, or rain or .. even .. TRW's and twisters in this area of Texas. Of
which there were only twenty tornadoes on the ground in a single day just a
couple weeks ago right around here.






For years now I've wanted to build a low three element rotary vertically fed 40
meter quad to test this against the four square switched phased vertical array
I've used to romp the confirmed 40CW only card count to 321 now. That with
about a level 5 or 6 ground level quality here in sandy pine tree country. But
age, funds, want-to and other more important computer programming work in my
preference list have gotten in the way.


If I ever can get this done I'd dearly love to post the comparative figures on
a real-time real=workem romp! If it wouldn't be too much trouble for someone
interested in this, making a 40 meter wire loop is pretty easy. You only need
a pair of poles to support the top wire. I think you will be pleasantly
surprised how quiet it is and how effective it is, if vertically fed, for
working low band DX stations....


Mike - W5WQN

wrote:
Cecil Moore wrote:
Performance wise, I don't think you could tell the real
vertical from the T except for the T's lower feedpoint
impedance.

The T is better if he wants it to act like a DX vertical.
The L is ok, but if the horizontal wire is fairly long,
there will be a good bit of horizontal radiation.
This can be good for a mix of NVIS and DX, but
for DX only, the T is usually better. The T will have
an overhead null the same as a normal monopole.

You're right but I wasn't talking about the Inv-L above.
When I said "real vertical", I was talking about a
normal 1/4WL monopole. The T and the 1/4WL vertical
have about the same performance if the T's vertical
section is not too short.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
The T and the 1/4WL vertical
have about the same performance if the T's vertical
section is not too short.
--
73, Cecil http://www.w5dxp.com

The closer to a 1/4 wave for the combined vertical
plus top hat wire , the better. You can even improve
farther as far as current distribution if you make it
longer. IE: 3/8 wave total length. That will raise the
max current point up into the vertical section more
towards the top, rather than the bottom. Course,
if you do this, you will need a cap to tune out the
reactance. Like Roy says, the hat radiates little.
Even just two wires is a pretty clean vertical pattern with
little radiation from the hat unless the total length
is so long as to place the current max at the apex
or into the horizontal wires . So I wouldn't get too
carried away with the total length past a 1/4 wave
if I wanted a strictly vertical pattern. When I ran both
an L and a T, the L would often do better at close to
medium distances in the early PM. But the T was
usually better once it stretched out a bit. So most
of the time, I preferred the T. At that time, I also had a
Z dipole, which was better for NVIS than the L.
Now all I have is the "coax dipole" T. I did away with the
others.. The Z dipole was generally the worse of the
three as far as DX. Course, I don't work too much DX
on 160m. I can't hear most of them with my micky
mouse receiving antennas... :/ I've heard W8JI working
stuff that didn't exist here on my radio.. I've pretty
much faced the fact I won't be having a killer 160 setup
until I can get out in the boondocks.
MK