wrote in message
oups.com...
I've been modeling V beams off and on for a few years now, and never
can seem to get one that has useful gain.

Has anyone seen a successful model anyplace of a two or three wave V
with good gain??

73 Tom

Hi Tom,
I have a model of a 5 wavelength 24MHz Vee beam in AO- I can send the file
if it is useful to you. AO reports 11dBi free space gain. Included angle
appears to be 44 degrees.

Dale W4OP

Dale Parfitt wrote:
wrote in message
oups.com...
I've been modeling V beams off and on for a few years now, and never
can seem to get one that has useful gain.

Has anyone seen a successful model anyplace of a two or three wave V
with good gain??

73 Tom

Hi Tom,
I have a model of a 5 wavelength 24MHz Vee beam in AO- I can send the file
if it is useful to you. AO reports 11dBi free space gain. Included angle
appears to be 44 degrees.

I don't have AO Dave, so a description will work.

That sounds like the problem I am seeing. With a 3-5 WL long V, I have
about the same gain as a three element Yagi. But I'll still try to
model your antenna with 5wl legs and 44 degree angle. Thanks.

wrote in message
oups.com...

Dale Parfitt wrote:
wrote in message
oups.com...
I've been modeling V beams off and on for a few years now, and never
can seem to get one that has useful gain.

Has anyone seen a successful model anyplace of a two or three wave V
with good gain??

73 Tom

Hi Tom,
I have a model of a 5 wavelength 24MHz Vee beam in AO- I can send the
file
if it is useful to you. AO reports 11dBi free space gain. Included angle
appears to be 44 degrees.

I don't have AO Dave, so a description will work.

That sounds like the problem I am seeing. With a 3-5 WL long V, I have
about the same gain as a three element Yagi. But I'll still try to
model your antenna with 5wl legs and 44 degree angle. Thanks.

Hi Tom et al,

This is from the AO library:
F=24.94

The vertex is at the origin: 0,0
X,Y of 1st leg is 185.44', -74.92' #12 wire
X,Y of 2nd leg is 185.44', 74.92' #12 wire

Fed at the origin and modeled in free space

AO reports
Z= 255- J706
Forward gain= 11.34dBi
F/B 2.70dB


Hope this is useful,

Dale W4OP

Dear Tom:

It appears that you are investigating a slopping, V-beam with a feed point
at about 90 meters and an operating frequency of, say, 1.82 MHz. When first
used some 80 years ago, V-beams were horizontal (or, alternatively, entirely
in a vertical plane). Two more 90 meter poles are not likely to be in the
picture.

The good news is that you are apparently interested in a narrow range of
frequencies. That is good news because aligning the lobes with their
changing polarization and orientation over a significant bandwidth is like
composing something to compete with Mozart.

Even using one frequency, it is a bear to get a slopping V to do one's
bidding. I would limit lengths to integer multiples of 0.5L that could fit
your farm. I would optimize a single, end fed wire (over ground) and in the
process find a narrow range of lengths that look promising and that fit your
site. Then add, and drive, the second wire. Iteration is called for. I
would use a figure of merit that is the gain at a TOA of something like 30
degrees.

Kraus, even in the first edition, presents several approximate equations
to optimize a horizontal rhombic. They may give a little guidance. I think
I read a Technical Report in the mid 60s on measurements of a sloping V put
out by either NBS or ESSA. I seem not able to put my finger on it just now.

As mentioned, the difficulty with sloping wires is finding a "good"
bore-site addition of fields from the two wires when those fields are, to a
first approximation, in the shape of cones with changing polarization. It
is more easy with horizontal wires.

If I live long enough to retire from teaching, this is a type of project
that would be interesting to investigate. But I only have 42 years in and
my good wife is certain that I could not stand the pace of retirement. Do
let us know what you come up with. Good luck.

73, Mac N8TT

Two side notes: My friend, HS and University classmate, and great DXer
W8TWA has used a set of sloping V-beams on HF to good effect. -- As you know
better than almost anyone, one needs a height in the neighborhood of 2L to
get serious signals from a horizontally polarized antenna at the lower TOAs
used for DX. You may find that your best sloping V-beam has a strong
vertically polarized component in the main beam.