V Beam, do they work?
 

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

V Beam, do they work?
 

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

V Beam, do they work?
 

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.

V Beam, do they work?
 

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

V Beam, do they work?
 

On 22 Mar 2006 17:40:02 -0800, wrote:

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??

Tom,

Some questions.

What is "good" gain?

What frequency?

How high?

Try this at 10 MHz. Dimensions in feet.

End 1 End 2

X Y Z X Y Z

W1 0.0 0.0 100.0 245.0 -114.2 100.0
W2 0.0 0.0 100.0 245.0 114.2 100.0

V Beam, do they work?
 

Thanks guys. I tried the models and they still look poor. Let me
explain a bit...

What is "good" gain?

More than a 3 element yagi.

What frequency?

Well, I was trying 160, 80 and 40. I have a 300ft support at one
point, and a bunch of 100ft trees a good distance away across open
fields (maybe 800 feet).

How high?

Anything up to 300 ft at the feedpoint.

Try this at 10 MHz. Dimensions in feet.

That antenna almost equals a three element yagi in gain, but the 3 ele
yagi has a HPBW of 60 degrees. The V beam has a HPBW of 18 degrees. Not
so good. Even if I try two V beams, one inside the other, I can only
get 3dB more gain.

I was wondering if I was missing something, because I keep hearing
stories about how good big V beams work.

V Beam, do they work?
 

V Beam, do they work?
 

I was just reading about them in the antenna handbook. The v-beam is
better than a dipole and is directional, but the same wire bent
half-way out to make a rombic seems to add more gain. you might look
into it.

Buck
N4PGW


On 22 Mar 2006 17:40:02 -0800, wrote:

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

--
73 for now
Buck
N4PGW

V Beam, do they work?
 

V Beam, do they work?
 

On Fri, 24 Mar 2006 12:04:51 -0500, Dave wrote:

wrote:

SNIPPED

It looks like a simple antenna, has a good reputation, but it doesn't
look very useful for anything. Unless there is a combination I'm
missing.

73 Tom


I've never worked with a Vee antenna. But, while stationed at Hill AFB,
Utah we used two of them back to back to make a Rhombic :-) to support
the South East Asia phone patch nets during the Vietnam conflict. Fixed
point to point communication [We had an LP that was used for stateside
COMMs]

My understanding is that a narrow beam is formed along the axis
[centerline] of the Vee. In a standing wave antenna, the beam is
bi-directional. In a terminated antenna, traveling wave, the pattern is
unidirectional. The narrow beam width reduces interference from
undesired directions.

Tom is correct. Vee beams and rhombics have horrible sidelobes that
make them in my estimation highly overrated. The vee is not completely
bi-directional, a couple of dB FB is not uncommon. A vee, just like a
rhombic can be terminated to increase the FB. If the legs are long
enough it -is- a traveling-wave antenna and is somewhat
self-terminating.

The claim for broadband gain is also suspect. There are optimum
parameters that are not frequency independent

Of course I can't fault VK5MC's three-stack rhombic that gave me my
two-meter WAC :-)


Total wavelength and included angle have significant impact on performance.

Of course.