V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have found, I am
thinking of 3/4 wavelength on each side with a horizontal separation angle
of either 72 degrees or 120 degrees. I have seen both separation angles
listed as optimum for maximum gain. I was wondering if anyone knew for sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance might
be. I can feed it with ladder line or good coax and a balun but I am not
sure what balun to use or would it be better to use ladder line? I sure
would appreciate any guidance on this antenna project.

Bob
W5QCP

Bob Wood wrote:

V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have found, I am
thinking of 3/4 wavelength on each side with a horizontal separation angle
of either 72 degrees or 120 degrees. I have seen both separation angles
listed as optimum for maximum gain. I was wondering if anyone knew for sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance might
be. I can feed it with ladder line or good coax and a balun but I am not
sure what balun to use or would it be better to use ladder line? I sure
would appreciate any guidance on this antenna project.

Bob
W5QCP

A true V beam is a minimum of one wave per side. And that minimum is not
much of a V beam...I'd have to double check, but with 3/4 wave per leg,
IE: about the same as an extended double zepp, I think you would have
the most gain with it straight like a normal EDZ. appx 5.1 dbi
bidirectional. I bet your gain will drop off if you try to set it up
like a V beam. As far as the feed impedance, it will vary per band. Not
really a major issue. Just treat it like any other balanced antenna fed
with ladder line. If if tunes, fine. If not, you might need to vary tyhe
feedline length a bit. You could feed with coax for a 3/4 wave per leg
antenna, "also 1/4 wave per leg on whatever band.." , but it would be
better to use a ladder line for all band use. MK
--
http://web.wt.net/~nm5k

Thanks for the comments Mark. I do appreciate your taking time to give me
some advice. I only have a limited space around my home so can't put up a
one wave per side. I am currently using a sloping dipole and doing fairly
well but need to improve the reception to cover Texas, Arkansas, Oklahoma
and Louisiana for Navy MARS region nets. I saw an article somewhere that
indicated a V Beam 3/4 wave on a side would provide 3 dB gain over a dipole
in one direction. I will have to research it some more but it is really
difficult to find information on V Beams on the net. If you do discover any
more info I sure would appreciate you sharing it with me. Thanks again,
73, Bob

"Mark Keith" wrote in message ...
Bob Wood wrote:

V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have found,
I am
thinking of 3/4 wavelength on each side with a horizontal separation
angle
of either 72 degrees or 120 degrees. I have seen both separation angles
listed as optimum for maximum gain. I was wondering if anyone knew for
sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance
might
be. I can feed it with ladder line or good coax and a balun but I am
not
sure what balun to use or would it be better to use ladder line? I sure
would appreciate any guidance on this antenna project.

Bob
W5QCP

A true V beam is a minimum of one wave per side. And that minimum is not
much of a V beam...I'd have to double check, but with 3/4 wave per leg,
IE: about the same as an extended double zepp, I think you would have
the most gain with it straight like a normal EDZ. appx 5.1 dbi
bidirectional. I bet your gain will drop off if you try to set it up
like a V beam. As far as the feed impedance, it will vary per band. Not
really a major issue. Just treat it like any other balanced antenna fed
with ladder line. If if tunes, fine. If not, you might need to vary tyhe
feedline length a bit. You could feed with coax for a 3/4 wave per leg
antenna, "also 1/4 wave per leg on whatever band.." , but it would be
better to use a ladder line for all band use. MK
--
http://web.wt.net/~nm5k

Bob

If you are still uncertain about what angle to use for a V with 1/4 waves
per side, you might get alot of insite from how good LPV antennas are
designed. The basic idea used for the LPV depends on the pattern from each
side of the V to combine to provide good directivity at that frequency where
the elements are 3/4 wave long.

Jerry



"Bob Wood" wrote in message
...
V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have found, I
am
thinking of 3/4 wavelength on each side with a horizontal separation angle
of either 72 degrees or 120 degrees. I have seen both separation angles
listed as optimum for maximum gain. I was wondering if anyone knew for
sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance might
be. I can feed it with ladder line or good coax and a balun but I am not
sure what balun to use or would it be better to use ladder line? I sure
would appreciate any guidance on this antenna project.

Bob
W5QCP

Bob Wood wrote:
"I want to put up a 40M V Beam antenna to enhance communication in one
direction only.---I am thinking of 3/4 wavelength on a side with a
horizontal separation angle of either 72 degrees or 120 fegrees."

Arnold B. Bailey catalogs a bidirectional horizontal unterminated Vee in
"TV and Other Receiving Antennas" Ends of the Vee must be terminated in
their surge impedance for unidirectional response. Bailey gives 800 ohms
as surge impedance of the wires in the Vee.

All antennas in Bailey`s catalog are "optimized" for a frequency of 200
MHz (1.5 meters).

The horizontal Vee is center-fed at its apex. So, it opens / closes
toward its best directions, since It is unterminated. It is
bidirectional.

Bailey`s Vee is several wavelengths per side. Its drivepoint resistance
is 160 ohms. Gain is 10 dB. 3-dB bandwidth is 3%. It still behaves as a
standing wave antenna without termination.

The Vee is made from two horizontal 35-foot #10 wires for 200 MHz,
forming an included angle of 35-degrees (21-feet between outer ends).

At 40m, the wavelength is about 27 times that at 1.5m. So, that`s the
scale factor. The wires become about 933 feet long.

The same wire formed into a rhombic is unidirectional if terminated. It
only takes one termination resistor, and the rhombic gives 3 or 4 more
dB gain than the same wires in a Vee. The rhombic is a little shorter
overall than the Vee, too. At 40 meters the rhombic requires about 567
feet overall length and is about half as wide as it is long.

If you can accept a total gain of about only 4 dB, you can have an
antenna with much less wire and space. Two parallel center-fed wires,
each about 1/2-wavelength, and 1/4-wave apart, elevated at about
1/2-wavelength, and connected together with parallel open-wire line in
the plane of the wires will give a drivepoint resistance of near 50 ohms
across either antenna.

Which direction is favored depends on which dipole is fed directly and
which acts as the directly connected reflector. 3 dB bandwidth is 60%,
which is much better than the 3% of the unterminated Vee.

Arnold B. Bailey gives data on page 521 of "TV and Other Receiving
Antennas" for the "Half-Wave Antenna and Connected Reflector". He
credits P.S. Carter, Proc. I.R.E.,vol. 20, p1032, June 1932.

Best regards, Richard Harrison, KB5WZI

Dear Bob Wood W5QCP:
Nice to see a name and call on a question.
Might you be asking about legs of 3 to 4 wavelengths on 40 meters?
Assuming that is the case, what is optimum depends on height and desired
take off angle (TOA) of the max. radiation.
Most often, three masts of a certain height are available and one
needs to deal with the limitations that result.
What are the expected heights of the masts? 73 Mac N8TT

Note that with one more mast, you will have a rhombic antenna, which is
a little better behaved and much more easy to terminate.
--
J. Mc Laughlin - Michigan USA
Home:

"Bob Wood" wrote in message
...
V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have
found, I am
thinking of 3/4 wavelength on each side with a horizontal separation
angle
of either 72 degrees or 120 degrees. I have seen both separation
angles
listed as optimum for maximum gain. I was wondering if anyone knew
for sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance
might
be. I can feed it with ladder line or good coax and a balun but I am
not
sure what balun to use or would it be better to use ladder line? I
sure
would appreciate any guidance on this antenna project.

Bob
W5QCP

Bob,

Unless the antenna is up in the clear, the full gain, F/B, and F/S will not be
realized. You might be better off using 1/4 wavelength per side, rather than
3/4, and get the extra height instead. As to feeding it, open wire line will
work quite well, over a broad frequency range, and be virtually lossless at
even high SWRs negating the need for a balun and the associated problems. Just
one ham's opinion.

73s,

Evan

Bob

If you are still uncertain about what angle to use for a V with 1/4 waves
per side, you might get alot of insite from how good LPV antennas are
designed. The basic idea used for the LPV depends on the pattern from each
side of the V to combine to provide good directivity at that frequency where
the elements are 3/4 wave long.

Jerry



"Bob Wood" wrote in message
...
V Beam antenna question

I want to put up a 40M V Beam antenna to enhance communication in one
direction only. From the limited design information that I have found, I
am
thinking of 3/4 wavelength on each side with a horizontal separation angle
of either 72 degrees or 120 degrees. I have seen both separation angles
listed as optimum for maximum gain. I was wondering if anyone knew for
sure
which angle would produce the best result. Also, and actually most
important, I need to have some idea of what the feed point impedance might
be. I can feed it with ladder line or good coax and a balun but I am not
sure what balun to use or would it be better to use ladder line? I sure
would appreciate any guidance on this antenna project.

Bob
W5QCP

Bob Wood wrote:
"I want to put up a 40M V Beam antenna to enhance communication in one
direction only.---I am thinking of 3/4 wavelength on a side with a
horizontal separation angle of either 72 degrees or 120 fegrees."

Arnold B. Bailey catalogs a bidirectional horizontal unterminated Vee in
"TV and Other Receiving Antennas" Ends of the Vee must be terminated in
their surge impedance for unidirectional response. Bailey gives 800 ohms
as surge impedance of the wires in the Vee.

All antennas in Bailey`s catalog are "optimized" for a frequency of 200
MHz (1.5 meters).

The horizontal Vee is center-fed at its apex. So, it opens / closes
toward its best directions, since It is unterminated. It is
bidirectional.

Bailey`s Vee is several wavelengths per side. Its drivepoint resistance
is 160 ohms. Gain is 10 dB. 3-dB bandwidth is 3%. It still behaves as a
standing wave antenna without termination.

The Vee is made from two horizontal 35-foot #10 wires for 200 MHz,
forming an included angle of 35-degrees (21-feet between outer ends).

At 40m, the wavelength is about 27 times that at 1.5m. So, that`s the
scale factor. The wires become about 933 feet long.

The same wire formed into a rhombic is unidirectional if terminated. It
only takes one termination resistor, and the rhombic gives 3 or 4 more
dB gain than the same wires in a Vee. The rhombic is a little shorter
overall than the Vee, too. At 40 meters the rhombic requires about 567
feet overall length and is about half as wide as it is long.

If you can accept a total gain of about only 4 dB, you can have an
antenna with much less wire and space. Two parallel center-fed wires,
each about 1/2-wavelength, and 1/4-wave apart, elevated at about
1/2-wavelength, and connected together with parallel open-wire line in
the plane of the wires will give a drivepoint resistance of near 50 ohms
across either antenna.

Which direction is favored depends on which dipole is fed directly and
which acts as the directly connected reflector. 3 dB bandwidth is 60%,
which is much better than the 3% of the unterminated Vee.

Arnold B. Bailey gives data on page 521 of "TV and Other Receiving
Antennas" for the "Half-Wave Antenna and Connected Reflector". He
credits P.S. Carter, Proc. I.R.E.,vol. 20, p1032, June 1932.

Best regards, Richard Harrison, KB5WZI