Roy Lewallen wrote:
A "gain" antenna isn't of much use if the gain is in the wrong
directions.

Buck could get a good idea of the radiation pattern using
EZNEC (even the free downloadable version from www.eznec.com).
--
73, Cecil, http://www.qsl.net/w5dxp


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Please disregard the posting below as I misunderstood Roy's posting was in
reference to a different thread.
Sorry about that
Art
" wrote in message
news:unWae.17625$NU4.2343@attbi_s22...
Interesting comments Roy
But it does utelize the use of dipoles that are not straight but angled.
It is well known that pointed /angled dipoles does have advantages such as
reducing rotational area, reduction of
reactances that can lead to as much extra gain as 1 Db together with a
broader
banded antenna.
In this particular case he has achieved an extra 3 db by stacking.
Your point regarding direction of main lobs is quite important but lessens
in importance if the antenna is rotatable. Unfortunately I searched the
web page of this new antenna but was unable to find any antenna patterns,
which puts one in a "believe it or not" situation regarding its capability
versus claims.
Art

"Roy Lewallen" wrote in message
...
I presume you realize that a 3/2 wave dipole has multiple lobes, with
nulls between. At many or most angles, a half wavelength dipole has
greater gain.

You can get just two narrow lobes from a 3/2 wave dipole by rotating the
wires 30 degrees to form a horizontal "V" having a 120 degree included
angle. I've used this trick with a 40 meter dipole being used on 15
meters -- it doesn't have much effect on the 40 meter pattern. (You'll
see some TV antennas made this way for the same reason -- the high TV
channels are about 3 times the frequency of the low channels.) But again,
if a station isn't in the right direction, you'll do better with a half
wave dipole than a 3/2 wave one.

A "gain" antenna isn't of much use if the gain is in the wrong
directions. In fact, it's worse than a lower gain one, since the higher
gain it gets in a few directions comes at the expense of lower gain in
the remainder.

Roy Lewallen, W7EL

Buck wrote:

When trimmed to SWR, I get less than 1.5:1 on fifteen meters. My
plans are to build a multiband antenna, parallel elements, where each
band is 3/2 wave dipoles and fed with 50 or 75 ohm coax. I haven't
tried this yet, but I would hope I can have a few gain dipole antennas
in a multi-band format.

On Mon, 25 Apr 2005 00:25:22 GMT, "
wrote:

Please disregard the posting below as I misunderstood Roy's posting was in
reference to a different thread.
Sorry about that
Art


Thanks, I was wondering about that.


--
73 for now
Buck
N4PGW

Buck wrote:

Yes, I believe it has four major lobes and a few minor lobes as well.
None are exactly perpendicular to the wire (IIRC).

At 3/2 wavelengths, there are lobes perpendicular to the wire, but
they're down around 4 dB relative to the maximum lobes.

You got me on this one. I haven't looked into the 'V-Beams'. I was
thinking they were 1/2 wave dipoles. TV antennas are also a form or
Log-Periodic aren't they?

The 3/2 wave antenna bent into a "V" with 120 degree included angle is a
form of the "V beam", similar to half a rhombic. As the antenna gets
longer, the angle of the "V" has to get more acute to make the lobes
align. You can use the "V" shaped elements to make a Yagi, log periodic,
or other array. TV antennas are often a combination of those two.

. . .
I realize that the antenna will have nulls and lobes. If possible, I
would want to arrange the antenna in such a way as to use the lobes to
my benefit. Primarily, it is an experimental antenna as much for the
fun of building it as for using it.

Nothing at all wrong with that. It'll be both fun and educational. You'd
also have fun with an antenna modeling program, which would let you see
the kinds of patterns you'll get.

. . .

Roy Lewallen, W7EL

Roy Lewallen wrote:
Absolutely. Most of the comments I made aren't relevant if the antenna
can be rotated.

Now all that needs to be done is figure out how to
rotate a 3/2WL antenna for 160m. :-)
--
73, Cecil, http://www.qsl.net/w5dxp

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Cecil,
That is the exact problem I have with my antenna which comprises of
reflectors only( no directors) that are manipulated in shape to reduce
reactance swings. Expect to have another shot at it sometime this week
It was easier to put up a long boom with 13 elements or a duplicate antenna
where the reflector elements were not manipulated in shape than this present
experimental antenna.
But even a fraction of a dB gain increase becomes an magnet
for a experimentor.
As for your 180 metre form could one not borrow a Tee shaped
crane from a building site and place elements along its boom ?
I'm sure that would be strong enough to rotate in safety.
Regards
Art


"Cecil Moore" wrote in message
...
Roy Lewallen wrote:
Absolutely. Most of the comments I made aren't relevant if the antenna
can be rotated.

Now all that needs to be done is figure out how to
rotate a 3/2WL antenna for 160m. :-)
--
73, Cecil, http://www.qsl.net/w5dxp

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