dipole 11 meters
 

Hi there,
I would like to make a dipole antenna for 11 meters, i have already made a
half wave 2x 2.58 meter but like to try a full
wave antenna 2x 5.17 meters, so far i figured it out is it impossible
because i have to use a balun the say ?.
is there anyone who can help me, or give me a link to make one?
thanks for your help!
Greetings Ed

dipole 11 meters
 

edwin wrote:
... but like to try a full wave antenna 2x 5.17 meters, ...

For maximum gain, you would need an Extended Double Zepp
dipole. It would be approximately 13 meters long fed with
a matching section of 450 ohm ladder-line that is approximately
1.8 meters long. Install ten turns of coax where the coax
connects to the ladder-line. The above lengths would need to
be adjusted, plus or minus, for lowest SWR.

If you really want a full wave antenna, feed it with
approximately 2.5 meters of 450 ohm ladder-line with
ten turns of coax at the coax/ladder-line junction.
--
73, Cecil http://www.qsl.net/w5dxp

dipole 11 meters
 

On Sun, 3 Sep 2006 16:35:52 +0200, "edwin" wrote:

like to try a full
wave antenna 2x 5.17 meters, so far i figured it out is it impossible
because i have to use a balun the say ?

Hi Edwin,

A full wave antenna has no advantage over a half wave. It's mismatch
is very bad. No BalUn is going to fix that.

73's
Richard Clark, KB7QHC

dipole 11 meters
 

Richard Clark wrote:
A full wave antenna has no advantage over a half wave.

Actually, a full wave antenna has a higher maximum
gain over a half wave by about 1.5 dB.

My 40m full wave antenna has a definite advantage
over a half wave. It works very well on 75m. :-)
--
73, Cecil http://www.qsl.net/w5dxp

dipole 11 meters
 

"Richard Clark"
A full wave antenna has no advantage over a half wave.
It's mismatch is very bad. No BalUn is going to fix that.
_____________

The peak, free-space gain of a full-wave linear dipole is about 1.65 dB
greater than that of a 1/2-wave dipole. Its center fed impedance is high,
but can be transformed at its feedpoint to match conventional transmission
lines.

Many AM broadcast stations use a 1/2-wave vertical monopole, which when
working against a very good radial ground system constitutes a full-wave
antenna. They do it to improve their groundwave field compared to a 1/4
wave monopole, and to reduce nighttime interference to their groundwave by
their own skywave.

But maybe the typical amateur operator would not consider these benefits
worth the effort.

RF

dipole 11 meters
 

In article ,
"edwin" wrote:

Hi there,
I would like to make a dipole antenna for 11 meters, i have already made a
half wave 2x 2.58 meter but like to try a full
wave antenna 2x 5.17 meters, so far i figured it out is it impossible
because i have to use a balun the say ?.
is there anyone who can help me, or give me a link to make one?
thanks for your help!
Greetings Ed

Ed, most CB users have vertical antennas and your dipole will be
horizontal and this is not good. You may be better off making a 5/8th
ground plane.

I always wanted to try a simple 11 meter dipole mounted vertical to see
if it would really work. Anyone ever tried one?

dipole 11 meters
 

There is a low impedance feedpoint for a full wavelength 11 meter antenna.
Simply feed it 1/4 wavelength from the end and add an RF choke to the feedline.

------------------------------||----------
||
3 X 2.58 meters || 2.58 meter
feed point

Cecil can tell you the feed system details.

/s/ DD, W1MCE

Richard Fry wrote:

"Richard Clark"

A full wave antenna has no advantage over a half wave.
It's mismatch is very bad. No BalUn is going to fix that.

_____________

The peak, free-space gain of a full-wave linear dipole is about 1.65 dB
greater than that of a 1/2-wave dipole. Its center fed impedance is
high, but can be transformed at its feedpoint to match conventional
transmission lines.

Many AM broadcast stations use a 1/2-wave vertical monopole, which when
working against a very good radial ground system constitutes a full-wave
antenna. They do it to improve their groundwave field compared to a 1/4
wave monopole, and to reduce nighttime interference to their groundwave
by their own skywave.

But maybe the typical amateur operator would not consider these benefits
worth the effort.

RF

dipole 11 meters
 

On Sun, 3 Sep 2006 16:35:52 +0200, "edwin" wrote:

Hi there,
I would like to make a dipole antenna for 11 meters, i have already made a
half wave 2x 2.58 meter but like to try a full
wave antenna 2x 5.17 meters, so far i figured it out is it impossible
because i have to use a balun the say ?.
is there anyone who can help me, or give me a link to make one?
thanks for your help!
Greetings Ed


Ed,

You are collecting the full range of answers here which must be a
little confusing.

It seems that you are talking about horizontally polarised antennas.
That might be a disadvantage if you were working local stations using
vertical polarisation, less a worry for ionospheric paths or where the
other station is also horizontally polarised.

The full wave dipole does have a little gain in some directions, but
understand that power is not created in the antenna, the higher gain
antenna just distributes the energy more in certain directions. The
gain in some direction(s) is at the expense of less gain in other
directions. (BTW, the gain is so little that you are unlikely to
notice it.) Depending on what you want to use it for, the gain /
pattern of a full wave dipole might not be on average better than a
half wave dipole, or an omnidirectional antenna. Indeed, some
omnidirectional vertical antennas might be better for certain
applications.

Richard is right in telling you there is not much in it (though he may
have been a little more emphatic), but centrefeeding a full wave
dipole is a small challenge, but possibly beyond your knowledge and
experience. You can offset the feedpoint, but it is not an ideal
solution either, it that has its disadvantages (skewed pattern, Z50,
feedline coupling because of asymmetry).

If the stuff of antennas is interesting, perhaps you should consider
pursuing an amateur licence?

Owen
--