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Author Topic: YAGI AND QUAD TOGETHER  (Read 2327 times)

Posts: 217

« on: December 05, 2012, 02:55:05 PM »

Ihave two towers about 18m high, on one tower a 3 element stepp ir, on second tower a 4 element QUAD  from Cubex, both ant are 5 bands.
I had problems with the stepp ir therefor i bouhgt the quad,i have now fixed the stepp ir ,but not using it much.
I will try to connect both antennas together just for fun,not shure what i need to do that ? the distanse between the two tower/antennas about 50-60m.
(I am not going to stack them .)I know i may not win to much, but would be interesting trying it.
Any ideas how to do it ??

Posts: 17418

« Reply #1 on: December 05, 2012, 04:31:43 PM »

This device might do the job for you:

Connect one antenna to each end and plug it into the transmitter.
Well, you might want to use an antenna tuner.

Posts: 2498

« Reply #2 on: December 05, 2012, 05:23:36 PM »

If they were the exact same model of antenna, spaced properly with a phasing harness and splitter you would see an improvement in gain and directivity. As they are completely different designs, with unknown spacing and with an unknown cable length it is going to be impossible to predict what will happen.

If things were good it would work to your advantage. Probably it will do nothing to help you and either leave you with an antenna radiation pattern that makes no sense or maybe even loss instead of gain in the desired direction.

Give it a whirl, it is a good way to learn. Just do not try to extrapolate one potentially good data point into a generalized opinion about performance.

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
Free space loss (dB) = 32.4 + 20 × log10d + 20 × log10 f

Posts: 1979

« Reply #3 on: December 05, 2012, 11:46:04 PM »

This device might do the job for you:

Connect one antenna to each end and plug it into the transmitter.
Well, you might want to use an antenna tuner.


Shucks--you forgot to add some suggestions for proper aiming of the antennas.

Posts: 217

« Reply #4 on: December 06, 2012, 08:55:38 AM »

I have tried that T connector, and tuner, but result not very good,i think there must be another way to do this .
But thanks for answer.

Posts: 17418

« Reply #5 on: December 06, 2012, 09:17:58 AM »

Hi Torgeir,

I know my original response wasn't a very complete answer, but I didn't have
time to write a complete book on the subject.

The results you get will depend on the direction the antennas are aimed, the
tower heights, alignment, and spacing between them, the feedline lengths
to each antenna, etc.  If you can get everything arranged so the antennas
are in phase when pointing in a specific direction you can get some added
gain and directivity.  If they happen to have a null in that direction they won't
work as well.  To make a system that works effectively in multiple directions
generally will require switching in different feedline lengths or otherwise
changing the relative phase of the signal at each antenna so they combine
in phase in each direction as you rotate the antennas.  The required phase shift
will also vary from band to band.

If you connect the antennas together with a simple T in the shack, there
probably will be one or more directions where they add in phase, and others
where they cancel each other.  You can calculate these bearings (and the
required phase shift for other directions) with the application of simple
geometry if you know the feedline lengths and tower locations.

One problem with the simple T connector is that it doesn't guarantee equal
power into each leg if the two cables present different impedances, and if
both lines are 50 ohms then you have to match a 25 ohm combined load.
There are ways around this, but they can get complicated for multi-band

If you just want to try it out and experiment, then the T connector will
get you started:  the next step is changing the relative phase of the
signals and/or trying different directions to determine the angles where
the signals are in phase.  To make a practical system you will have to
design the phase shift system.

There was an article in one of the early ARRL Antenna Compendiums
called "Line Array of Antennas in Echelon" that described a system of
3 antennas and the combining networks to change the phase as they were
rotated to keep them in phase.  You might find that a good reference.

Posts: 217

« Reply #6 on: December 06, 2012, 12:49:37 PM »

Thank you very much for taking time to answer me, i allready have a good antenna in the Quad ,but you know how we are,we allways want something better hi hi.
I will try and read more about it, i also spoke with Seymore W6CCP about it and he also spoke about an article he red.
So again thanks,i will not spend to much work on it, but fun trying/testing a little.
Torgeir  LA4UOA.
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