I built this, actually, a while back. Toss in a director (what is one
more wire?); I found that to be a worthwhile mod ...

Regards,
JS

Suggestions re. dimensions and location of a director?

Thanks.

SparkyGuy wrote:
I built this, actually, a while back. Toss in a director (what is one
more wire?); I found that to be a worthwhile mod ...

Regards,
JS

Suggestions re. dimensions and location of a director?

Thanks.


I believe I tried lengths of a 3% to 5% shorter length with the
director, than the drive element (i.e., the one in front of the
reflector), settling on a 4% shorter length ... anyway, that is common
in HF parasitic arrays ... this is equiv. to a 3-element quad on HF.

I just dug it out and measured it, this is what it appears to be,
alright. With a spacing between driven element and director of ~0.2
wavelength, center-to-center.

Regards,
JS

I believe I tried lengths of a 3% to 5% shorter length with the
director, than the drive element (i.e., the one in front of the
reflector), settling on a 4% shorter length ...

So about 26.8mm square?

With a spacing between driven element and director of ~0.2
wavelength, center-to-center.

So the director should be 25 mm forward (toward the uwave source) of the
driven element? (3e8 / 2.4e9) x 0.2 = ~25mm

Do these numbers look right?

Thanks.

SparkyGuy wrote:
I believe I tried lengths of a 3% to 5% shorter length with the
director, than the drive element (i.e., the one in front of the
reflector), settling on a 4% shorter length ...

So about 26.8mm square?

With a spacing between driven element and director of ~0.2
wavelength, center-to-center.

So the director should be 25 mm forward (toward the uwave source) of the
driven element? (3e8 / 2.4e9) x 0.2 = ~25mm

Do these numbers look right?

Thanks.


My elements are made from #14 bare copper wire. It is difficult to
measure each side, individually, when constructing the antenna. Better
to cut the wire to 1 wavelength, then make your bends forming it into a
square. Of course, every attempt possible should be made to keep each
side 1/4 of this length, exactly.

In measuring the one before me, which I constructed, this total length,
about the quad, is ~12.5cm.

However, here is a calculator I referenced in my constructions:

It is a java application, you must have java on your computer. Let me
know if you can't access it and I will give you the figures it spits
out, 2.4ghz = 2400mhz. Just let me know what wifi channel you wish to
center on (frequency.)

Regards,
JS

John Smith wrote:

...
However, here is a calculator I referenced in my constructions:

It is a java application, you must have java on your computer. Let me
know if you can't access it and I will give you the figures it spits
out, 2.4ghz = 2400mhz. Just let me know what wifi channel you wish to
center on (frequency.)

Regards,
JS

Well, da! It would help if I cut loose with the URL. sheepish smile

http://www.n6mrx.com/Antenna/Cubical-Quad1.htm

Regards,
JS

http://www.n6mrx.com/Antenna/Cubical-Quad1.htm

Thanks for the link. The calculator works for me.

One remaining Q: how do I take into account the "pigtails" of the driven
element? A nice square loop is nice, but I've got to connect it to the
(relatively) big diode, and this requires a bit more wire from the loop to
the diode (on the + side of the loop) and to the meter connector (on the -
side). Do I include these wire lengths in the loop size calculation? Or
ignore them?

Or does the 1000pF cap effectively terminate the loop (re. size)?

Thanks.

On Mon, 8 Dec 2008 08:24:55 -0800, SparkyGuy
wrote:

Q: how do I take into account the "pigtails" of the driven
element? A nice square loop is nice, but I've got to connect it to the
(relatively) big diode,

You don't need to include diode lead length in the quad antenna
calculations. The "loop" in the quad driven element is just an LC
tuned circuit. It's as bit less than one wavelength around the loop
and resonated to 2.4GHz by the tuning cap. The diode and other
components do add some capacitance, which will lower the frequency
somewhat, but the adjustment cap is substantially larger than these
capacitances. For example, the off capacitance of a Schottky diode is
about 0.5pf. You do need to keep lead length short as the added
inductance will act as an RF choke.

However, instead of the giant diode, I suggest something smaller and
better, such as a Schottky diode:
http://www.adsemi.com/diodes/schottky_barrier_mixer_detector.shtml
http://www.macom.com/psc/jsp/ListParts.jsp?dataFile=mixing_detector_diodes.txt

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

SparkyGuy wrote:
http://www.n6mrx.com/Antenna/Cubical-Quad1.htm

Thanks for the link. The calculator works for me.

One remaining Q: how do I take into account the "pigtails" of the driven
element? A nice square loop is nice, but I've got to connect it to the
(relatively) big diode, and this requires a bit more wire from the loop to
the diode (on the + side of the loop) and to the meter connector (on the -
side). Do I include these wire lengths in the loop size calculation? Or
ignore them?

Or does the 1000pF cap effectively terminate the loop (re. size)?

Thanks.


You MUST take into consideration every single mm of the loops length!
Leads (apparently "pigtails") ARE the loop ...

But, nothing stops you from being creative. The guy whos'
construction(s) we are following did have about optimum parts to work
with--you will just have to be "creative" ... good-luck.

Warm regards,
JS

SparkyGuy wrote:

...
Suggestions re. dimensions and location of a director?

Thanks.


Had company today, been in and out all day ... sorry I didn't offer more.

A wavelength at 2.4Ghz will be approx. 12cm, half-wave ~6cm, 1/4 wave
~3cm. (with a very thin wire 1/2 wave monopole-omni-element I find
~12.25cm works for me, element dia. will affect this, as other factors ...)

Anyway, I looked though my old emails for something a friend sent me,
thought if you were interested in the 2.4g fsm, you might be interested
in this, if nothing else, just because the dude is so complete!:

http://www.users.bigpond.com/darren....enna_for_2.htm

You will notice, he uses a plate reflector ...

Regards,
JS

On Sun, 07 Dec 2008 21:40:38 -0800, John Smith
wrote:

A wavelength at 2.4Ghz will be approx. 12cm, half-wave ~6cm, 1/4 wave
~3cm. (with a very thin wire 1/2 wave monopole-omni-element I find
~12.25cm works for me, element dia. will affect this, as other factors ...)

Anyway, I looked though my old emails for something a friend sent me,
thought if you were interested in the 2.4g fsm, you might be interested
in this, if nothing else, just because the dude is so complete!:

http://www.users.bigpond.com/darren....enna_for_2.htm

You will notice, he uses a plate reflector ...

Regards,
JS

I also noticed that he cut his elements to a precision of 0.1mm. That
would be correct if the boom were an insulator or the elements were
inserted in insulating sleeves. However, since the 10mm square boom
is metal and effectively "shorts" part of each element, the actual
element length includes part of the diameter of the boom, thus adding
approximately 5mm to each element length (not including the reflector
and driven element). A VSWR sweep test would have shown the problem.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558