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

You don't need to include diode lead length in the quad antenna
calculations.

Thanks, Jeff. Very much appreciated.

Jeff Liebermann wrote:

...
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


SMC sounds good ...

Regards,
JS

Jeff Liebermann wrote:


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
...

Hmmm, perhaps I read him wrong, you ARE correct here ... that
clarification is appreciated.

Regards,
JS

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