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<div class="moz-cite-prefix">Attached are 2 pix of the ARC and 1 pic
of the Laird sectors. Excuse the mess, these were taken before I
re-organized and cleaned up the lab. :)<br>
<br>
Excellent point about parasitic reflections. I had not considered
that.<br>
<br>
And yeah, I'd love to stick with off-the-shelf. Really don't
wanna get into the business of manufacturing antennas. Wanna
build a network!<br>
<br>
--Bart<br>
<br>
<br>
On 2/6/2013 10:33 PM, Rob Salsgiver wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Bart,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Can
you send me a photo or two of the internals of one of these
sector antennas? I’ve done some work with 2.4 but not 5.8.
I’m curious to know if they are flat panels or if they are
contoured (rounded or otherwise shaped). <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m
thinking along the lines of your sheet metal shields.
Depending on the internal design, I’m wondering if we can’t
apply some different approaches here. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
potential downside of a sheet metal shield is parasitic
reflections, unless they are spaced such that they enhance
the signal (ala a reflector) as well as shield from adjacent
RF.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Using
it as a reflector then gets me thinking of applying some
other geometries – how about a yagi or log periodic design
for 5.8? Given the frequencies involved, it likely would
fit into a similar footprint.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
need to do some calcs and brainstorming. There’s definitely
advantages to having off the shelf equipment, and if
possible it would be good to launch with standard items if
they work, but there may be longer-term advantages to using
some of the benefits of our “amateur” roots if we can get
them to be stable and reliable.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Rob<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
PSDR [<a class="moz-txt-link-freetext" href="mailto:psdr-bounces@hamwan.org">mailto:psdr-bounces@hamwan.org</a>] <b>On Behalf Of </b>Bart
Kus<br>
<b>Sent:</b> Wednesday, February 06, 2013 9:45 PM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:psdr@hamwan.org">psdr@hamwan.org</a><br>
<b>Subject:</b> [HamWAN PSDR] Improved radiation pattern
software and new antennas on the way<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Hello,<br>
<br>
I've taken some time tonight to improve the radiation pattern
measurement software. The algorithm for auto-centering the
rotation of the pattern won't be fooled now by the presence of
a non-centered peak lobe. Full description of the software
function and the software itself have both been published to
the <a moz-do-not-send="true"
href="https://www.hamwan.org/t/tiki-index.php?page=Antenna+Analysis&structure=HamWAN">Antenna
Analysis</a> labs page. The radiation pattern for the <a
moz-do-not-send="true"
href="https://www.hamwan.org/t/tiki-index.php?page=Laird+SAH58-120-16-WB&structure=HamWAN">Laid
sector</a> has been updated and you can see the wonky
alignment is now gone!<br>
<br>
Since neither of these antennas are thrilling performers in
the HamWAN Labs tests, a couple more candidates have been
added to the <a moz-do-not-send="true"
href="https://www.hamwan.org/t/tiki-index.php?page=Sector+Antenna+-+120deg&structure=HamWAN">Sector
Antenna - 120deg</a> component engineering page. A HamWAN
community member who wishes to remain anonymous has generously
purchased sample antennas of the Teletronics and RF Elements
brands for lab testing. They should arrive some time next
week.<br>
<br>
In the meantime, I've had a thought about how to improve F/B
ratios in these sector antennas. Using a sheet of aluminum
and my <a moz-do-not-send="true"
href="http://www.harborfreight.com/30-inch-bending-brake-67240.html">sheet
metal brake</a>, I should be able to manufacture traditional
RF shields, like this:<br>
<br>
<img id="_x0000_i1025"
src="cid:part5.03010006.06050700@bartk.us" alt="VARIA
14-19dBi
variable sector antenna 45-120°, 2.4-2.5GHz"
height="600" width="600" border="0"><br>
<br>
but without fancy holes or adjustable features. It might be
enough to keep that nasty high power adjacent RF out.<br>
<br>
--Bart<o:p></o:p></p>
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