[HamWAN PSDR] Shields up, captain!

Bart Kus me at bartk.us
Fri Mar 1 02:15:28 PST 2013















And despite all that, the attenuation between TX+RX antennas is still 
65.5dB!  This must be reflections internal to my garage. Gotta re-run 
these measurements outside.

Also, the angles on the shield are too shallow.  I gave it a 130 deg 
opening, but the back is recessed from the active elements of the 
antenna, so this doesn't actually shield as much as it should. It'll be 
fun to see this on the radiation pattern measurement range!  See before 
+ after.  Might have to use a wider shield.  This is 2ft by 1ft sheet.

The bolt pattern won't work for production use.  In real life, if these 
shields are to be used, they'll just hang on via the 2 mounting bolts at 
the very center of the back of the antenna.  You can just see their nuts 
pointing up in the last picture.  Undoing all the other bolts while the 
antenna is inside the radome would permanently break the antenna.  
Spacers would get knocked loose, and you'd have to destroy the radome to 
re-align things.

This antenna is entirely metric.  Horizontal spacing between all bolts = 
6cm.  Spacing between the upper/lower bolts and the inner bolts = 20cm.  
Spacing between the inner bolts = 6.8cm.  Holes are fine with 1/4" 
drill.  Bolts are M10.

--Bart

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