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Old April 1st 07, 01:03 PM posted to rec.radio.amateur.antenna
AndyS AndyS is offline
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First recorded activity by RadioBanter: Jul 2006
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Default Antenna Theory Question


Wimpie wrote: I hope this clarifies the antenna internal resistance.

Best Regards,

Wim
PA3DJS


Andy replies:
Thanks Wim and Tony, for a very well presented explanation of
the Thevinen .... I KNEW it had to coincide with the CAxPdens
numbers, but your post pretty well cleared it up....for me, at
least...

Regarding RFID using re-radiation --- I was the designer of
the TIRIS toll tag system for T I ( at 915 mhz) and the method I used
was
to open and short a dipole in the TAG to send data replies to the
Reader.... The specification required an RCS
(Radar Cross Section) change of 180
sq cm at 915, and that was easy to obtain with a dipole and a
pin diode . ( Actually, the RCS changed too much for the spec,
and I had to pad it down a bit )......

I hadn't considered that an antenna delivering to a matched load
lost it's power by re-radiation .... DUHHHH!!!.... Been building stuff
for 50 years , and that obvious fact just never dawned on me....
So, thanks again....

73, Andy W4OAH