"Joel Kolstad" wrote in message
...
"amdx" wrote in message
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The gap in the ribbon would be 0.020", but note; in the pictures
a moon shaped piece has been cut from both ends.

This decreases what's otherwise taken as a lumped capacitor right at the
feed point; this is generally undesirable because it lowers the impedance
from the theoretical calcuations.

There are 4 toroids on the coax. These are under a piece of heat
shrink, so I have no idea what material they would be.

Those toroid are a simple but effective balun: Without them, current
that's supposed to return to the inner side of the coax's shield instead
has a choice between that inner side or the outer side. Currents that
flow on the outer side of the coax's shield significantly distory the
radiation pattern. The toroids "work" because they look like inductors
(hopefully big impedances) to single-ended currents (current trying to go
down the coax) while the fields of current going down the center conductor
of the coax in addition to those from the same current going down the
inside of the shield cancel out to (almost) nothing outside the coax and
therefore the ferrite toroids aren't "seen."

Driven element impedance

Well, if you're driving it with 50 ohm coax, it should be realtively close
to 50 ohms at resonance!

I was surprised there was no matching section, I thought a folded dipole
would have a higher impedance than 50 ohms.

What type toroid material would be used at 2.4Ghz, and I'm thinking it would
look resistive at that frequency.

Thanks for the input,
Mike