"Roy Lewallen" wrote in message
...
I'll once again separate the "antenna" from the "transmission line" to
make it easier to see what's happening.


Okay! I did it!

I didn't separate out the transmission line from the antenna. Instead, I
just modeled the folded monopole. I plotted on a Smith chart the resultant
terminal impedance as the vertical element varied from .23 wavelengths to
..245 wavelengths. It went from (73.31 - J 40.81) through (85.71 + J 0.7908)
to (93.59 + J 22.56). Easy!

I found that a vertical element of .2325 wavelengths gave me 76.05 - J 30.27
ohms. That's a sweet spot for this particular antenna in that feeding it
with a .143 wavelength piece of 75 Ohm coax will match to a 50 Ohm source.

To further my education, I also checked the anti-resonance point you
mentioned.

Thanks!

John