Thread: Vincent antenna
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Old December 7th 07, 04:37 PM posted to rec.radio.amateur.antenna
Keith Dysart[_2_] Keith Dysart[_2_] is offline
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Default Loading Coils; was : Vincent antenna

On Dec 7, 11:21 am, Cecil Moore wrote:

---43.4 deg 600 ohm line---+---10 deg 100 ohm line---open

The Smith Chart does make it clear what is happening.
Here is the math to go with it. The impedance at the
junction of the two lines is:

-j100*tan(90-10) = -j100*tan(80) = -j567 ohms
-j600*tan(43.4) = -j600*tan(43.4) = -j567 ohms

The phase shift at the junction of the two lines is:
80-43.4 = 36.6 degrees

Time permitting, I will work up the phasor diagrams of
the component voltages (or currents) at the junction
where rho = (600-100)/(600+100) = 0.7143


If the 100 ohm line was only 5 degrees long, how
long would the 600 ohm line have to be to obtain
0 ohms at the input?

Would the phase shift at the junction still be
36.6 degrees?

....Keith