Hello Mike,
EZNEC model of a T configuration using a 50 foot vertical section
indicates each leg of the T needs to be 61 feet long (total length of the top
of
the T would be 61 x 2 = 122 feet), and this is based on resonant frequency of
1.82 mhz.
Input impedance will greatly depend on the number of ground radials you
use. With perfect ground you should expect an input impedance of
approximately 12.2 ohms. With an average ground (no radials), you should
expect an
input impedance of around 66 ohms. With ground radials you will have
something in between, and as you add ground radials you will start approaching
the
12.2 ohm value at resonance.
A good way to match the T to your transmission line with very low loss in
the matching network would be through the use of a simple L network.
73's
Don Kirk (wd8dsb)
In a message dated 1/17/2010 10:44:57 P.M. Eastern Standard Time,
mrscience65704@yahoo.com writes:
Now that I can hear very well (Two 2-wire bi-directional Beverages), it's
time for a transmitting antenna. I want to play in the contest during
January 29-31, and time is running out to put up a transmitting antenna. I
don't
have a tower at this time.
I have some trees picked out for a T antenna, between a section of pasture
where it's easy to lay down a lot of radials. I can have a 50' vertical
section.
But I'm having trouble finding what the approx. dimension of the
horizontal portion at the top should be. Any advice would be appreciated!
73,
Mike Waters
W0BTU
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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