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Old December 12th 04, 12:17 PM
Reg Edwards
 
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The following details will give you some idea of what you are waffling
about.

A 2-WIRE, WIDE-SPACED, POWER TRANSMISSION LINE.

At a frequency of 60 Hz

Length = 100 miles.
Wire diameter = 1 inch.
Wire spacing = 10 feet.

Nominal RF Zo = 650 ohms.
Actual Zo at 60 Hz = 650 ohms.
Angle of Zo = -2.6 degrees.

Velocity factor = 0.99
1/4-wavelength = 767 miles.
Resonant Q at 60 Hz = 11

Inductance = 3.54 milli-henrys per mile.
Capacitance = 0.00836 micro-farads per mile.

FOR A LOAD OF 500 OHMS -

Input impedance = 520 + j*51
Line loss = 0.1 dB.
Power Loss in line = An economical 2.3 percent.

Reflection coefficient = 0.133
Angle of reflection coefficient = 170 degrees.
VSWR = 10.5

Economics rules the roost at power frequencies.

The normal transmission voltage on such a line is measured in terms of
100,000 volts.

Note that, with a resonant Q of 11, should an open-circuit fault occur at a
distance of 1/4-wavelength the voltage at the fault can rise to a million
volts or more. Electrical power engineers have far worse problems than mere
radio engineers have on the popular 40m band. They too are concerned with
reflection coefficients and SWR. ;o)

But the technicalities were all exactly sorted out in the Victorian age by
the young, self-educated, recluse and hard-of-hearing genius like
eethoven - Oliver Heaviside who was derided by the old-wives and silly guru
university professors of his age.

The above technical details, and more, can be computed and studied, from
power frequencies up to UHF, by downloading, practical, easy-to-use programs
RJELINE2 or 3 from the following website. Download in a few seconds, not
zipped-up, and run immediately under common-or-garden DOS/Windows.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........




 
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