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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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