Now available: Program COAX_VLF

The behaviour of transmission lines at the lower frequencies is more
complex than it is at HF and above. The effects set in sooner at
higher frequencies on low impedance coaxial transmission lines. They
are affected more at higher frequencies than other types of line.

As frequency is reduced below several hundred KHz the impedance Zo
increases, its impedance angle becomes more negative, and the
propagation velocity decreases. Unusual things happen such as
reflection coefficients being greater than unity and the SWR being
greater at the input end of a line than it is at the load end.

At power and audio frequencies Zo can be an order of magnitude greater
than the nominal HF value, and the angle of Zo aproaches -45 degrees.

It is useful to be aware of the magnitude of such effects. With coax
they can be experienced in small ways at frequencies as high as 2 MHz
or more.

Download program COAX_VLF in a few seconds from website below and run
immediately. Filesize = 48 Kilo-bytes. It is both practical and
educational. Try to fathom out how reflection coefficients greater
than unity can arise.
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Regards from Reg, G4FGQ
For Free Radio Design Software go to
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