On Thursday 28 March 2002 15:42, Paul Christensen wrote:
> > If there's no termination, there's no power - for power, you have to have
> > a dissipating resistance.
>
> Correct in that the unterminated end of a line presents no load. Without a
> load on the of a transmission line, no power is dissipated.
>
> However, power is being generated and dissipated somewhere. Why? If I
> take my fixed output impedance transmitter and connect to an unterminated
> transmission line, my Bird 43 reads 100-watts of forward power and
> 100-watts of reflected power.
Yes, but the Bird isn't measuring *power*. As Ian said, it's detecting
70.71Vrms forwards and backwards. The meter scale assumes the voltage is
going into a 50R resistor. When it isn't, all the meter tells you is the
voltages, not the powers.
Steve
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