"Cecil Moore" wrote in message
...
Dave wrote:
you don't even need reflections. a properly terminated piece of wire has
a different current at every point along the wire.

That's true but the attenuation factor in one foot
of wire might be hard to measure. Introduce reflections
and even a lossless wire will vary the current from
max to min every few inches at GHz frequencies.
--
73, Cecil http://www.w5dxp.com

you don't need any loss either. a properly matched lossless line will have
different current at each point along the line.

Dave wrote:
you don't need any loss either. a properly matched lossless line will have
different current at each point along the line.

Different RMS current?
--
73, Cecil http://www.w5dxp.com

Dave wrote:
"You don`t even need reflections. A properly terminated piece of wire
has a different current at every point along the wire."

Instantaneous values, of course. But, proper termination means no
reflection. The only source of variation along a line other than
attenuation is reflection. In a uniform line, attenuation causes a
steady decline of energy as energy travels. With a lossless line,
properly terminated, variation of rnergy along a line is only the phase
produced instantaneois values along the line. These are resolved during
the period of a cycle by the root mean square calculation.

Best regards, Richard Harrison, KB5WZI

"Richard Harrison" wrote in message
...
Dave wrote:
"You don`t even need reflections. A properly terminated piece of wire
has a different current at every point along the wire."

Instantaneous values, of course. But, proper termination means no
reflection. The only source of variation along a line other than
attenuation is reflection. In a uniform line, attenuation causes a
steady decline of energy as energy travels. With a lossless line,
properly terminated, variation of rnergy along a line is only the phase
produced instantaneois values along the line. These are resolved during
the period of a cycle by the root mean square calculation.

Best regards, Richard Harrison, KB5WZI


and what is wrong with instantaneous values? lacking a requirement to talk
in peak, phasor, rms, or some other averaging method it is perfectly valid
to assume instantaneous measurements. and if I remember right we were
talking of measuring current, not energy. and time is a valid parameter
when measuring current, just hook up your o-scope and measure away...
measure that current on each end of a wire, or coil, or coax, with a dual
trace scope and see the difference! throw away that silly-wire-reader thing
and get back to the basics. get a pulse generator and build yourself a
reflectometer and make use of those reflections!

Dave wrote:
and what is wrong with instantaneous values?

Nothing if presented as part of the context,
confusing if not since most people would
assume the context is RMS. Do I have 110v
AC in my house? You can argue that the answer
is "no" but you would need to state the context.
--
73, Cecil http://www.w5dxp.com

Richard Harrison wrote:

Dave wrote:
"You don`t even need reflections. A properly terminated piece of wire
has a different current at every point along the wire."

Instantaneous values, of course. But, proper termination means no
reflection. The only source of variation along a line other than
attenuation is reflection.

The only electromagnetic currents 'flowing' on a transmission line are
the currents which result from the reflected and/or the forward
electromagnetic waves. Neither of these currents varies periodically
along the line (except as noted, instantaneously).

73, ac6xg