Richard Clark wrote:

On Wed, 01 Dec 2004 21:27:25 -0800, Jim Kelley
wrote:


The confusion I think stems from the contention that any 'reflected
power' (unfortunate nomenclature IMO) is first sourced and then after
reflection returned back into the source, or to a circulator load as the
case may be. The latter case is certainly correct. The former is
phenomenologically problematic.


Hi Jim,

By that same logic it follows that the power "into" the transmission
line was in fact never "into" the line at all but into the circulator
input, and any power finding its way into the circulator load also
never found its way into the line, but was merely reflected at the
circulator/line interface.

A circulator, being in general a three (or four) port directional
device, might have some trouble buying into that logic. ;-) The crux of
the phenomenological problem is that power does not flow or move, nor is
it something that is reflected. Hence Roy's (and Reg's) suggestion that
the voltages and currents resulting from the fields which propagate must
be analyzed. From that analysis (which involves the fields, or V and I,
propagating, reflecting, and interfering in both directions) one can
determine the quantities of energy being absorbed by the effected
dissipative loads in the circuit.

A transmission line circuit which includes a circulator w/load does
indeed provide a mechanism by which a portion of the energy produced by
a source can effectively be reflected from a mismatched load back toward
the generator. On encountering the circulator in the reverse direction,
it is then directed to the circulator load where it can be dissipated.
In a lossey transmission line, that reflected signal will be attenuated
and would in fact increase the total amount of energy the transmission
line dissipates. The amount of energy produced by the generator
increases by the amount lost to the circulator load and the transmission
line. **Absent the circulator, those energy losses would not be
realized - nor sourced.**

The argument that fields "have" or "contain" energy is misdirected and
misapplied. Obviously one can measure a field at each of the electrical
outlets in his house even when nothing is drawing energy from those
outlets. The potential to create a transfer of energy does not
necessarily equate with a transfer of energy. A mechanism must exist
which provides the conduit for a transfer of energy. It is that
mechanism, and the nature of the source and the load which determine the
amount of power being generated and transferred to the dissipating load.

73, Jim AC6XG