In article , "Reg Edwards"
g4fgq,regp@ZZZbtinternet,com wrote:

Reflections are functions of TIME, not frequency.

Oliver Heaviside had the right idea long before the invention of the
SWR meter.
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Reg, G4FGQ.

Hello, and the present or absence of reflections in the steady-state (no
transients as one would see when the system is first energized) is by
comparison of an impedance (Zx) at a measurement point to some reference
impedance (Zo). This reference impedance can be associated with the
characteristic impedance of a transmission line or some other system
characteristic. If Zx and/or Zo varies with frequency (has a reactive
component) then the RMS amplitude of the voltage/current reflections also
varies with frequency. We use this property to match Zx to Zo at some
frequency by minimizing the measured reflected voltage (or current or
power).

In the steady-state there is one voltage/current (as seen by an RF
voltmeter or ammeter) placed at the measurement point. We need a
directional coupler (part of a Bird model 43) or impedance bridge
(referenced to Zo) inserted at the measurment point in order to partition
the sampled voltage/current into incident (forward) and reflected waves.
I'm not sure exactly what Reg meant. Sincerely, and 73s from N4GGO,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337