"Reg Edwards" wrote

Reflections are functions of TIME, not frequency.

Oliver Heaviside had the right idea long before the invention of
the SWR meter.
====================================

For "reflections" also read "Echos".
====================================

The reason there are so many misunderstandings about SWR is that SWR
meters are based on impedance and frequency. Not a simple concept.

Whereas reflections (echos) (which according to Cecil are what it's
all about) are functions of time and distance. With which we are very
familiar.

Unfortunately, there does not appear to be a simple measuring
instrument which could replace the SWR meter. Any ideas?

But we would still need an instrument, a TLI, which indicates whether
or not the transmitter is correctly loaded with 50 ohms. So perhaps
things are best kept as they are.

Just rename the SWR meter!
-----
Reg, G4FGQ.
====================================

Ric,
Yet again, like a Catherine Wheel, you are flying off in convoluted
tangents.
-----
Punchinello

On Wed, 23 Aug 2006 02:10:41 +0100, "Reg Edwards"
wrote:

Ric,
Yet again, like a Catherine Wheel, you are flying off in convoluted
tangents.

How else to follow your logic? As you can see, facile diversions are
easily managed in kind. ;-)

If you cannot reconcile distance to reflection, what use is it being
preserved in unzipped code? I await your next turn on the highway to
avoid this road-kill.

To cut the thread short, I recall one of your bedtime fairy tales of
how you fought a radar fire aboard an airplane. Cut it anyway you
want, but the fire undoubtedly arose from a mismatch. This appears to
have marked a trauma in your youth to avoid the discussion of mismatch
consequences.

Please, in the future, begin your posts with "Once upon a time..."
instead of
At risk of being called a Troll,
You must agree, this particular bait was self-fulfilling; and as
always, I am most pleased to serve your bidding.

73's
Richard Clark, KB7QHC

Owen Duffy wrote:
Cecil Moore wrote:
and the reflections from a complimentary impedance discontinuity

What is a "complimentary impedance discontinuity", or even a
"complementary impedance discontinuity" if you meant that?

Sorry about the misspelling. I was trying to us the word
"complement" in the sense of "A numerical derived from a
given numeral by a specified subtraction rule. Often used
to represent the negative of the number represented by the
given numeral." Definition from "The IEEE Dictionary".

For instance, the reflection coefficient at the second impedance
discontinuity can be considered to be the complement of the
reflection coefficient at the first impedance discontinuity.

--------Z01---x---Z02---y---Z01-----------

The physical reflection coefficient at point 'x' would be
(Z02-Z01)/(Z01+Z02). The physical reflection coefficient at point
'y' would be (Z01-Z02)/(Z01+Z02). Mathematically, those two
reflection coefficients can be considered to be complements of
each other.
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly wrote:
What's a "complimentary impedance discontinuity," Cecil?

Sorry my spellchecker didn't catch that. It should have
been "complementary", a mathematical term. Please see
my reply to Owen.
--
73, Cecil http://www.qsl.net/w5dxp

Reg Edwards wrote:
Reflections are functions of TIME, not frequency.

Remember that in the (2*pi*frequency*time) term used
to describe reflections, frequency is just as important
as time.
--
73, Cecil http://www.qsl.net/w5dxp

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.
-----
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

J. B. Wood wrote:
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.

Hi John, one important fact that some people would like to
forget is that the reflected wave can indeed be partitioned
from the forward wave. Some people on this newsgroup argue
that the forward wave and reflected wave are inseparable and
that reflected waves contain no rearward traveling energy.

However a circulator plus load resistor located at the source
will prevent reflected wave energy from being incident upon
the source and will heat up that load resistor in the process
proving that reflected waves are real and do contain energy.

My favorite illustration of such is a one-second lossless
transmission line with reflections. The number of watts in
the forward wave plus the number of watts in the reflected
wave equals the number of joules stored in the line during
steady-state. For instance, if Pfor = 200w and Pref = 100w,
then 300 joules of RF energy exist in the one-second long
lossless line during steady-state.
--
73, Cecil, http://www.qsl.net/w5dxp

In article , Cecil Moore
wrote:

Hi John, one important fact that some people would like to
forget is that the reflected wave can indeed be partitioned
from the forward wave.

Hello, and it would be more correct to say that the forward and reflected
waves are components of a standing wave.

However a circulator plus load resistor located at the source
will prevent reflected wave energy from being incident upon
the source and will heat up that load resistor in the process
proving that reflected waves are real and do contain energy.

Hmm. Don't quite get that. Say an RF voltage source is located at port A
of an ideal 3-port circulator designed for a system (characteristic)
impedance of Zo. A load of ZL terminates port B and a load of Zo is
attached to port C. Now, incident energy from the source at A is
transferred by circulator action to the load at port B. If ZL is not
equal to Zo then reflected energy from port B is transferred to port C
where it is dissipated in the port C termination. None of the reflected
energy originating from port B ever returns to port A in this ideal case
(circulator has infinite isolation). Sincerely,

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

Cecil Moore wrote:

Hi John, one important fact that some people would like to
forget is that the reflected wave can indeed be partitioned
from the forward wave. Some people on this newsgroup argue
that the forward wave and reflected wave are inseparable and
that reflected waves contain no rearward traveling energy.

However a circulator plus load resistor located at the source
will prevent reflected wave energy from being incident upon
the source and will heat up that load resistor in the process
proving that reflected waves are real and do contain energy.

Hi Cecil

How much energy is "in the reflected wave" without a circulator load
resistor?

73, ac6xg