Standing morphing to travelling waves, and other stupid notions
 

A14QJ wrote, quoting Roy:
"Just what is a "wave", anyway?"

Wikipedia says:
"Waves travel and transport energy from one point to another, often with
no permanent displacement (mass transport) of particles in the medium;
instead there are oscillations around almost fixed positions. A
traveling wave varies with both time and distance. Phase
velocity=Lambda(f).
A standing wave remains in a constant position and only may be the
result of interference between two waves traveling in opposite
directions

When two opposed waves cancel, there is no net propagation of energy."

The "Hutchin Encyclopedia" says:
"Nodes (positions of zero vibration) and antinodes (Positions of maximum
vibration) do not move.

Water and EM waves can form standing waves in the same way."

A14QJ also wrote:
"The standing wave is the mathematical sum of forward and reflected
waves. This sum is a superposition wave. The components of the
superposition wave no lonnger exist by themselves;----"

The components are not cancelled. Were that so, the Bird Thruline
Wattmeter could not function and the standing wave would be independent
of the forward and reflected waves. Instead, it is only a manifestation
of interference.

Best regards, Richard Harrison, KB5WZI

Standing morphing to travelling waves, and other stupid notions
 

Richard Harrison wrote:
A14QJ wrote, quoting Roy:
"Just what is a "wave", anyway?"

Wikipedia says:
"Waves travel and transport energy from one point to another, often with
no permanent displacement (mass transport) of particles in the medium;
instead there are oscillations around almost fixed positions. A
traveling wave varies with both time and distance. Phase
velocity=Lambda(f).
A standing wave remains in a constant position and only may be the
result of interference between two waves traveling in opposite
directions

The first sentence says that waves travel. The second describes a wave
which doesn't. Which is it?

When two opposed waves cancel, there is no net propagation of energy."

It's statements like that which make me very leery of Wikipedia.

The "Hutchin Encyclopedia" says:
"Nodes (positions of zero vibration) and antinodes (Positions of maximum
vibration) do not move.

Water and EM waves can form standing waves in the same way."

That's fine and good. But it doesn't define what a wave is.

A14QJ also wrote:
"The standing wave is the mathematical sum of forward and reflected
waves. This sum is a superposition wave. The components of the
superposition wave no lonnger exist by themselves;----"

The components are not cancelled. Were that so, the Bird Thruline
Wattmeter could not function and the standing wave would be independent
of the forward and reflected waves. Instead, it is only a manifestation
of interference.

A Bruene wattmeter circuit measures "forward power" and "reverse power"
just fine simply by measuring the voltage and current at a single point
on the line. It doesn't measure separate forward and reverse waves, but
only the total V and I. Was Bruene more clever than Bird, who you say
can't figure out how to do that?

Roy Lewallen, W7EL

Standing morphing to travelling waves, and other stupid notions
 

Richard Harrison wrote:
A14QJ wrote, quoting Roy:
"Just what is a "wave", anyway?"

Wikipedia says:
"Waves travel and transport energy from one point to another, often with
no permanent displacement (mass transport) of particles in the medium;
instead there are oscillations around almost fixed positions. A
traveling wave varies with both time and distance. Phase
velocity=Lambda(f).
A standing wave remains in a constant position and only may be the
result of interference between two waves traveling in opposite
directions

When two opposed waves cancel, there is no net propagation of energy."

The "Hutchin Encyclopedia" says:
"Nodes (positions of zero vibration) and antinodes (Positions of maximum
vibration) do not move.

Water and EM waves can form standing waves in the same way."

A14QJ also wrote:
"The standing wave is the mathematical sum of forward and reflected
waves. This sum is a superposition wave. The components of the
superposition wave no lonnger exist by themselves;----"

The components are not cancelled. Were that so, the Bird Thruline
Wattmeter could not function and the standing wave would be independent
of the forward and reflected waves. Instead, it is only a manifestation
of interference.

Best regards, Richard Harrison, KB5WZI


PLONK, need I say more ...

JS

Standing morphing to travelling waves, and other stupid notions
 

Roy, W7EL wrote:
"A Bruene wattmeter circuit measures "forward power" and "reverse power"
just fine simply by measuring the voltage at a single point on the
line."

So does the Bird Thruline Wattmeter., and it has been doing so for about
half a century.

It uses the fact that reflection reverses the phase between voltage and
current on a 50-ohm coaxial line. That means forward waves can be
separated from reflected (reverse) waves. Bird designs its measuring
elements to extract a line voltage sample that causes the exact same
meter deflection as does a line current sample.

From a wave traveling in one direction the samples add. From the wave
traveling in the opposite direction, the samples exactly cancel in the
meter. Voila! a directional coupler.

It was A14QJ who wrote:
"The components of the superposition wave no longer exist by
themselves;----".

My reply was:
"The components are not cancelled. Were that so, the Bird Thruline
Wattmeter could not function and the standing wave would be independent
of the forward and reflected waves. Instead it is only a manifestation
of interference."

I don`t have a Bruene wattmeter, but I believe it functions like a Bird
but uses transformers to couple to the transmission line.

Best regards, Richard Harrison, KB5WZI