On Jan 11, 2:12 pm, Jim Kelley wrote:
Cecil Moore wrote:
On Jan 10, 9:23 pm, Jim Kelley wrote:
A standing wave is an amplitude vs position envelope.

A standing wave has an associated envelope but the envelope is *NOT*
the wave itself.
It's like saying the body of a car is the car itself but you have
forgotten the thing that makes the car move - the motor.

Sorry, that is a false statement.

No, in the most general sense, it is a precisely accurate statement.

The equation for a standing wave contains an omega*t term. The
equation for standing waves that does not contain an omega*t term is
the equation for the envelope. Quoting the following reference, page
32: "For problems in which we shall be concerned throughout with
sinusoidal quantities, it is not necessary to write the factor e^jwt
explicitly each time, since it will always be understood that all
terms are multiplied by this factor;"

Please reference "Fields and Waves
in Communication Electronics" by Ramo, Whinnery, and Van Duzer, page
343.

Ah. Apparently the only book you know of that contains the
description of a standing wave.

No, just the only book I brought on my trip.

The equation for the standing wave voltage is: Ez = Efor*e^j(wt-
Bz) + Eref*e^j(wt+Bz)

You must belong to the Standing Wave Equation of the Week Club. Nice
letter choices. :-)

Ramo and Whinnery use E+ and E- but that looks too much like addition
and subtraction when using ASCII characters.

Ah. So according to Cecil, we have a new definition for a wave which
now stipulates that it must only be expressed as a function of time.

Nothing new. The actual standing wave equation is a function of time.
Dropping the time term turns it into an envelope equation. An envelope
is a wave envelope, not a wave. You need to learn to be a little more
precise with the language you choose to use. Looks like you have
forgotten that e^jwt is implied. You need to be a little more precise
with your wording.
--
73, Cecil, w5dxp.com