John, The waves on this chain (ladder) configuration of only capacitors and inductors (no resistors) are "traveling" waves not "standing" waves, and there is much "dispersion" (change of "phase velocity' with frequency).
Any wave that is modulated by amplitude or frequency variations, especially by sharp on-off switching of even a "supposed" sine wave, suffers dispersion. The magnitude of dispersion depends on the abruptness of the modulations. The film was made long before the Internet was invented. There is no on-line version or URL link that I am aware of. Gene. ---- Original message ---- >Date: Mon, 31 Jan 2011 14:44:20 -0800 (PST) >From: "John M. Steele" <[email protected]> >Subject: Re: [USMA:49723] Re: [SI] A mole hill into Himalayas >To: "U.S. Metric Association" <[email protected]>, [email protected] > > Gene, > Was there a link or attachment? I don't appear to have >it. > > > Completely guessing at the content, I am assuming > you may have essentially a standing wave in a > (nearly) lossless transmission. > > The laser EDM may be a bit different. The beam has > moderate divergence to assist in aiming. Not all > the energy hits the reflecort (at large distances) > nor does the reflected energy all make it back. > Further the detector would detect the travelling > wave not the composite electric (or magnetic > field). I would expect the transmitted and > reflected beams to have little interaction. Since > the beam is modulated, there may be some dispersion > based on variation of index of refraction with > wavelength. However, the bandwidth of the > modulation is very small. > > However, I am not up to refreshing my waves and > transmission line knowledge. I got the limiting > specs of some EDMs and they made my point. Unlike > interferometry in vacuum, it is not reasonable to > expect errors on the order of wavelength. > > --- On Mon, 1/31/11, [email protected] > <[email protected]> wrote: > > From: [email protected] <[email protected]> > Subject: [USMA:49723] Re: [SI] A mole hill into > Himalayas > To: "U.S. Metric Association" <[email protected]> > Date: Monday, January 31, 2011, 4:37 PM > > John, > > Here is another comment on the errors of optical > devices; > > There is a teaching film showing wave crests > moving to the right while the envelopes of group > pulses simultaneously move to the left; > demonstrating the potential for errors in laser > surveying devices. The configuration for this > demonstration is a chain of discrete capacitors > and inductors. I leave it to our readers to > discover which of these are connected in series > and which, are connected in parallel. > > I showed this film to my students of "Transmission > Lines, Fields, and Waves" in > a routine undergraduate course at the University > of Illinois (in Urbana, IL). > > Gene. > ...
