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Richard,
Since we agree the transmission line setup is substantially linear, I'm not sure we have much to discuss. I do not agree with you on antenna linearity, but that is another subject for another rainy weekend, and I'm not the right person to be discussing that anyway. 73, Glenn |
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Hi. How's about you guys going to Dayton.
I'm sure a Tag Fight could be arranged for you all. Two Pin Falls, Two Submissions,or a KO to decide the winner. Maybe if you all meet face to face, you will come to some common agreement, or this thread wii continue ad nausium. Regards Mike. |
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Richard Clark wrote:
snip SBS and SRS (Stimulated Raman Scattering) would be suitable search engine terms (esp. SBS threshold), but I warn you, they lead to remarkably dense work where only one link in 20 will be accessible. 73's Richard Clark, KB7QHC Thanks. tom K0TAR |
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Richard Clark wrote:
Injecting an electron (current) can achieve the same end. How accurate are your electron position and velocity measurements? -- 73, Cecil http://www.qsl.net/w5dxp |
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Richard Clark wrote:
On Thu, 18 May 2006 19:01:58 -0500, Tom Ring wrote: I had not heard of the Stokes shift, nor the scattering you mentioned. I have some looking up and reading to do. Which, of course, Cecil does not, since it's not a Xerox moment. Hi Tom, It is pretty exotic, it only relates to radiation, reflection, refraction, heat, and conduction, topics that are alien to discussion here in more than TV Guide English it appears. Other difficult concepts include linearity, coherence, mixing, and gain. Stokes shift is the change in frequency due to the non-linear response of a media to excitation. Typically the excitation is a photon interacting with a phonon with radiation scattering following. Injecting an electron (current) can achieve the same end. The effect of power clamping in fiber optic transmission lines is due to SBS (Stimulated Brillouin Scattering) threshold. I've been working with this (Stokes and Anti-Stokes Shift) for some 20 years, and it fails easy access through a copier. The mention came only response to questions of linear response to what at first glance would be a rather pedestrian transmission line definition, but Glenn appears to have followed the clown instead of pursuing his own question - he warned me it may have been pointless. SBS and SRS (Stimulated Raman Scattering) would be suitable search engine terms (esp. SBS threshold), but I warn you, they lead to remarkably dense work where only one link in 20 will be accessible. 73's Richard Clark, KB7QHC Hi Richard, Stokes' law and the Raman effect can be found in physics texts dealing with quantum mechanics. Georg Joos, in his book _Theoretical Physics_ deals with such things. The reading is dense but the underlying concepts aren't too difficult. The difficulty might lie in understanding how they apply to this discussion. 73, Tom Donaly, KA6RUH |
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On Fri, 19 May 2006 15:08:11 GMT, "Tom Donaly"
wrote: Stokes' law and the Raman effect can be found in physics texts dealing with quantum mechanics. Georg Joos, in his book _Theoretical Physics_ deals with such things. The reading is dense but the underlying concepts aren't too difficult. The difficulty might lie in understanding how they apply to this discussion. Hi Tom, Certainly Joos would give some entry into the field, but finding work as accessible outside of a bookstore or library (in other words, through a search engine) makes for drinking out of a fire hose to quench a sip's worth of thirst. Insofar as HOW this applies, I've spoken to that and Tom shows interest. That alone goes beyond the typical churning that passes for discussion. The point is that these underlying concepts are fairly simple as you imply and they are certainly not remote from the usual topics of consideration here. What they lack is specifics that relate to our common applications, and there too I've offered discussion. However, few seem inspired to travel those paths and that fault can hardly be laid at my doorstep. 73's Richard Clark, KB7QHC |
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Richard,
Who, in your estimation, does qualify to discuss it? I would like to hear from someone who has actually measured the linearity of a simple antenna. I have not done this, so would only be one guy with an opinion. Plenty of us around. By 'simple antenna' I mean an antenna such as a wire dipole without traps, baluns or other things that could degrade linearity. Since the linearity of antenna systems in general is in question, the simplest setup that answers the question would be best. In the absence of measurement, can anyone comment on the modelling software? Does it assume and model a linear system? If so, do we know of any substantial nonlinear departures from the modelling software? Anyone? 73, Glenn AC7ZN |
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Richard Clark, KB7QHC wrote:
"Who. in your estimation, does qualify to discuss it?" If it`s about antennas, I nominate Kraus. If it`s about mathematics, many marhematicians qualify. In algebra, y = mx + b, (the point slope formula), is called linear because it is the graph of a straight line. In the discussion of transmission lines and antennas, you must admit that a uniform transmission line enforces a unique characteristic impedance (a resistance) on energy traveling in either direction. A resistance is linear because Ohm`s law prevails. In free-space, everyone agrees the characteristic impedance is about 377 ohms (a resistance). Kraus says on page 2 of his 1950 edition of "Antennas": "Let the transmission line now be connected to a dipole antenna as in Fig.1-2. The dipole acts as an antenna because it launches a free-space wave. However, it may also be regarded as a section of transmission line (see Sec. 1-2). In addition, it exhibits many of the characteristics of a resonator, since energy reflected from the ends of the dipole gives rise to a standing wave on the antenna. Thus a single device, in this case the dipole, exhibits simutaneously properties characteristic of an antenna, transmission line, and a resonator. Best regards, Richard Harrison, KB5WZI |
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