Talk:Ivor Catt/Archive 6

message: Kevin???(dont you mean LC), coax or a waveguide (for microwave frequencies) is used in many practical cases, but let's keep to the simple physics of a DC TEM wave step propagated by two straight aerial-like conductors, as the Catt anomaly uses.  We get electromagnetic radiation (radio emission) from a net time-varying current in a conductor.  If you have two such conductors, with each having an inverted form of the signal in the other, they exchange energy which induces the current in the other.  But there is no long distance propagation of this energy due to exact interference, so the coupling is perfect.  This is how the front of the logic step propagates: each conductor causes the current in the opposite conductor by simple electromagnetic radiation due to the time-varying current as it rises.  Catt simply missed out this mechanism, and is now too prejudiced against the mainstream to back these facts.  Best wishes, Nigel 172.203.152.63 23:18, 24 January 2006 (UTC)
replies: text: Both Catts conductors are connected to the battery. Only one of yours is. Therfore yours dont do nothin man!(IMO) (Unless youre talking about electrostatic charge buildup on the lone conductor)- but there again there must be a return path for the current thro' the stray capacitance to the other end of the battery.--Light current 05:24, 25 January 2006 (UTC)

text: Nigel,I dont really understand your reply here. If you say radio is the return path, you must mean it returns thro' the earth, in which case the other end of the gen must be connected to earth. Is that what you mean?--Light current 22:49, 28 January 2006 (UTC)
replies: text: Nigel is, I think, trying to replace "displacement current" with "radio". In this he is trying to follow on from Catt, while at the same time trying to avoid some of the known problems with Catt's arguments. However, he's not managed to see through some of Catt's misconceptions. I have come to the conclusion that Catt has either picked up a very loose and misleading statement from an introductory textbook, or has completely misinterpreted how Maxwell came to derive the additional term to Ampere's equation that is now referred to as "displacement current". -- Kevin Brunt 22:16, 29 January 2006 (UTC)

text: Maxwell realised that there was a mathematical inconsistency that showed up when Ampere's equation was applied to a volume of space that enclosed one of the two plates of a charging capacitor. In particular Maxwell saw that the inconsistency could be fixed by inserting the term we now know as "displacement current", which he derived from exising work (by Kelvin) - the "continuity equation". ([www.cmmp.ucl.ac.uk/~drb/Teaching/PHAS3201_MaxwellsEquationsFull.pdf See this PDF from UCL]) Maxwell, of course, went on to try to interpret displacement current in terms of his "aether". I think that Catt has picked up on the words "current" and "continuity" and convinced himself that physicists claim that the "flow" of displacement current "completes the circuit" - a position that physics has certainly not held since Maxwell's "aether" was abandoned by the start of the 20th Century. Nigel is just following on from this. -- Kevin Brunt 22:16, 29 January 2006 (UTC)
thread_title:  Nigel to LC? 

message: :Both Catts conductors are connected to the battery. Only one of yours is. Therfore yours dont do nothin man!(IMO) (Unless youre talking about electrostatic charge buildup on the lone conductor)- but there again there must be a return path for the current thro' the stray capacitance to the other end of the battery.--Light current 05:24, 25 January 2006 (UTC)
replies: text: Nigel,I dont really understand your reply here. If you say radio is the return path, you must mean it returns thro' the earth, in which case the other end of the gen must be connected to earth. Is that what you mean?--Light current 22:49, 28 January 2006 (UTC)
replies: text: Nigel is, I think, trying to replace "displacement current" with "radio". In this he is trying to follow on from Catt, while at the same time trying to avoid some of the known problems with Catt's arguments. However, he's not managed to see through some of Catt's misconceptions. I have come to the conclusion that Catt has either picked up a very loose and misleading statement from an introductory textbook, or has completely misinterpreted how Maxwell came to derive the additional term to Ampere's equation that is now referred to as "displacement current". -- Kevin Brunt 22:16, 29 January 2006 (UTC)

text: Maxwell realised that there was a mathematical inconsistency that showed up when Ampere's equation was applied to a volume of space that enclosed one of the two plates of a charging capacitor. In particular Maxwell saw that the inconsistency could be fixed by inserting the term we now know as "displacement current", which he derived from exising work (by Kelvin) - the "continuity equation". ([www.cmmp.ucl.ac.uk/~drb/Teaching/PHAS3201_MaxwellsEquationsFull.pdf See this PDF from UCL]) Maxwell, of course, went on to try to interpret displacement current in terms of his "aether". I think that Catt has picked up on the words "current" and "continuity" and convinced himself that physicists claim that the "flow" of displacement current "completes the circuit" - a position that physics has certainly not held since Maxwell's "aether" was abandoned by the start of the 20th Century. Nigel is just following on from this. -- Kevin Brunt 22:16, 29 January 2006 (UTC)
thread_title:  LC to Nigel 

message: Nigel, you appear not to have heard of Mr Fourier and his famous Fourier analysis which says that any repetitive waveform can be represented by a sum of sine and /or cosine waveforms of appropriate amplitude. Now in your experiment, the square wave that you used would have a fundamental plus all the odd harmonics decreasing in amplitude proportional to the harmonic. So when you say 'the flat part doesn't do anything', strictly speaking, you are incorrect or your statement is careless.--Light current 05:36, 25 January 2006 (UTC)
replies: text: Actually, Catt's "TEM step" isn't a "repetitive waveform", which is part of the problem, since it confused what is going on at the step and what is going on either side of it. Nigel has muddled it further by introducing a radio transmitter, so we now have too many things going on at once. -- Kevin Brunt 22:32, 25 January 2006 (UTC)

text: The issue of one conductor versus two has some relevance, because when you stop to consider it properly a TL is merely a conductor with regular properties to make it more convenience to do theory with. A single isolated conductor is a TL, and a lot of what we've been discussing does not really require a TL at all. In fact, if you read the "Lynch IEE version" of the Catt Anomaly, it is clear that the inclusion of the vacuum-spaced transmission line is merely noise, and that all of Catt's "Southern" and "Western" obfuscation is swept away, reducing the Question to "How can current propagate at nearly the speed of light when the individual electrons only move at less 1mm/second?" -- Kevin Brunt 22:32, 25 January 2006 (UTC)

text: When you connect a conductor to a battery, a voltage step propagates down the conductor. Behind the voltage step there is movement of charge - current flows and because charge has moved into a space that was previously uncharged, the charge with the volume of the conductor increases. There is a magnetic field and an electric field associated with the charge. For a TL it regularity means that behind the voltage step the charge remains constant at least until the step reaches the far end. Thus for a TL, ahead of and behind the step the fields are constant. At the step itself the fields are changing so, by Maxwell's equations, the changing magnetic field created an additional electric field, and vice versa. In a normal radio transmitter the antenna is excited by a sinusoidal signal, so that the fields around the antenna are deliberately not constant. Furthermore the antenna is "tuned" to maximise the field strengths at the right times to transfer energy into the desired TEM wave. The more the exciting waveform diverges from a pure sinusoid, the more energy is wasted. -- Kevin Brunt 22:32, 25 January 2006 (UTC)
replies: text: Light current: I use Fourier analysis to convert waveforms (signal strength versus time) into frequency spectra!  The flat part has constant voltage and thus current variation, di/dt = 0.  Therefore there is no radio emission from the flat part, as I said.  Thanks, Nigel 172.212.87.209 15:32, 27 January 2006 (UTC)

text: Light current: yes!  I was breaking down the Catt question into two stages, where the current is rising and where it is steady.  Of course current continues when the rate of increase of current is zero.  The current rises to a peak at ant location along a conductor, then continues flowing at a steady rate, not varying with time.  So once the front with the rising current has passed, the situation is then covered by the ordinary TEM wave treatment.  Nigel 172.212.87.209 18:10, 27 January 2006 (UTC)
thread_title:  LC's comment on (Nigels reply to Kevin 25 Jan )