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Art Unwin wrote:
On posting part one I finished up with a reference to a full wavelength antenna and we need to talk about this choice of a wavelengrh. Equilibrium comes from Newtons laws where force equals reaction force or upthrust equals down thrust where all forces around a point equals zero. All the masters such as Faraday,Gauss and others based all their discoveries around this notion.. In the last century a frenchman saw this as a period in a occillation of a repetitive nature as being the point where a cycle of events begin again. In other words a full cycle was completed and another cycle started. This Frenchman by the name of Foucault built a large, long pendulum in terms of a hundred feet to deetermine the time of one sequence of events that signifies equilibrium. To his surprise the pendulum not only swung left to right and back it also moved rotaed about the center a slight degree. Minor quibble - the pendulum was a proof, not serendipity. His best known pendulum, at the Pantheon, rotated 11 degrees per hour, making a full circle in a bit less than 33 hours. This meant that there was another force, a rotational force must be at work over and above the two dimensional swing and thus for true equilibrium a period is many times a single to and fro movement. The rotation of the earth was the force. The angular speed could be calculated and proven as: angular speed = 360 * sin (latitude) Which is to say that at the poles, the rotation takes one sidereal day, taking progressively longer as one heads to the equator, at which point the oscillation plane stays fixed. Thisw is analagous to our year system of time where every four years we add a correction to the period of time by summing all these slight incorrection of time as a full day in what we term as a leap year. More precisely, it is a way to correct our calendar system without major disruption. As the ability to measure time became more precise, coupled with the obvious shifting of seasons as the error in the calendar added up, it was a way to correlate the calendar system with as little disruption as possible. So it is a time measurement accuracy issue, coupled with change in the rotation of the earth. The former is the most significant error source. This is the reason for the choice of a full wavelength radiatorl since it represents a single oscillation of its harmonics PLUS this small extra force required to meet equilibrium. Now this is interesting. Does it follow that the radiator therefore needs to change in relation to it's latitude? - 73 de Mike N3LI - |
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