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#11
December 15th 10, 12:53 PM
posted to rec.radio.amateur.antenna
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antenna physics question
On Dec 15, 3:47*am, Art Unwin wrote:
On Dec 10, 8:37*am, joe wrote: Art Unwin wrote: *I am sure you also know that only units used by Mawell represent the path to maximum efficiency in radiation as well as the ratio of capacitance to inductance must be *unity. Art KB9MZ....xg Art, You have just mentioned a constraint on antennas that I was not aware of. *Specifically "the ratio of capacitance to inductance must be unity". This is new to me. Please tell me how I go about making capacitance and inductance equal so their ratio can be unity. How do you get the Farads and Henries to cancel out, leaving a dimensionless number. Can you give me some real world examples? joe Joe, *a better insight to my thinking that may help When a member has little or no reactance via cancellation you can use V=I.R. When R becomes exceedingly small the member reaches a critical point and will oscillate When this happens current increases dramatically which therefore increases radiation. If you view the current curve on a dipole the current is of cyclic form whereas in the case where critical resistance is reached the current flow is of a very high value pulse which also drops fairly rapidly until it reaches a low point before it gets to the end of a period. When the element oscillates it has become a mechanical movement BELOW the current path and as can be seen by comparing to water flow the raggednes in terms of cross sectional area of flow has createrd eddy currents which in electrical terms is equal to displacement current as it is the creation of displacement current.or coefficient of discharge This states why magnetics as used *in non equilibrium structures such as the Yagi cannot be as efficient as a Meander form which achieves higher current which propels *or provides for radiation.. What propelled the notion of waves instead of particles is 1 they ignored Gaussian thrust towards equilibrium and 2 turned to the increase in current because of the mechanical "wave" action which only provides change in amplitude which is not enough to provide an acceleration of charge on a *particle resting on water since that requires two vectors.( I say a resting particle where as it was never clear what the "wave" was lifting or where it came from. This because the force required to remove an electron from its element habitat required more force than that was available. ( Gravity is termed as the weaker force in the Std model) The bottom line being, a radiating structure in equilibrium devoid of reactance with low resistance is the only way current over and above that supplied becomes available. By the way the std yagi is not a closed circuit as equilibrium requires because the half wave length floats, where as a full wave or "period" is consistent or in a steady state when "overshoot" occurs. Thus only when it is resonant is it devoid of reactance which limits the bandwidth. In the case of a Meander form the magnetic field is not present in cyclic form allowing for surface current flow for extended periods and is not frequency dependant. As I have stated before, with my antenna current distribution is via a surge with rapid decay which is accepted in RC L circuitry. Hope that clears things up for you Regards Art yup, clear as mud with waves. |
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