True, but supposedly it's easier to let go when you need to mind the chickens or somesuch at 50Hz than 60Hz...
In Kaiser's "Electromagnetic Compatibility Handbook," he does include the human body in an (otherwise?) completely serious table of antennas and their various properties!
(You guys might not have access to this book, as being upwards of 4" thick and heavy enough to double as a hammer it's probably classified as a weapon over there... :-) )
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Not true.
For a given power output, if the circuit is parallel resonant, then
the power supply has to supply the voltage and current required to
drive the tank's resistance.
If it's series resonant, the power supply still has to supply the
voltage and current required to drive the tank's resistance.
I believe that is true, John. The field is radiated by passing current through the *radiation resistance*. It doesn't care how the current comes to be, whether it is due to circulating current or from a source which can supply the current without resonance.
Yes, the tank's resistance plus radiation resistance.
Yes, the tank's resistance plus radiation resistance.
Well, check the radiation resistance vs the system's resistance. In the case of a 60 Hz loop of "reasonable dimensions", you will probably find the radiation resistance to be in the micro-ohms or less. This will give nano-percent efficiency.
By the way, I am assuming we are discussing transverse electromagnetic radiation.
a coil would radiate a (strong) magnetic field with 60 Hz, but a very weak electric field. For an efective radiation of EM waves, you would need the electric and magnetic fields together, with balanced strength. Otherwise the EM waves could not work over larger distances.
The 60 Hz AC magnetic fields have gotten so bad at the place I work, that I now have to schlep the optical pumping apparatus back to my home to test it. (~0.5 milli Gauss line widths at ~10 Gauss fields.) The AC fields are ~1-2 mG in strength. I thought about trying dectect and cancel them over a small area.. but gave it up.
A permanent magnet is analogous to a superconducting coil. But how to build a 60Hz AC permanent magnet? Simple.
Two permanent magnet rods held side by side, with alike poles adjacent, will create an extensive magnetic field in the surrounding volume. But the same two PM rods, if held side by side with unlike poles adjacent, will create no extensive magnetic field, since the adjacent opposite poles cancel out (and the field strength at a distance is ~0)
So, in order to create a "60Hz permanent magnet," spin two PM magnets so they flip end over end. Let them spin in opposite directions. Use maglev to suspend them. Spin them in a vacuum chamber. Friction will be very low, so you can keep them going at 3600RPM by using a small 'kicker' coil. Better use ceramic magnets to avoid inductive braking. Perhaps use magnetized ferrite spheres rather than rods.
Next, create a quarter-wave radiator. Build more of the levitated- bar-magnet devices. And more. Build a vast array which covers thousands of square miles of landscape. If the phases of the flipping ceramic magnets are adjusted, you can have strong N/S poles appearing and vanishing at 60Hz along the border of the array. Or let those poles rotate around the array if you prefer (and radiate circ polarized 60Hz RF.) The output will rival that of a gigantic superconducting loop antenna.
And once the array grows large enough, radiation resistance will start slowing the magnets. You'll have to add more microwatts to each kicker coil.
With even a small version of this device, probably we could use it as the stator of an induction motor, with a large number of spinning squirrel-cage rotors nearby, each running a bit below 3600RPM.
Such a rotor would benefit from having long "antennas" to couple the rotor to the ambient 60Hz b-field, "antennas" in the form of long rods composed of laminated iron sheets, or perhaps clusters of iron cable.
Antennas for picking up Mag-tricity waves!
((((((((((((((((((((((( ( ( (o) ) ) ))))))))))))))))))))))) William J. Beaty Research Engineer beaty, chem washington edu UW Chem Dept, Bagley Hall RM74 billb, eskimocom Box 351700, Seattle, WA 98195-1700 ph 206-543-6195
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