The homotenna (homopolar motor + antenna).

[gravityblock]

Sometimes the boxing gloves are too hard to put aside.

This design is yet one more in the stream of homopolar concepts. I have thought about this design a long while ago but my knowledge of electro magnetism was fairly limited back then compared to now. So I just put it on the back burner until recently.

Theory:
For me the holy grail of a homopolar motor was to cheat and somehow break physics "laws" and come up with a single wire piece carrying a current. Specifically this would break Kirchoff current law as there will be current nodes that have current leaving without equal amounts entering and vice versa. But this is called the maxwell correction in "physics".

What i then realized is that a simple dipole antenna is really such a simple wire piece. The only problem is that current has to oscillate, if it didn't you would be stuck with a polarized antenna having an excess positive charge on one end and negative on the other. However there's a problem with this oscillation. More specific for the homopolar crowd, the forward current would torque the magnet one way, but the inevitable return current would torque it the other way...and you end up with a zero net energy from torque.

Concept:
The way I tried to solve this is by electromagnetically shielding one half of the magnet. Make no mistake the shield is not ferromagnetic. It is a simple but preferably good conductor that reflects the electro magnetic wave from the wire. Because the shield is a simple conductor, when rotated with the magnet the field remains is unchanged, as if the magnet was stationary and there was no shield. Because the conductive shield does not shield an unchanging field.

Problems:
The first notable problem is rotation speed. As seen from the animation the magnet rotation has the same frequency as the oscillating current. For good shielding to occur, a good conductor and high frequency are needed. However it is not always practical, perhaps impossible to rotate the magnet at 10 000 Hz (600 000 rpm) which is still relatively low for an oscillating current.

The next problem is a conceptual one. We know electromagnet waves can be reflected off metal surfaces. However in our case we have to ask whether they also have a physical reaction. The worst that could happen is that they somehow cause a counter torque. This means that the wave transfers its momentum in the worst way possible for this concept.

Solution:
The first problem can be easily solved by splitting the shield into more regions around the magnet. The second problem can only be uncovered through experimentation.

In conclusion I always hope I get to experiment with these concepts. But discussion on them can be equally important, I hope I shared something that can lead someone to somewhere.

Why couldn't we cause electromagnetic waves traveling in a medium to undergo total internal reflection at its boundary by striking it at an angle greater than the so-called critical angle to generate evanescent 'vanishing waves'.  An evanescent wave is a near-field wave with an intensity that exhibits exponential decay without absorption as a function of the distance from the boundary at which the wave was formed. Evanescent waves are a general property of wave-equations, and can in principle occur in any context to which a wave-equation applies. They are formed at the boundary between two media with different wave motion properties, and are most intense within one third of a wavelength from the surface of formation. In particular, evanescent waves can occur in the contexts of optics and other forms of electromagnetic radiation, acoustics, quantum mechanics, and "waves on strings".

The 'forward current' would produce a torque in one direction during normal electromagnetic waves and the shielding of the 'return current' could be accomplished by generating evanescent waves while coupling it to an external media for storage or extraction.  The evanescent wave coupling takes place in the non-radiative field near each medium and as such is always associated with matter; i.e., with the induced currents and charges within a partially reflecting surface. This coupling is directly analogous to the coupling between the primary and secondary coils of a transformer, or between the two plates of a capacitor. Mathematically, the process is the same as that of quantum tunneling, except with electromagnetic waves instead of quantum-mechanical wavefunctions.

Gravock