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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
Indeed- however a similar approach is used in microwave ovens in the form of a rapidly spinning "stirrer". in principle a flat metal sheet would work with relatively low rotational speeds.
Obviously there would be gaps, however for applications where you absolutely need a lightweight antenna it might provide some useful gain.
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
The point of the spinning metal in a microwave is actually to scatter the beam. This minimizes hot spots within the microwave cavity. The same effect could be duplicated with any moving bit of metal, and the scattering effect isn't precise. It serves the same purpose as the moving turntable in a microwave.
I'd have to agree with Harry on this one. A best case result would be substantial scattering of the signal favoring a direction based on where the reflector was at any given time. Yes, some RF would likely be reflected in the direction you wanted, but a vast majority would continue on its merry way which ever direction it started out heading. I think a best case scenario would be a parasitic interaction between the radiator and the reflector (think Yagi) that would generate a somewhat directional, but distorted and constantly changing field.
Compare it to taking a thin strip of polished metal and spinning it in front of a light. Yeah, a little bit of light will be reflected, but the power needed to drive the motor would be much better spent just making the light brighter.
Geometrically Frustrated Registered Member #6
Joined: Thu Feb 02 2006, 04:18AM
Location: Bowdoin, Maine
Posts: 373
Harry is right. You would have a wifi antenna pointing at a piece of wire that was moving around, perhaps scattering it slightly in random directions.
The spinning reflector in some microwaves is just used to move null regions and hot spots around to keep from burning your food in some places and freezing it in others. It provides no gain.
Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
Grr. Yeah, I just saw the horrible glaring error in my cunning plan.
That said, I had considered the possibility that a very coarse grained dish made of thin mesh in a vacuum, charged from a small Tesla coil might make a fairly good approximation of a plasma antenna...
Spinning it would not achieve very much at all, unless the intention here WAS to scatter radiation in all directions.
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"Spin-tenna" ?!
