Author Topic: Resonant cavity  (Read 5882 times)

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Re: Resonant cavity
« Reply #8 on: July 10, 2014, 11:01:34 am »
Next question is then: what are microwaves?

Microwaves, Radar

While there are some radar bands from 1,300 to 1,600 MHz, most microwave applications fall in the range 3,000 to 30,000 MHz (3-30 GHz). Current microwave ovens operate at a nominal frequency of 2450 MHz, a band assigned by the FCC. There are also some amateur and radio navigation uses of the 3-30 GHz range. In interactions with matter, microwave radiation primarily acts to produce molecular rotation and torsion, and microwave absorption manifests itself by heat. Molecular structure information can be obtained from the analysis of molecular rotational spectra, the most precise way to determine bond lengths and angles of molecules. Microwave radiation is also used in electron spin resonance spectroscopy.

For microwave ovens and some radar applications, the microwaves are produced by magnetrons.

Of great astrophysical significance is the 3K background radiation in the universe, which is in the microwave region. It has recently been mapped with great precision by the WMAP probe.

Frequencies: 1.6-30 GHz
Wavelengths: 187 - 10 mm
Quantum energies: 0.66 x 10-5 - 0.12 x 10-3 eV

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Re: Resonant cavity
« Reply #9 on: July 10, 2014, 11:11:12 am »
A cavity resonator, usually used in reference to electromagnetic resonators, is one in which waves exist in a hollow space inside the device.
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So the resonant frequencies of resonators, called normal modes, are equally spaced multiples (harmonics) of a lowest frequency called the fundamental frequency. The above analysis assumes the medium inside the resonator is homogeneous, so the waves travel at a constant speed, and that the shape of the resonator is rectilinear. If the resonator is inhomogeneous or has a nonrectilinear shape, like a circular drumhead or a cylindrical microwave cavity, the resonant frequencies may not occur at equally spaced multiples of the fundamental frequency. They are then called overtones instead of harmonics. There may be several such series of resonant frequencies in a single resonator, corresponding to different modes of vibration.
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An electrical circuit composed of discrete components can act as a resonator when both an inductor and capacitor are included. Oscillations are limited by the inclusion of resistance, either via a specific resistor component, or due to resistance of the inductor windings. Such resonant circuits are also called RLC circuits after the circuit symbols for the components.
A distributed-parameter resonator has capacitance, inductance, and resistance that cannot be isolated into separate lumped capacitors, inductors, or resistors. An example of this, much used in filtering, is the helical resonator.
A single layer coil (or solenoid) that is used as a secondary or tertiary winding in a Tesla coil or magnifying transmitter is also a distributed resonator.



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Re: Resonant cavity
« Reply #10 on: July 10, 2014, 16:08:59 pm »
so it was hollow inside

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Re: Resonant cavity
« Reply #11 on: July 10, 2014, 16:28:22 pm »
at least it is clear that the negative is on the outside and the positive on the inside...


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Re: Resonant cavity
« Reply #12 on: July 10, 2014, 17:50:58 pm »
I remember a patent about Φ ratio frequencies from rf waveguides to make hydrogen from water vapour

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Re: Resonant cavity
« Reply #13 on: July 11, 2014, 02:38:09 am »
at least it is clear that the negative is on the outside and the positive on the inside...

why did you conclude that?

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Re: Resonant cavity
« Reply #14 on: July 11, 2014, 08:44:27 am »
at least it is clear that the negative is on the outside and the positive on the inside...

why did you conclude that?

If HF energy is traveling on the outside of a conductor, is leaving the conductor into space, and you want to catch it, want to bounch it in a cavity, it seems to me logic to do that this way....
If you take the outer tube, you might loose at least 50% floating into air or in our case, waterbucket

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Re: Resonant cavity
« Reply #15 on: July 11, 2014, 10:40:41 am »
isnt there a repulsive force between electrons when they stop moving? but between the walls it's different