Is it possible to generate a beating wave ?

Not directly, AFAIK. You could receive it with an antenna, beat it with another signal using a mixer and retransmit it.

Leon

I'd like to do it in a free spectrum. do they have to come from the same antena source ? Are there any similar applications ?

Giorgis

col> > Is it possible to generate a beating electromagnetic wave ?

In message , Leon writes

Of course it's possible - 2 transmitters on the same frequency will produce a beating wave. This technique is used in quasi-sync mobile radio networks to produce wide area coverage where the beat frequency is normally arranged to be a few kHz so that it is above the audio range but still within the receiver capture range.

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Ed Douglas

2 waves of slightly different frequency will beat together if thats what you mean ? therefore you just need to generate and transmit 2 such frequencies.

Colin

I dont know what your application is so I cant answer.

Colin =^.^=

You, of course, mean that two different frequency signals can beat together within the detector of an appropriate receiver. Without a detector, they don't "beat."

Don

Question is more subtle than that.

If two waves are to interact and produce sum and difference frequencies, a nonlinear media or component is required.

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Don Lancaster                          voice phone: (928)428-4073
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I don't think that's what he meant. He is asking whether two waves can beat without a receiver, I don't think that they can.

Leon

Maybe my knowledge is a bit hobbyish in the field. What I would like to do is create an elctromagnetic wave that has a carier wave on it that appears to travel along it at a speed of my choosing.

I suspected that if add two waves to each other that have a very close freequency, I will get the wave of my choice

YES ... NO ?

Giorgis

Take a wave and split it into two streams. They will be of the same amplitude and frequency. Slowly shift the phase of one with respect to the other and add the waves, you will get a wave that beats at the frequency of the phase shift.

Al

I think one assumed that he would be sensing them with some sort of detector, but its such a vague question, if you look at 2 such waves on an oscilloscope you can see them beating as such, although to extract the beat frequency itself you do need a non linear detector.

Colin =^.^=

Leon

with

is

I'm sure I read somewhere about Sodium vapour street lights (UK), having a couple of spectral emission lines that could mix down into microwave frequencies, via the non linear gas plasma. john

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I understand the concept. It's trivial high scool stuff. What I am after is doing it with electronics.

Giorgis

Al wrote:

If you linearly add the two waves, nothing will happen. If you multiply the two waves, or add then in a nonlinear media, sum and difference frequencies may results.

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
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Please visit my GURU\'s LAIR web site at http://www.tinaja.com

Google "heterodyne". I do something similar to what you mention in generating a musical sound. My magnetic fields mix in the air with two oscillator coils in proximity to one another. A diode RC combo detects the amplitude modulation created. Here is a link to my homemade circuit board webpage using the heterodyne principle.

• * * Christopher

Temecula CA.USA

Coudl you explain what you mean by linearly add two waves or Multiply or add them in a nonlinear media ?

Regards Giorgis

Unless your air is very strange, very little "mixing" takes place in the air.

The "mixing" is directly caused by the diode nonlinearity.

--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml   email: don@tinaja.com

Please visit my GURU\'s LAIR web site at http://www.tinaja.com

Follows from fundamental trig identities.

Especially sin(u) + sin(v) = sin(u) + sin(v) with no change in a linear system

But

sin(u)sin(v) = 1/2 [cos (u-v) - cos (u+v) ] with sum and difference frequencies resulting from a multiplication or a nonlinear system.

True 4 quadrant multiplication can give near 100% conversion. Nonlinear systems will typically convert a lot less.

Unless at least one of the waveforms gets squashed, there will be no mixing and no cross products.

--
Many thanks,

Don Lancaster                          voice phone: (928)428-4073
Synergetics   3860 West First Street   Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml   email: don@tinaja.com

Please visit my GURU\'s LAIR web site at http://www.tinaja.com

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In water, if you transmit two carriers, simultaneously, where either
(or both) of their amplitudes compresses the water to the point
where it goes nonlinear, you\'ll get heterodynes.

In air, the point of compression where nonlinearity will allow that
to happen approaches the vanishing point.