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Is it possible to generate a beating wave ?

G

Giorgis

Jan 1, 1970
0
Is it possible to generate a beating electromagnetic wave ?
Were can I find some info on the topic ?

Thanks

Giorgis
 
L

Leon

Jan 1, 1970
0
Giorgis said:
Is it possible to generate a beating electromagnetic wave ?
Were can I find some info on the topic ?

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

Leon
 
G

Giorgis

Jan 1, 1970
0
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
 
E

Ed Douglas

Jan 1, 1970
0
Leon said:
Not directly, AFAIK. You could receive it with an antenna, beat it with
another signal using a mixer and retransmit it.

Leon

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.
 
C

colin

Jan 1, 1970
0
Giorgis said:
Is it possible to generate a beating electromagnetic wave ?
Were can I find some info on the topic ?

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
 
C

colin

Jan 1, 1970
0
Giorgis said:
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

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

Colin =^.^=
 
D

Don Bowey

Jan 1, 1970
0
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

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
 
D

Don Lancaster

Jan 1, 1970
0
colin said:
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

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.



--
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: [email protected]

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

Leon

Jan 1, 1970
0
Ed said:
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.

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
 
G

Giorgis

Jan 1, 1970
0
<<SNIPP>>
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
 
A

Al

Jan 1, 1970
0
Giorgis said:
<<SNIPP>>
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
 
C

colin

Jan 1, 1970
0
Leon said:
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.

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 =^.^=
 
J

john jardine

Jan 1, 1970
0
colin said:
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 =^.^=
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
 
G

Giorgis

Jan 1, 1970
0
I understand the concept. It's trivial high scool stuff. What I am
after is doing it with electronics.

Giorgis
 
D

Don Lancaster

Jan 1, 1970
0
Giorgis said:
<<SNIPP>>
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
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.


--
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: [email protected]

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

christopher

Jan 1, 1970
0
Is it possible to generate a beating electromagnetic wave ?
Were can I find some info on the topic ?

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.

http://www.oldtemecula.com/theremin/ultimate2b/index.htm



* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com
 
G

Giorgis

Jan 1, 1970
0
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.

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

Regards
Giorgis
 
D

Don Lancaster

Jan 1, 1970
0
christopher said:
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.

http://www.oldtemecula.com/theremin/ultimate2b/index.htm



* * *
Christopher

Temecula CA.USA
http://www.oldtemecula.com
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: [email protected]

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

Don Lancaster

Jan 1, 1970
0
Giorgis said:
Coudl you explain what you mean by linearly add two waves
or Multiply or add them in a nonlinear media ?

Regards
Giorgis


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: [email protected]

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

John Fields

Jan 1, 1970
0
Coudl you explain what you mean by linearly add two waves
or Multiply or add them in a nonlinear media ?

---
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.
 
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