Is it possible to take a picture of the radio-waves on earth?

  • #1
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I was wondering If anyone knows if this is possible, or why it might be a silly idea.
 

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  • #2
sophiecentaur
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Hi and welcome
Could you be a bit more specific with your question? Radio waves are, of course, not visible but did you want to produce a 'picture' of their paths over the surface?
 
  • #3
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Yes I want to produce an image of their paths over the earth's surface. I was thinking this might be possible using the same techniques that are used in radio astronomy maybe.
 
  • #4
sophiecentaur
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Radioastronomy achieves a different thing from what you require. A radio telescope forms an image of a radio source by looking at the way the received signal level varies with angle - same as an optical telescope but with much less resolution. There is no way of showing the actual paths of radio signals directly but they can be calculated, using data about the transmission medium.
If you want to find out the path of radio waves around the Earth then you could look at the results of a Google search on Ionospheric Ray tracing - which is a theoretical method for predicting the propagation of radio waves under various ionospheric conditions. (See this link as a start)
 
  • #5
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Actually I think that I probably do want the same thing that Radioastronomy does. I am not not as interested in accurately showing their paths but just to show what the radio spectrum would look like if we had eyes capable of detecting it in a qualitative manner. Ideally I would try to detect the intensity and or frequency for a set number of pixels then map the frequencies and intensities to the visible spectrum.
 
  • #6
russ_watters
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So if you want a picture WITH radio waves and not OF radio waves, then you are talking about RADAR. That's what it is.
 
  • #7
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So if you want a picture WITH radio waves and not OF radio waves, then you are talking about RADAR. That's what it is.
If I'm correct radar takes pictures of objects be sending out radio waves and then detecting them again. What I want to do is detect the signals from radio stations or other sources that are already present. This would have little relation to the actual objects nearby.
 
  • #8
russ_watters
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If I'm correct radar takes pictures of objects be sending out radio waves and then detecting them again. What I want to do is detect the signals from radio stations or other sources that are already present. This would have little relation to the actual objects nearby.
That's still a radar picture, it would just be essentially white noise like when a TV shows static.
 
  • #9
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If I'm correct radar takes pictures of objects be sending out radio waves and then detecting them again. What I want to do is detect the signals from radio stations or other sources that are already present. This would have little relation to the actual objects nearby.
This is called passive radar. As there are typically a few dominant sources (the active radars), I don't think pictures would be interesting.
 
  • #11
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Imaging may be boring, but listening is not:

http://www-pw.physics.uiowa.edu/mcgreevy/
Yeah! Listening is pretty cool. Do you still think it would be boring if you tried look for example a city from a viewpoint and tried to see the radio stations signal propagating through. I'm worried that it would be very difficult to get the type of resolution available in images from visible light. Is that true?
 
  • #12
ZapperZ
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This is still an extremely vague question and request. What are you taking a "picture" of?

Radio waves consists of oscillating E and B fields. What exactly are you trying to map? I can easily detect the signals and amplitude of radio waves E-field by sticking in an antenna where ever there are such waves. Is this what you are trying to detect (please don't use the phrase "take a picture")?

Zz.
 
  • #13
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This is what I want to do:
Take an antenna and point it in a direction. Record the magnitude and the frequency of the radio detected. Then point the antenna in a slightly different direction and detect the same things. Do this until you have a 2d grid of these data points. Turn these grid points into an image by the proper mappings. Alternatively, you could use an array of antennas maybe but that might be impractical.
 
  • #14
Drakkith
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This is what I want to do:
Take an antenna and point it in a direction. Record the magnitude and the frequency of the radio detected. Then point the antenna in a slightly different direction and detect the same things. Do this until you have a 2d grid of these data points. Turn these grid points into an image by the proper mappings. Alternatively, you could use an array of antennas maybe but that might be impractical.
Sure, just get the equipment and it's easily possible. Though you may have problems getting up high enough to get a decent image.
 
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  • #15
davenn
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doing that only tells you what radio signal is arriving at the point of the antenna

it tells you nothing of what is happening to the signal between the transmitter and the receiving antenna
other than the signal is weak or strong

Dave
 

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