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g86
Joined: 21 Jan 2003
Posts: 208
Helped: 4
Location: On top of antenna :))
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 15 Mar 2003 0:25 Microwave Camera |
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I am going to make a microwave camera. just like optical one. no tracing or tracking. Microwave pinhole camera. Who can help me to select:
1. A box
2. Pin Hole
3. Photographic plate
4. Focusing lense
First of all I want to know what will be my output picture??
Who can help...
  
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
Location: Middle Earth
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| 15 Mar 2003 4:35 two aspects |
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There are two aspects to this problem. Both involve the 1E4 to 1E5 ratio of the wavelengths.
The physical size should be scaled from a working optical pinhole camera by the above factors. This would reduce the portability.
The other problem is the reduction of a photon energy by the same factor. This is the show stopper (no solution). Finding a detection scheme which would work on such low photon energy is a problem. This is way below the chemical bond energy of photo film and the band gap of semiconductor detectors.
What about using a two dimensional phased array and ordinary microwave amplifier/detector/video amplifier? You could raster scan vertical and horizontal angles and use the detected energy to intensity modulate a display of the television or computer monitor type.
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g86
Joined: 21 Jan 2003
Posts: 208
Helped: 4
Location: On top of antenna :))
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| 15 Mar 2003 13:58 Re: two aspects |
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| flatulent wrote: |
What about using a two dimensional phased array and ordinary microwave amplifier/detector/video amplifier? You could raster scan vertical and horizontal angles and use the detected energy to intensity modulate a display of the television or computer monitor type. |
Just like CCD camera..right?
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
Location: Middle Earth
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| 15 Mar 2003 17:47 not exactly |
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This is not exactly like a CCD. In that method the light image falls on many locations on the semiconductor and produces photons. In this method all of the antenna elements receive signals and combine them into one amplifier path.
This is sort of like a RADAR set only there is no transmitter. The receiver depends on active emitters. Another way of looking at it is a direction finding system with the parameters horizontal and vertical angle.
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g86
Joined: 21 Jan 2003
Posts: 208
Helped: 4
Location: On top of antenna :))
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| 15 Mar 2003 18:16 Re: not exactly |
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Then how to make an image. This is just like a single antenna and without scanning how will it work?
| flatulent wrote: |
This is not exactly like a CCD. In that method the light image falls on many locations on the semiconductor and produces photons. In this method all of the antenna elements receive signals and combine them into one amplifier path.
This is sort of like a RADAR set only there is no transmitter. The receiver depends on active emitters. Another way of looking at it is a direction finding system with the parameters horizontal and vertical angle. |
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tschang06
Joined: 22 Feb 2003
Posts: 3
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| 15 Mar 2003 19:04 |
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
Location: Middle Earth
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| 15 Mar 2003 21:58 set of numbers |
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You will get a set of voltages for each vertical and horizontal angle that you scan the antenna. These will have to be turned into visual pixels by electronic display means.
Because of the very large wavelength, you will get very crude images due to the wide beamwidth of any portable sized antenna.
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crono
Joined: 01 May 2001
Posts: 59
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| 16 Mar 2003 10:19 |
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Hi,
If i'm not wrong you are talking about a radiotelescope...
In relation with the beam size of the antenna, wich resolution do you want?
and for wich kind of images?
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g86
Joined: 21 Jan 2003
Posts: 208
Helped: 4
Location: On top of antenna :))
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| 16 Mar 2003 17:29 |
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Now it is difficult to answer your question because I don't know much about the priciple of working of a radio telescope. I just thought about a pin hole camera.
Now as you know if we want to replace with a microwave camera we have to go for a big pin hole as well as big cavity, though they are dependent on wavelength. Another thing is that we cannot use a camical to take the image. we have to use antenna for receive the image. Flatulent has suggested some way of getting the image by cluster of antenna and sensing the active radiation. I feel we also can use a transmitter antenna which can be use like a flash 
What do you think? After design and fabrication surely I ll install it at moon as my next project..and focus it on earth..to see the radiating earth and reflector earth..
| crono wrote: |
Hi,
If i'm not wrong you are talking about a radiotelescope...
In relation with the beam size of the antenna, wich resolution do you want?
and for wich kind of images? |
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