Radio Frequency Imaging

Discussion in 'General Electronics Chat' started by Dave, Apr 14, 2006.

  1. Dave

    Thread Starter Retired Moderator

    Nov 17, 2003
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    For some time I have been working in the field of medical imaging and reconstruction, particularly the field of Electrical Impedance Tomography (EIT) with applications to the brain. Now I want to look a little deeper at radio frequency (RF)imaging, and what are RF imaging opportunities, market niches if you will, that are available for wider industry (not just medical applications). I am required to write a presentation on this subject in the coming week or so.

    Having spent several hours this morning trawling the Internet and reading chapter after chapter of Kempes, I am a little at a loss as to finding information about RF imaging.

    Does anyone know of any good RF imaging websites or books that would provide a good general overview of RF imaging techniques and applications of RF imaging - any website or book, no matter how trivial, is welcome. I am obviously familiar with concepts such as MRI and the opportunities for this with regards to medical applications, but would like some more general information. I also welcome comments from those working in the RF imaging community.

    Any information would be appreciated.

    Dave
     
  2. Papabravo

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    Feb 24, 2006
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    One of the things you might be interested in is called Synthetic Aperture Radar(SAR). The original work was done at the University of Michigan in the 1950's and 1960's. Googling the term produces about 18,600 hits.

    The false color images from the radar return are truly surreal. You can even tell where the airplane is flying by the location and orientation of the microwave shadows. What's a micrwave shadow? It's a place on the ground that absorbs the microwave energy and produces no return signal.

    Check it out.
     
  3. Dave

    Thread Starter Retired Moderator

    Nov 17, 2003
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    Thanks for the pointer Papabravo, I have come across SAR in the past - love the colours!! It suffers from the common RF imaging problem of image target mobility.

    Out of curiosity, apart from Radar Systems and medical applications, what systems commonly use RF imaging? I have done some work in biometrics, where RF imging is fairly common.

    Dave
     
  4. Papabravo

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    Feb 24, 2006
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    Dave,

    The only other application that I have any familiarity with is Radio Astronomy. Here the false color images are a function of frequency since AFAWK there are no extraterrestrial modulation sources. Well OK I guess pulsars emit periodic pulses, but tha't about it.
     
  5. Dave

    Thread Starter Retired Moderator

    Nov 17, 2003
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    Radio astronomy is something that did cross my mind, but for the purposes of what I will be doing this presentation on I think Radio Astonomy may be a bit too much of a niche market. I was thkning more about RF imaging systems for Airport Security Systems, or Food Monitoring Systems.

    Its amazing how little information I can find out there about general RF imaging techniques - maybe thats the catch with this particular subject.

    Dave
     
  6. n9352527

    AAC Fanatic!

    Oct 14, 2005
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    If I remember correctly, a friend of mine that worked on metal NDT mentioned that there was a research group that did concrete NDT using RF imaging to identify cracks and voids. I don't remember from which university, but it should not be too hard to find. I would think that concrete NDT is a quite good industrial application. There might be also an opportunity in paint QC, where they use this kind of thing to control/check the quality of paint application on numerous materials.
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
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    Hi,

    You might find that RF imaging is limited in it's medical applications. Aside from side effects (it is ionizing radiation, after all), the capability of resolving fine structures is pretty crude. If you think about it, 10 cm radar has poor resolution when compared to optical wavelengths.

    One interesting side effect from an application of SAR was an interference ring effect that drew topo lines on the reconstructed image. One could choose the contour interval by selecting the radar frequency. I saw this some years ago, and have no idea of the reporting agency.
     
  8. Dave

    Thread Starter Retired Moderator

    Nov 17, 2003
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    NDT is a major area for imaging, and is a pretty good example. I know that it is commonly employed in the aeronautical industry to test for microscope defects in the materials used. I will try and dig out some information.

    EDIT: I have found some interesting information on approaches to the use of RF imaging for real-time 'in-the-field' NDT systems, from the University of Surrey. Imaging for inspection purposes is clearly an area for development in the field of RF imaging.

    <!--QuoteBegin-beenthere
    @Apr 14 2006, 08:55 PM
    Hi,

    You might find that RF imaging is limited in it's medical applications. Aside from side effects (it is ionizing radiation, after all), the capability of resolving fine structures is pretty crude. If you think about it, 10 cm radar has poor resolution when compared to optical wavelengths.

    One interesting side effect from an application of SAR was an interference ring effect that drew topo lines on the reconstructed image. One could choose the contour interval by selecting the radar frequency. I saw this some years ago, and have no idea of the reporting agency.
    [post=16182]Quoted post[/post]​
    [/quote]

    You are right about the limitations of RF imagaing for medical applications, but it is widely used - take MRI for example. MRI has many problems of its own, and is often too slow for real-time imaging - hence my research into sub-second techniques.

    Dave
     
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