RF Energy Recovery

Discussion in 'The Projects Forum' started by wwchieh, Oct 19, 2009.

  1. wwchieh

    Thread Starter Member

    Apr 25, 2009
    I am picking a final project for an analog circuit course. I am interested in RF Energy Recovery, which is recover energy from ambient wireless signaling.

    Anyone with experience/ knowledge, please give some advice on this subject to me. Even better recommend books/articles that are useful.

    Thank you very much.

    Senior Member

    May 26, 2009
    You're not going to get much recovery power from RF sources. Have you ever heard of a crystal radio? Well these radios don't need a power source to receive. You see, the radio stations send out thousands of watts of power and by the time it gets to your location it would probaby be near a couple μW or nW. But that's all you need to make it work, they have a very sensitive ceramic earphone whereas a speaker would need an amplifier to drive it.

    So the point is, you're not going to recover much RF power from nearby sources maybe a couple μW or nW; that's all. Thus, why would you spend time on doing something like that when you could get more energy from solar panels or wind energy?

    Another idea you might consider is a viabrational generator. The military developed this small device that would recover the viabrational energy when soldiers were walking. Note that you would have to rectify the source in order to get anything out of it. But the soldiers were able to charge a battery back. You'd get more energy out of that then your idea.
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    Ambient wireless signalling covers a huge area. Can you narrow it down? The closest thing that springs to mind is RFID, where the tag is powered by the reader's signal.
  4. wwchieh

    Thread Starter Member

    Apr 25, 2009
    It is one of the suggested projects from my professor.
    Below is what he wrote. I haven't really talked to him yet.

    4) RF energy recovery.
    Build a circuit to recovery energy from ambient wireless
    signaling (UHF TV signals or cell phone handset or base signals)
    This is hard to do, but very useful if you can make it work.

    Thanks for everything.
  5. Wendy


    Mar 24, 2008
    Now if you lived next to a megawatt AM radio station it would be a piece of cake.

    You almost have to match a job to this, with so little power you have to have an application that doesn't need much.

    I'm not sure if it falls under the same catagory, but it is possible to remodulate an RF signal with new information. In other words, recycle an existing signal for a new application.