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Rectenna

Discussion in 'General Electronics' started by Ed Neipris, Jun 28, 2005.

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  1. Ed Neipris

    Ed Neipris Guest

    Hello,
    I'm trying to demonstrate the effects of Wireless Power Transmission
    (WPT), but, I must be doing something wrong (or expecting the wrong
    results). I'm using an NTE586, as a Schotkky Diode, I attach an LED across
    the leads, and then hold it behind a 600 watt microwave. I don't see any
    change on the led. A simple voltage read shows no DC Voltage. When I hold
    the apparatus near an active cell phone, I read .2-1.2 millivolts. I've also
    held the diode infront of a 802.11b Transmitter, Chatting at 32dBi and saw
    no change on a voltmeter (00.0mv) If anyone has experience with this could
    you please point me in the right direction. Am I using the wrong Schotkky,
    am I expecting too much out of WPT, really all I want to see is the LED
    light up, or some type of meter change.

    Thanks for your time.
    Ed......
     
  2. CWatters

    CWatters Guest

  3. Charles Jean

    Charles Jean Guest

    ___
    You'd probably need a better antenna to catch it in. Microwaves are
    pretty well directed and tend not to be dispersed. Plus your
    microwave oven should not be leaking any microwaves anyway. I'm also
    wondering if the diode you are using might be losing efficiency at
    microwave frequencies.
    I just finished a project along these lines, but concentrating on the
    RF range. The reference I used was:
    http://www.rexresearch.com/tate/tate.htm#apm
    Evidently, the name of the game is to extract as much RF energy you
    can from existing RF field, losing as little as possible in the
    process. The circuit uses four diodes in a voltage quadrupler
    configuration. I checked several types of Shottky and germanium
    diodes, and the 1N34A germaniums seemed to have the lowest, match able
    forward voltages.
    I used 100 uFd electrolytics and .01 uFd caps, neither of which
    seemed to be critical values. I used a 100' 24ga insulated wire L
    shaped antenna draped over a 6' backyard fence and a copper cold water
    pipe as a ground.
    I made a data logger from a PIC16F877A to log the readings to a PC via
    the RS232 port into a PC text file, and then imported the text file
    into Excel for graphing. The logger is set to log a data point every
    minute. I got about 10 day's worth of data for the outside antenna
    and just got a dipole antenna(see attachments) set up to start logging
    yesterday.
    Incredibly, the inside dipole antenna beat the outside antenna! With
    either one, you can see a pronounced daily step in voltage right at
    sunrise and sunset. I attribute this to an AM station about 2 miles
    from my house that is one of those that go from 1000 watts at night to
    50000 watts in the daytime.
    I'm sure if you use something like this you'll definitely see some
    measurable voltage readings. I wouldn't stop the research on fusion
    just yet though(hot or cold). Tate mentions that his rig will power a
    digital clock that uses 1.5 volts at 28 uamps, or 42 uwatts. If your
    LED requires a forward voltage of 2.5 volts at 10 ma., that's 25
    milliwatts, or 25000 uwatts! I wonder if it could even keep an AA
    NiMH cell trickle charged? How much power did you want to
    transmit/receive wirelessly?

    P.S. Please excuse the length of the PNG file. I've been having
    trouble with my file conversion utility lately and it's the best I
    could do under the circumstances.

    Charlie
     
  4. Charles Jean

    Charles Jean Guest

    ___
    You'd probably need a better antenna to catch it in. Microwaves are
    pretty well directed and tend not to be dispersed. Plus your
    microwave oven should not be leaking any microwaves anyway. I'm also
    wondering if the diode you are using might be losing efficiency at
    microwave frequencies.
    I just finished a project along these lines, but concentrating on the
    RF range. The reference I used was:
    http://www.rexresearch.com/tate/tate.htm#apm
    Evidently, the name of the game is to extract as much RF energy you
    can from existing RF field, losing as little as possible in the
    process. The circuit uses four diodes in a voltage quadrupler
    configuration. I checked several types of Shottky and germanium
    diodes, and the 1N34A germaniums seemed to have the lowest, match able
    forward voltages.
    I used 100 uFd electrolytics and .01 uFd caps, neither of which
    seemed to be critical values. I used a 100' 24ga insulated wire L
    shaped antenna draped over a 6' backyard fence and a copper cold water
    pipe as a ground.
    I made a data logger from a PIC16F877A to log the readings to a PC via
    the RS232 port into a PC text file, and then imported the text file
    into Excel for graphing. The logger is set to log a data point every
    minute. I got about 10 day's worth of data for the outside antenna
    and just got a dipole antenna(see attachments) set up to start logging
    yesterday.
    Incredibly, the inside dipole antenna beat the outside antenna! With
    either one, you can see a pronounced daily step in voltage right at
    sunrise and sunset. I attribute this to an AM station about 2 miles
    from my house that is one of those that go from 1000 watts at night to
    50000 watts in the daytime.
    I'm sure if you use something like this you'll definitely see some
    measurable voltage readings. I wouldn't stop the research on fusion
    just yet though(hot or cold). Tate mentions that his rig will power a
    digital clock that uses 1.5 volts at 28 uamps, or 42 uwatts. If your
    LED requires a forward voltage of 2.5 volts at 10 ma., that's 25
    milliwatts, or 25000 uwatts! I wonder if it could even keep an AA
    NiMH cell trickle charged? How much power did you want to
    transmit/receive wirelessly?

    P.S. Please excuse the length of the PNG file. I've been having
    trouble with my file conversion utility lately and it's the best I
    could do under the circumstances.

    Charlie
    ___
    Sorry, forgot the PNG file. Here it is in all its hugeness.
     
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