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  1. #1
    Crazy Kitty (male)
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    Custom transmitters?

    Well, this one is going to take some explaining to not sound too wierd. For a end of the year final physics project I was thinking of something nondestructive that would have a tangible result that people could seen. I was thinking of making a HERF ***, a High-Energy Radio Frequency transmitter. It would function by putting out high wattage radio noise that would disable electronics without peermanently damaging them, ex: computers would freeze but would just need to be rebooted. My experiment will be designed to test the effects of changes in distance and strength due to changes in frequency and amperage. This is where my problems begin.

    Since this place has an unusual plethora of people who are good at electronics, science, and other nonbiking things residing in these foo forums, I decided to listen to my bikeforum-using-friend and post it here. First, I would need a very powerful antenna capable of handling kilowatts, but the strongest one I could find for an everyday end user like myself is rated at 5kW. I thought about the possibility of making my own using heavy gauge copper wire in coils, but I wouldn't know how I could go about that, or if it would even be worth it if there a suitable antenna I don't know of capable of handling around 20kW. And then how to test what frequencies the antenna would be able to broadcast, with a peak of ghz as a goal. Next, what would I use to generate the frequencies and feed the result into the antenna that could handle such high wattage.

    Setup would be something like: Car Battery -> Transformer -> Circuit -> Antenna (with Horn)

    Anyone here do something like this before or can point me in a useful direction?

  2. #2
    The quieter you become... Falkon's Avatar
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    Look into making a microwave style parabolic dish. I'd say a frequency of 1.2 GHz should do you, but I have never built a HERF ***. I can say that it will NOT be cheap to get the thing to 5 KW. You parabolic dish will have gain [though I'm not sure how much] and that should allow you to run about 1000 watts in and have an effective radiated strength of 8000 watts. This is just assuming 12db gain. You need to get a high quality coax like heliax. You'll also most likely need an amplifier. It will not be cheap.
    Quote Originally Posted by TechKnowGN
    San Jose has to be the most boring place I've ever been. And I live in Ohio.

  3. #3
    Crazy Kitty (male)
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    Quote Originally Posted by Falkon
    Look into making a microwave style parabolic dish. You need to get a high quality coax like heliax. You'll also most likely need an amplifier.
    I'll start on those then, any favorite types of amplifiers by chance?

    Quote Originally Posted by Falkon
    It will not be cheap.
    Since when is anything interesting and fun ever cheap (or easy) as well?

  4. #4
    The quieter you become... Falkon's Avatar
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    ...okay then

    I don't know. I'd actually shoot for a higher frequency. I saw dishes for 3.5 GHz and I KNOW 10 GHz is pretty popular.
    Quote Originally Posted by TechKnowGN
    San Jose has to be the most boring place I've ever been. And I live in Ohio.

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