Need help to Make Flat antenna

Discussion in 'The Projects Forum' started by Etronic, Feb 3, 2015.

  1. Etronic

    Thread Starter Active Member

    Oct 7, 2011
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    2
    Found this antenna on yahoo sometime ago can't find the site again.

    I need to know how to make this antenna.

    I need to make a 400 micro Henry antenna like the one attached.

    Using 26g stranded wire or 20g magnetic wire.Which one would be better.

    How many turns with it take to get with either type of wire at 400uH.

    Each antenna can not be more the 1.8'' wide.

    Can someone help me to calculate. And who know's about these types of flat pancake antenna.

    Also? Do the two end wires get connected as one.Or do they need to be connected in a circuit separately.Does one side of the wire go to ground.I don't know how to connect it in circuit.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    What frequency is this supposed to be for?
    Transmit or receive?
    Power level?
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    At these frequencies, these are not "antennas"; they are coupling coils, relying on magnetic coupling.

    Presumably, any given pair (one transmitting, the other receiving) will operate centered on a frequency which is known ahead of time.
    Normally, you would resonate the coupling coils (both the transmitting coil and the receiving coil) by making them part of resonant circuits. Choice of an operating frequency and modulation method will dictate the bandwidth of the resonant circuits.

    The transmit power level will be the primary determinant of how far apart the transmitter and receiver can be. The best range will be obtained when operating near 50kHz; wont work at all below about 10Khz. Even then, the range is likely to be a few cm.

    Is this for an RFID project?
     
  4. Reloadron

    Active Member

    Jan 15, 2015
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    The antenna you are describing sounds like the old AM radio antennas found on the inside cover of old AM radios. Maybe an AM receiver type tank circuit a detector and a 741 as an amplifier. I haven't a clue what the digital logic chips you mention may have done.

    Coil AM Antenna small.png

    Heck, it could have been anything.

    Ron
     
  5. Reloadron

    Active Member

    Jan 15, 2015
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    Inductance[μHenry] = [​IMG], 1

    L = inductance (µH)
    r = mean radius of coil (in)
    z = physical length of coil winding (in)
    N = number of turns
    d = depth of coil (outer radius minus inner radius) (in)

    That's the formula for Inductance. There is much, much more to everything you are talking about. There is no way to know what you previously had or how it was wired, not without a drawing anyway. All you have mentioned is a collection of digital ICs and a 741 operational amplifier. There is not enough there to go with. You mention Record? When you record you need someplace to put or store the data? Nothing there will do that.

    If you are into this sort of thing you may want to give this a read: NASA Spacecraft Records 'Earthsong'.

    Ron
     
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
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  7. Reloadron

    Active Member

    Jan 15, 2015
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    The best I can tell you is as far as being able to record and play back a Google of "Chipcorder" will bring up a line of chips that can actually record and play back audio analog signals. You have likely seen these chips used in greeting cards that you can record to. ISD (Information Storage Devices, now Nuvoton), developed the technology. As to a receiver a Google of "Crystal Radio" will bring up dozens of hits and circuits. When I was a kid I would take a 1N34 germanium diode and using only an antenna and headphones listen to a local AM radio station. Could also hear a lightening storm approaching miles away. :)

    So my best guess is if you want to detect or listen to magnetic or radio type signals out there I would imagine you could build a detector of sorts and use an ISD type chipcorder to record what you hear in headphones. I have never done it or given it any thought. There is no way I am aware of to define what the box was that you had.

    Ron
     
  8. Reloadron

    Active Member

    Jan 15, 2015
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    There is much more to it than the 400uH. The coil is set with a capacitor for a resonant circuit, like a tank circuit. That is why I suggested looking at crystal detectors to get some ideas. You would do better looking at maybe 1 to 12 KHz basic VLF (Very Low Frequency) receivers. This stuff is far from my forte, I haven't messed with stuff like this in well over 50 years. What you need is a RF type person and someone familiar with VLF stuff. Anyway in the 1 to 12 KHz bands is where you find low frequency magnetic emissions and other strange phenomenon that is interesting to listen to. I simply don't know this stuff well enough.

    Ron
     
  9. Allfather

    New Member

    Feb 11, 2015
    9
    0
    That looks like like a Tesla pancake coil.
     
  10. Allfather

    New Member

    Feb 11, 2015
    9
    0
    Good luck in your search.
     
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