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Loop antennas

Discussion in 'Electronic Basics' started by Roger Dewhurst, Jan 25, 2006.

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  1. Assuming that a single turn loop will receive a particular frequency better
    than others will a multiple turn loop of the same diameter receive the same
    frequency rather better?

    R
     
  2. The best performance will then be at a lower frequency (in general).
     
  3. How does the frequency change with increasing number of turns? Is there a
    rule?

    R
     
  4. Too many factors. At the very least, the resonant frequency must drop
    inversely proportional to the total wire length in the loop. So
    doubling the turns on the sane size loop must at least halve the
    resonant frequency.

    But this is a limit.

    Assuming almost all the flux that passes through one turn also passes
    through all the others, the inductance will rise almost proportional
    to the square of the number of turns. The inter winding capacitance
    and other stray capacitance also rises as the turns rise. These two
    factors also lower the resonant frequency.
     
  5. Phil Allison

    Phil Allison Guest

    "Roger Dewhurst"

    ** Multi turn loop antennas (or " frame antennas" ) are commonly used on AM
    band receivers.

    In this case, a loop of convenient size can be made to resonate within the
    band of interest with a small fixed or variable capacitance in parallel.

    Works well for local broadcast reception.



    ......... Phil
     
  6. Jasen Betts

    Jasen Betts Guest

    no. the multiturn loop will will receive the same frequency but with a
    higher impedance (more voltage less current -> same power).

    If you wany more signal strength, you need multiple loops, or other
    strategically placed bits... look up "phase array" and "yagi antenna"
    for two examples.

    Bye.
    Jasen
     
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