Loop Antenna Crystal Radio

Discussion in 'Wireless & RF Design' started by vu2nan, Nov 25, 2015.

  1. vu2nan

    Thread Starter Member

    Sep 11, 2014
    A loop antenna crystal radio is of interest, on account of its portability, though it is no match for a crystal radio using an external vertical wire antenna and earth.

    If it's performance could be considerably improved with increased loop size, then its portability would be the first casualty.

    As usual, 2 configurations are possible - parallel-tuned-series-fed and series-tuned-shunt-fed.

    1. Parallel-tuned-series-fed version

    Parallel-tuned-series-fed Loop Antenna Crystal Radio

    2. Series-tuned-shunt-fed version

    Series-tuned-shunt-fed Loop Antenna Crystal Radio

    The loop antenna was rigged up using a 4-legged stool as a makeshift frame. The stool was laid on its side on the table, making it convenient to wind the loop on its legs.

    The 4-legged stool used as a makeshift Loop Antenna frame

    Both the versions were tested with the plane of the loop oriented towards the local 612 kHz, 200 kW AM broadcast station.

    Performance was identical though a far cry from that of another crystal radio using a vertical wire antenna and earth.



    Last edited: Aug 11, 2016
  2. KL7AJ

    Senior Member

    Nov 4, 2008
    The loop antenna is vastly superior, though, if you cannot obtain a decent ground....such as the case in Alaska!
  3. nsaspook

    AAC Fanatic!

    Aug 27, 2009
  4. KL7AJ

    Senior Member

    Nov 4, 2008
    That's really neat. The ARRL Antenna book shows an array of untuned active loops too. I imagine y0u could combine these all into a Butler Matrix and get instantaneous steering.