Re: New style FSL Part 2


The idea of using two separate loops to produce phase cancellation can be applied to either QRM, QRN, and/or unwanted medium wave signals.

Two signals of equal amplitude and 180 degrees out of phase with reference to each other will cancel. This can be easily demonstrated mathematically, or even with a CRO. In the real world, especially with varying evening amplitude from E layer skywave signals, the phase relationships do not usually correspond to a perfect null. Nevertheless, useful signal nulls can still be obtained.

I can use my home-constructed 40 inch side length PVC box loop in conjunction with a 25.6 inch (65 cm) diameter PK circular loop for nulling QRM, QRN, or unwanted MW signals. The large 40 inch loop is the DX antenna, while the smaller 25.6 inch loop is the noise pickup antenna. Both antennas introduce phasing via inductive coupling.

The late Joseph J. Carr wrote a paper detailing the advantages of using two loops to introduce phase cancellation [1].


Sydney, AU


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