At what frequency(ish) does a small receiving loop lose directivity?


Kev Haworth
 

LAA+ now running a 1.2m loop from 10mm refrigeration pipe.

One big difference is that I'm having to reduce the RF Gain on SDRUno far more than with the Kunifer pipe, which I presume means the Refrigeration pipe is driving the amp with more gusto..

What sort of frequency does a loop with this configuration stop exhibiting directivity?

ODX since implementing this recent change are NDB in Croatia, 360Khz ish, 15m sw several YB (Indonesia) stations and plenty of west coast stations on 17m.


Chris Moulding
 

Looking at your example of a 1.2m loop it will have a full wave resonance like a quad loop at 79.6 MHz.

On that frequency the maximum gain will be broadside to the loop..

At low frequencies where the loop is a small fraction of a wavelength the sharp nulls are broadside to the loop.

You will probably see the loop lose it's directivity as it changes from one mode of operation to the other around 25 - 30 MHz..

Regards,

Chris