Signal improvement using a ferrite rod with a small loop antenna

[prabhatkarpe4]

I have used my small loop antenna (which has a main loop and a coupling loop that can be tuned using a variable capacitor) with an AM radio receiver to receive MW broadcasts. However, the small loop antenna which was made by me was not working properly but when I connected a ferrite rod loop (which has two windings on it---one with 60 turns and the other with 30), I saw a great improvement in radio reception. I connected the 60 turns loop with the main loop of the small loop antenna and the 30 turns loop with the AM radio.

The ferrite loop is not working as an antenna and when I turned it, I didn't get any difference in signal strength. However, when I turned the small loop antenna, I saw the change in signal.

So, I need to know why this has happened and did the ferrite rod work like a balun?

I have attached the diagram of the setup.

[T3sl4co1l]

I'm afraid, explaining why, would require RF knowledge --

https://www.eevblog.com/forum/rf-microwave/number-of-turns-for-the-coupling-loop/msg5657791/#msg5657791

Should I take that to understand, you are interested now in deepening your knowledge?

Tim

[radiolistener]

So, I need to know why this has happened and did the ferrite rod work like a balun?

in your case it works like transformer with impedance transform ratio 4:1. And yes, such transformer can be used as balun.

[prabhatkarpe4]

But howcome that's 4:1? it's have 60/30 turns and should be 2:1.

[ftg]

But howcome that's 4:1? it's have 60/30 turns and should be 2:1.

Impedance transformation ratio is the square of the turns ratio.
2^2 is 4, thus 4:1 impedance transformation ratio.

[A.Z.]

But howcome that's 4:1? it's have 60/30 turns and should be 2:1.

Impedance transformation ratio is the square of the turns ratio.
2^2 is 4, thus 4:1 impedance transformation ratio.

Yep, we have 60 and 30 turns, so the turns ratio (not the number of turns) is 2:1 which means a 4:1 impedance transformation ratio, as a note it's usually a good idea to wind the lowest reasonable amount of turns (depending from core material characteristics) to reduce losses and avoid unwanted self-resonance, an example, willing to wind a 9:1 transformer using a #73 binocular core we start by obtaining the turns ratio, that is sqrt(9), which gives us 3, at that point we wind 6 turns and 2 turns which will result in our 9:1 impedance ratio corresponding to the 3:1 turns ratio we calculated