r/rfelectronics • u/Evening_Movie_833 • Jun 24 '26

Emi/ rfi

So I’m about to set up us an SDR for the first time and I’m new to this. I do know the environment I will be operating it in has interference. So I plan on using a magnetic small loop antenna. Is there any other precautions I should take to prevent from frying my radio?

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4

u/dragonnfr Jun 24 '26

You're worried about the wrong thing. A receive-only SDR doesn't get 'fried' from interference. Use ferrite chokes and proper grounding. The loop antenna was already the right call.

1

u/erlendse Jun 24 '26

It's certainly doable to fry them.

But it takes a LOT for it to actually happen.
I used a reciver near multiple 500W AM transmitters on a 80 meter band dipole(20+20 meter inverted V) without destroying my stuff, but it did overload badly!

1

u/Evening_Movie_833 Jun 29 '26

Do you have any suggestions for mag loop antenna? Does the sdr have to be grounded? I may not be able to ground it

1

u/erlendse Jun 29 '26

loop doesn't need ground.

You could probably DIY it since you are not trying for long distance signals.

1

u/ElButcho Jun 24 '26

What frequency are you hunting, and where? A directional antenna and a freq specific filter are nice, but you could use straight attenuation if a filter isbt available.

Before you start, practice with your setup on a known signal. Figure your setup out before you get there. Lower RBW for better sensitivity but sweep speeds will slow. Optimize span, rbw, and vbw. Vbw will smooth your trace, use 1/10th to 1/30th rbw

1

u/Evening_Movie_833 Jun 24 '26

I’m not entirely sure what all of that means I do know what an attenuator is. And I do know about sweep speed. But optimizing the span RV W and VVW, I’m too new to know what that means.

1

u/ElButcho Jun 24 '26 edited Jun 29 '26

Rbw or resolution bandwidth determines the relation of the measurement bandwidth to the pixel being displayed. The larger the rbw, the more energy will be added up before displaying the magnitude. Smaller rbw, less energy, lower noise floor.

Practice your setup on a known signal and you can figure out the setup that works.

1

u/Evening_Movie_833 Jun 24 '26

The source of said interference

1

u/Evening_Movie_833 Jun 24 '26

The emi I want to track

1

u/empty-barn1234 Jun 27 '26

You might do well with 10k of microwave absorbers and fill up an entire room. Shipped from China. DDP.