How To Look For & Find 5G Interference in C Band

[el bandido]

Microwave towers for the phone company gave the c band satellite dishes interference problems 40-50 years ago. Ironic to see these same microwave towers being used today to create interference again on c band satellite dishes.


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[el bandido]

Outlandish solutions have been proposed to fix 5G c band interference. Anything that has to do with tin foil will probably not work unless it is being used as a RF fence. Wrapping or covering a lnb in tinfoil or wrapping the scalar ring in tin foil, or even wrapping the coax in tin foil is not going to help. The reason for this is simple: The interference is the signal on the satellite dish and not on the lnb. Great if any of these tin foil solutions work for you, but shielding a c band lnb that is inside an aluminum housing makes no sense when you think about it.

[Fearless]

I've seen pictures of those "Foil solutions". Good for a chuckle or two. But seriously I use 3M aluminum tape for additional protection from RF interference. The reason they use 10 bolts to hold a LNB to a feedhorn is to prevent RF leakage. Radars are good at causing interference. Band Pass Filters have been around for a long time.

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[ArloG]

Wow. Probably repeating what's already scattered around in this thread.
Filters block a portion of the local oscillator frequency band where the low noise amplifier section of the lnbf is downconverted from the 3.7-4.2 GHz c band to 1450-950 MHz fed to the coax.
So what interference is there at the feed is amplified along with the satellite signal. The internal electronics of the lnbf are wreaking havoc from being flooded with the interfering freqs.

Now. If I'm under the correct assumption. An lnbf with built-in filtering is going to handle that task at the low noise amplifier. Or before the mixer/frequency conversion and spit out as the L.O., l band your coax sends to the receiver. A much better approach.

With any connector or splice in a run of RF transmission line. You will have an insertion loss. RG type is about the worst. But don't get confused thinking that the signal on your receiver after inserting filters, extra splices. If it happens to display 2 dB less than it did before the change. It is not that the dish electronics or your satellite signal received at the dish is attenuated.
Your local oscillator frequency signal strength has been reduced. And receivers should do a pretty good job at managing the signal. You have seen the AGC bar in your signal meter.
There will be a threshold where the coax signal will cause the receiver to fall off and drop out. Butagain. The satellite signal entering the lnbf throat is exactly the same.

Now. If long runs of coax are needed. You want the least loss/ft that you can afford. And that's where fat coax and big connectors comes in.
Many may not remember the lna and separate downconverter days. The very short connection from the lna to the downconverter box was with N Tyoe connectors. And if a cable was used to connect them. It was microwave cable. But what came out of the box to your house. Or headend. Was the local oscillator frequency. In the pressurized waveguide days the downconverter had an output signal level pot.
Because if the connection was 20 feet away from the dish electronics. You didn't want to plow a signal to the receiver that would saturate its front end electronics.

In a fixed or limited arc satellite system. Determining the direction and source of interference may be helpful. Some of us have experimented with different ways of doing just that.
If your scalar is fixed on the dish. You may even be over illuminating it by it being a touch too far out. I don't trust strut bar mounted scalars that are stabbed where the arms bolt to them.
Anyway. You can accept interference. Buy filters and craigslist or eBay them if they don't work (vendors aren't liking try-and-return). Buy properly filtered lnbf. The best way. If in fact the filtering isn't hidden inside right before the coax connection.

Drive around. Look on towers for microwave antennas. Most may have a radome over them. Yeah, to keep birds and bird crap off of them. But look closer. The have a rim extension. And that rim extension has a layer of impregnated radar absorbing material. RAM. Stealth aircraft stuff.
Its there to not only reject off axis microwave interference. But to absorb side lobe interference. Who knows. A wrap of aluminum flashing or stiff screening and grounding it good around your dish rim may do wonders. Maybe some crafty guys here with 5g interference and know the direction it comes from could try that. Can't hurt, right!
Oh. Also. I don't know so much about aluminum tape and foil around your lnb or waveguide joints. If that were the case. Those little tiny holes on your microwave oven door window would have you with boiled eggs for eyeballs in a jif. Do the math. The wavelength for the frequency. Divide that by 1/4, 1/2, 5/8. If you have a gap that big. Better shop for another piece of hardware.

I'm thinking that if this 5g thread keeps going on. Until something remarkable comes out to cure the issue. It's kind of a no brainer. The stuff here is just crap I know.