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.

[el bandido]

The best days for c band satellite are over for me. 5G c band has took over my c band dish.

Where is the interfering signal?
Interference started about the first of June and got worse over the period of one week. The signal analyzers were connected to the c band lnb and cellular c band signals were noticed. A combination of walking and driving pointed the signal source to a cell tower roughly 1 kilometer or about half a mile point to point or air distance. No other interference sources besides the cell tower have been found.

How strong is the interference?
The signal analyzers I am using are cheap, non-professional types. These analyzers show an average signal around 20db above the noise floor with peaks at times going to 40-60db above the noise floor.

What can be done to lessen or lose the interference?
Probably Nothing. The handheld analyzer shows some decrease in cell signal strength at some places where the dish could be moved, but the cell signal never disappears completely. The satellite dish is located in the downtilt area of the cell tower, which makes the cell signal arrive at a similar angle as the satellite signals.

Temporary Solution:
Purchase one 4.0-4.2 MHz filter as a test.

People that are putting up new c band dish antennas need to be aware of this cellular c band stuff. A filter will probably cost me roughly 2 db in signal loss. This will make my 12 foot dish perform like a ten footer. My 7.5 foot dish would perform about like a 6 footer with filters installed. Not to mention that I also lost roughly 600Mhz of usable c band satellite frequencies. None of this is good....

[eastof111]

Bummer.... 5G is truly an itch you can't scratch. Prior to the program providers moving to different sats and higher frequencies, I had pretty bad 5G problems on certain sats. My concern was that I would have to replace very, very old c/ku lnbf with newer Norsats and filters.

Luckily, reception improved after the frequency and sat relocation. Occasionally I will get some interference, but it disappears after an hour or so. But, I have a cell tower 1/2 a mile away and the other one is located about four blocks away.

I guess I can live with the occasional interference until the 5G providers hopefully clean up their act. Hope your situation improves in the future.

[el bandido]

My particular problem is the cell tower is about a kilometer almost due south, and has a height advantage of at least 100 meters.. I am being smothered in a blanket of 5G C band signals that are hitting the dish directly. The interference is equal pretty much in any direction the dish can move.

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[skink]

I know of someone who was experiencing 5G interference that made a vast majority of channels unwatchable or totally gone.I took a chance and bought a Titanium Red feedhorn and now I don't hear anymore complaint.I don't know if this would help in your situation or not?Definitely a real bummer!

[el bandido]

I appreciate the information about the Titanium Red product, but that lnb will not cover where my 5g C band is operating. Right now, i am having problems in the 3980-3990 MHz range. These frequencies are beyond the coverage of the Titanium Red piece.

Prices for 5G bandpass filters are dropping. The Eagle red filters are already 100 dollars less than their Blue filter. would not be suprised to see bandpass filters in the hundred dollar range in a year or two.

The C band satellite hobby gets expensive once 5G is properly introduced to your dish. A pair of bandpass filters can easily run $600.00 while a proper 4.0-4.2 GHz (4000-4200 MHz) lnb from Norsat will be around $700.00 Minimum, or roughly $1400.00 for a pair.

$200-$300 U.S. Dollars used to go a long way in the satellite hobby. But that amount is a drop in the bucket when you have 5G cell signals hitting your dish directly.

Here are a couple of analyzer screenshots of 101w showing the problem I have with 5G in the 3980-3990 frequency range:
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This screenshot shows the whole spectrum the lnb is capable of on 101w:
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My only salvation is when the 5G showed up, it was easy to see that it was not gonna be easy to beat.

[el bandido]

It is easy to get confused about the air distance between your dish and the 5G C band signal source. If the offending 5G tower is visible, you might look at it and decide how far away it is. But to figure out what you need to do, or to understand how the 5G C band signals may be hitting your dish, the correct distance and the height of the C band interference needs to be known.

There are websites that list tower height, and some may also list average height above terrain as HAAT(Height Above Average Terrain). The Air distance to the the interference source, and how high it is above your satellite dish will help piece together how the signal is hitting your satellite dish. In my particular situation, I am in a "blanket" area where the 5G cell signals are dropping straight down on the dish. I am close enough to the tower to get this blanket effect, but I am also a bit further away from maximum signal, which means the 5G signals are not near as strong as they could be.

I find dishpointer.com to be useful for finding air distance between the 5G tower and satellite dish. The dispointer map draws a line, so I simply find my dish location and mark it, then find the tower and use a satellite from the list to put a line over or near it. Now I can measure the line between the satellite dish and 5G tower, then reference the same distance to a road or something else where the distance is known and get a good idea of the actual distance in the air between the 5G C band tower and the satellite dish. There may be better sites for doing this, but dishpointer.com worked very well for me.

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