The answer to that is that its not always an issue. In a clean air environment, with the wireless cards spread out in frequency or even spread across multiple bands, the performance is very good.
A very good question often asked, lets use 433 as a example, it could use three radio cards 900/2.4/5.8 but not 2.4/2.4/2.4 or 5.8/5.8/5.8…
There is no good trick to shielding them but a much better and more efficient method of maximizing TX radiated RF power is to use integrated sectors that have a radio compartment to place the Mikrotik board.
I have a shielded container for RB and i put it 1m away from the sectors, attached to it with two shielded coaxial cables.
So, you suggest:
1 RB => 1 Radio → When there are competitors and there isn’t clean air space
1RB => More radios => When I’m alone and there is clean air space
?
Exactly where is the noise located? I mean, the problem is the radio card, the pigtail, the sector…?
No - It’s just good installation practice for performance to use 1 RB=1 radio - for all locations and regardless of clean air space or not - many other users will advise the same, now using integrated AP or not it’s you choice but you will have more transmitted power when using integrated and not using the 1M RF loss loss LMR ,etc. cable, quoted cable loss and actual measured on site insertion loss when using RF connection lead can be in dB’s and not say 0.15dB as in the data sheet,
Noise pickup is due to the proximity effect of the radio cards antenna terminals and PCB tracks, which cannot be screened 100%, when one radio card is in transmit mode the other maybe in receive mode, internal RF signal pickup is going to happen…
Thank you for your reply, I’m learning a lot 
What product do you suggest for integrate AP?
I have a preference for MIMO AP’s
http://www.itelite.net/en/Katalog/MIMO-80211-n//PRO-SECTOR50018dual-HVBOX.html
Others may advise of equally good AP’s
P.S. Don’t forget to give Karma for good advice given on the forum
its possible to use X polarity antennas in mimo
Go to rfarmor.com
They work!
With multiple cards in one board keep your tx power at 20 or below. Helps tremendously.
Multiple cards using the same frequency band in the one board is a bad idea.
No argument, but once the cards are there, you can swap the AP to get it working or you can drop the TX power.
I have 3 R52H in a 433 since I started in 2008. The self interference issue has been better or worse depending on the version of RouterOS, but since I had several pieces of hardware in the air with multiple cards in single boards I learned what to do to make them work.
Essentially, if you scan from one card and see the other in the same band with a signal greater than -40dB you will have issues. For 2GHz and 5GHz, setting the tx power below 20dBm gets the signal level close to -40 depending on the cards, pigtails, etc.
I’ve found that low power cards have much less self interference issues than high power cards. R52 work fairly well in the same board, R52H do not. I haven’t tried this with newer cards without diversity chips. The lack of a diversity chip should help shield the signal a bit more inside the case.
I’ve also learned that running multiple XR5 in a single board has much less of a problem than the R52H. I’m not sure if it is due to the pigtail/coax (MMCX vs UFL) or the lack of a diversity chip. Either way, at default tx power, two XR5 in a single case see each other around -40dB in the 5GHz band. Two R52H see each other at -20dB, I’ve even seen signal in the teens before.
Interesting about the XR5’s have you tried with one XR5 if using say 5520 to set frequency scan to 5500-5540
and another XR5 if using say 5700 set frequency scan 5680-5720, then set TX to default and check if interference effect is reduced?
Hi everybody
I have a ptp link in very noisy environment . Tx rx are -49/-50 but throughput is 1Mbit .
Is there any solution ? ( I know I should change frequency . Not this solution )
Hi everybody
I have a ptp link in very noisy environment . Tx rx are -49/-50 but throughput is 1Mbit .
Is there any solution ? ( I know I should change frequency . Not this solution )
That depends what is real reason of your low throughput. You didn’t share much info.
- what noise floor and SNR do you see on both ends?
- what CCQ is on both ends?
- as it is ptp link, what antennas do you use?
Distance?
Frequency?
Recommend speed