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The goal is to connect an LTE ("4G") signal booster (amplifier) directly to my router to avoid the radio signal feedback¹ by the LTE ("4G") signal booster (amplifier).

¹ Interference caused by the LTE ("4G") signal booster (amplifier) signal itself between the outdoor and indoor antenna.

I don't understand anything about radio frequency so I think this will break my router.

Is there any way (or device) to do this correctly?

IMPORTANT: My LTE ("4G") signal booster (amplifier) is not designed to connect directly, but to use an internal antenna. So I want to try a strategy (or some sort of device) to get this right.

NOTE: This is my LTE ("4G") signal booster (amplifier) model: https://pt.aliexpress.com/item/1005002977521199.html?spm=a2g0o.order_list.order_list_main.11.2483caa4NI0ADp&gatewayAdapt=glo2bra .

Thanks! 🤗

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There is no way to do it correctly, as it is almost always illegal. If you do that - you break the law, as you can emit signals on frequencies and power levels that might (and likely will) interfere with other users. Also, it will likely not work, unless you accidentally match frequency plan of your local provider.

Best relatively safe way is directional antennas that can be connected to 4G modem or router with 4G dongle.

Unlikely theoretical way for direct connection of booster to 4G modem is using some 30-40-50dB attenuator. Unless you are in a war zone - there is no justification of attempting that.

Try your best luck with external directional antennas, it's your best bet. If you are very far from cell stations - you can use parabolic antennas, there are numerous guides around internet.

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    $\begingroup$ none, as BarsMonster says, there's no justification for this. Even if it technically worked (which I heavily doubt – LTE isn't as easy), you'd just win nothing, as you can only increase the output power of your side, not that of the base station. Also, I was not aware that brazil was permitting any extraordinary EIRP for LTE; I don't think it is allowed as you claim. $\endgroup$ Dec 21, 2022 at 14:36
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    $\begingroup$ @EduardoLucio the magic is the dish. Not the "booster". Not judging anyone. I'm a communications engineer; I professionally judge RF communication systems, I don't usually judge humans $\endgroup$ Dec 21, 2022 at 15:04
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    $\begingroup$ These numbers are meaningless with active amplification in between; of course you get more receive power, but what matters is always how much that improves your SNR; and with an active amplifier in between, you always get a non-zero noise figure, and hence only, and ONLY, iff the noise figure of your 37€ amplifier is better than that of your router's LNA, a net gain. I can, however, tell you very good thing about noise figures of LNAs and bad things about the noise figures of power amplifiers, but that would shatter the sales arguments of the booster manufacturers ;) $\endgroup$ Dec 21, 2022 at 15:19
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    $\begingroup$ From all these measures, hence, the only two matter: SINR (and 12 dB is really not good in 4G context), and maybe RSRQ, but I don't think that helps MCS much when you've got an SINR of only 12 dB. $\endgroup$ Dec 21, 2022 at 15:21
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    $\begingroup$ So, if you really want to increase service quality, you will need the same (probably: better!) duplex filtering as done by your booster, and instead of something promising a pretty questionable 20 dBm output power in RX, you'd want something with less drastic gain, but a very low noise figure, close to the antenna in RX direction; and something high-output-power, medium gain, close to the modem, in TX direction, assuming there's long cabling between dish and router; if there's no long cabling, you just don't want anything between your router and the antenna. $\endgroup$ Dec 21, 2022 at 15:24
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BEST SOLUTION:

As stated here in comments your best luck will be using a good directional (satellite/dish) and multiband antenna (I don't recommend "fullband"). This antenna must preferably be in a high, stable, barrier-free place and correctly directed.

IMPORTANT: Maybe satellite/dish antenna is not the best solution. Possibly, a solution using two LPDA (MIMO and XPOl) is better. For more details (see comments). There is a specific thread about this subject.


ANSWER:

If you really want to push the signal amplifier approach (beware of legal issues in your country) you will need two 40bd 5w attenuators (one for each direction).

NOTES:
I - The antenna approach ("BEST SOLUTION") is essential.
II - The signal amplifier must be multiband (I recommend "fullband").
III - I insist that there are no guarantees that the signal amplifier will bring performance gains.


EXTRA:

In addition to a good antenna ("BEST SOLUTION") you can use multiple 4G (LTE) modems (routers) connected to a connection balancer (prefer Gigabit Ethernet). These modems may be connected to the same antenna by a power divider (pay attention to the frequency range).

This approach is sure of good results.


Thanks! 🤗

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