Mixing antennas between phone signal booster and WiFi router

[azaxi]

I have a question about feasibility of following scenario:

Have a trailer in the woods in very poor phone signal area, so I successfully installed phone signal booster inside and placed receiving antenna high outside. Now I get 4 bars inside.

Now would like to have good phone signal even when outside, but trailer has metal walls, which shield EM so currently I am not receiving any of that boosted signal outside trailer. So I would like to install 3 way signal splitter to booster output and 3 antennas - 1 inside as its been so far and 1 on each side of the trailer.

If this works and I already have phone coverage inside and outside using the 3 retransmitt antennas, I would like to use these same antenna for WiFi. The signal splitters are bi-directional, so they should work as mixers as well, so the 3 antennas should work for WiFi at the same time. GSM bands are not overlapping with WiFi, so these two devices should not be interfering with each other either.

I realize I will need splitters/mixers and antennas that work from 700Mhz through 2.5GHz and that new signal levels from the booster will be slightly lower as it will be shared by 3 antennas. I am only planning to use 2.4GHz WiFi.

Note: I am not sure how booster deals with feedback from output back to input, but ideally, booster receiving antenna should be directional and pointed to cell tower. This is not the case as booster came with omnidirectional stick type.

 

[rjenkinsgb]

Not a good system...

The cellular booster and WiFi, both trying to transmit to the same antenna, are likely to block each other at a minimum, or just burn out each others receivers due to the power levels being fed in to them via the opposite transmitter.

Also, by using a single cable to each device, the antennas will act as a single unit with strange directional effects which vary depending on the frequency involved (due to the different signal wavelengths interacting with the antenna spacings).

Depending how the booster works, putting both its antennas in sight of each other may cause it to just lock up or lock in to one way only, like an audio amp feedback howl?

You are far better off keeping the two systems isolated & antennas well separated, and I'd suggest adding an outdoor rated auxiliary WiFi access point, linked to the main one by ethernet.

Also note that passive splitters / combiners typically reduce the signal strength a lot. Plus, cable losses are quite high a the frequencies involved.

Most newer WiFi routers or APs have dual diversity at a minimum using two antennas, or the later WiFi6 units have "beam forming", being able to electronically steer the antenna gain towards each device they communicate with.

Those only work with two independent antennas, or the built-in ones, for WiFi6,

 

[azaxi]

Not a good system...

The cellular booster and WiFi, both trying to transmit to the same antenna, are likely to block each other at a minimum, or just burn out each others receivers due to the power levels being fed in to them via the opposite transmitter.

Was hoping to run one set of antennas and cables. So I will build budget two independent systems then.

Depending how the booster works, putting both its antennas in sight of each other may cause it to just lock up or lock in to one way only, like an audio amp feedback howl?

It is not happening right now, but the input GSM antenna is outside and the re-transmitting one is inside so there is a shield between them. I may acquire a directional style later if this becomes a problem.

I plan to put outside retransmitting antennas on the walls under soffit, and because roof is also metal, there will always be a shield between input/output GSM antennas

Most newer WiFi routers or APs have dual diversity at a minimum using two antennas, or the later WiFi6 units have "beam forming", being able to electronically steer the antenna gain towards each device they communicate with.

Those only work with two independent antennas, or the built-in ones, for WiFi6,

I don't need any of the new tech, the WiFi3 is enough. Also don't need to cover huge areas, trailer is about 700ft2 and covering about 20-30ft around the trailer would be sufficient.

Looked at my home router, an old Cisco EA4500 without external antennas, running OpenWrt, power level is automatic and currently sitting at 18dbm (63mW) and covers entire house. I currently see 4 other WiFi networks from neighbours, we are on street with 50ft wide lots, it probably gets worse in townhomes and apartment buildings. The trailer is sitting in radio deadzone, my WiFi will be only one in the area.

Thanks for the advice. I will plan for independent systems and some distance between WiFi and GSM antennas.