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Dear Sirs,

I want to connect a single, multiband antenna to the WIFI & LTE Main connection. To achieve this I was thinking about using a Combiner/Divider (e.g. the InStock PD2020). This is a basically a power-splitter/combiner covering the desired frequencies. It has a channel isolation of 22dB. Since the WIFI and LTE frequency in use are very close, the use of filters with their crossover between WIFI and LTE is not possible. But with the combiner, a small RF signal will 'leak' back into the LTE input/output when transmitting on WIFI (and the other way around). Now this will be 22 dB attenuated with respect to the WIFI or LTE output signal.

Can you tell me if the WIFI and LTE input/output are immune to these 'out of band' signal levels ?

I'm looking forward to your response :-)

Kindest regards from The Netherlands

Peter

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Hello,

Since RUT950 supports only 2.4 GHz WiFi, it operates in the 2.412 GHz to 2.472 GHz range (plus 20 MHz protrusions on both sides) or up to 2,484 GHz if you're in Japan.

The closest widely used LTE band to this is LTE band 7, which uses:

 

Downlink (MHz)
Low Middle High
2620 2655 2690
Uplink (MHz)
Low Middle High
2500 2535 2570

So they don't really intersect.

You can find some information on what antennas can be used on RUTxxx routers here: https://wiki.teltonika.lt/index.php?title=Can_I_use_LTE/3G/Wi-Fi_antennas_other_than_Teltonika%27s%3F

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Hi,

I know these bands do not intersect. My question is about RF energy from the WiFi connector flowing back into the LTE connector when a (passive) Power-combiner/splitter is used to connect just 1 antenna to both WiFi & LTE. As mentioned this device has 22 dB isolation, so when the LTE would transmit at 2W output this would 'leak' back into the WiFi connector at 12,6 mW (= 2W x -22dB). Does this damage the routers WiFi output ? (the same question applies for the LTE output when transmitting via WiFi).

Peter
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Hello Peter,

You are not 100% correct saying that LTE would transmit 2W. 2W is maximum power for GSM and LTE maximum power is 23dBm (200mW).

Our router has 2.4GHz bandpass filter in WiFi chain so transmitting power of GSM bands will not affect it. Meanwhile there are some LTE bands that frequencies are very close to WiFi but it's power is 23dBm max. After your splitter with 22dB isolation power transmitted from LTE to WiFi path will be only ~1.26mW. Such small power will not damage WiFi so please don't worry your router will be fine. :)