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As we know, a user equipment (UE) can transmit its traffic with the power up to 23dbm. However, there is few materials mentions the maximum power a UE can apply if it has multiple antennas.

In this paper: https://www.researchgate.net/publication/344886461_Joint_Power_and_Resource_Block_Allocation_for_Mixed-Numerology-Based_5G_Downlink_Under_Imperfect_CSI It seems they assume different antennas have their own maximum power constraint; i.e., each antenna can transmit its data with the power up to the maximum value (e.g., 23dbm). Nevertheless, this indicates that if more antennas are used, more power will be required.

Is it the truth? Or in fact all the antennas share the maximum transmission power (the sum of the transmission power of all antenna should be less than the limit)?

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It depends on how you feed the antennas and how your transmitter is made.

  1. If you have a single TX feeding two antennas, this can be done only with a power combiner, so sending 50% of the power to each antenna (and loss in the combiner!)

  2. Instead, with a specific TX for each antenna, what you say can happen: you can feed as much 23 dBm "streams" as TX outputs. I have recently worked with a train-wayside application using 4 antennas fed by 4-output provided by a router that is a 4G/LTE/WiFi router (https://www.teldat.com/telecommunications/transport-routers/telecommunicationstransport-routersteldat-h2-rail-railway-train-metro-router-lte-4g-3g-wifi/). I put a screenshot below: the first four N connectors are the RF TX output to feed 4 antennas, independently. enter image description here

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  • \$\begingroup\$ Thanks! I think I got the point. I will check for the specific design to see which scenario my case accommodates. \$\endgroup\$ – Yukinari May 29 at 14:56

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