Hello.
I have several devices that I use in my daily work, e.g. RUTX12, RUT955, RUT950, etc. In the past, I was taught that all radio devices should ALWAYS work with an antenna connected because its absence can cause wave reflection in the connector and heating of the radio transmitter elements, ultimately leading to its damage. Normally, when the antenna is properly matched, this energy is dissipated by it. However, I wonder if this is still required in modern, multi-antenna designs such as RUTX12?
Maybe it is enough to only use antennas whose functions are enabled in the device?
For example, if in WebGUI we disable all functions except for the mobile network and LAN ports, we do not have to install WiFi or BT antennas? All the more so not installing a GPS antenna should not be a problem, after all, here we only receive the signal and do not transmit anything, so no energy will be additionally dissipated in the form of heat…
I ask because some time ago my long-used RUT950 broke down, which was working without WiFi antennas because this function was disabled in WebGUI and I wonder if this could have damaged it…
Someone may say that this is a rare problem and it is enough to check that all unnecessary functions are disabled in the device settings and then we only install antennas for the functions used, BUT what happens when the OS is just loading, because e.g. the device has a reboot set to no ping with some host and does it often for some time? When the device starts up, are these previously disabled options not active and can lead to weakening of the radio modules or even their damage?
I really hope for a detailed and technical explanation of this issue because maybe technology has advanced so much that all kinds of transmitters/modems verify at startup whether the antenna is connected and in the event of its absence they protect themselves from damage?
In my case, a common problem is also the lack of free space to mount the device with all the antennas, so if it were possible to use it safely only with the number of antennas used it would be worth its weight in gold 
Thank you in advance for your help and a clear answer.