Dear Q.
From my laymans viewpoint I will offer a perspective as a tiny piece of the whole picture.
In the early years of analogue mobile phones, antenna design change made improvements to signal quality , handset signal strength send and receive.
Since going digital, the antennas appear to have become a lot smaller.
There are TWO distinctly separate systems in a mobile phone handset - the Radio and the handheld computer. All custom rom mods i have seen only appear to play with the handheld computer………
A whie ago I took a copy of the ROM in my Samsung Core Prime phone (2015/2016 model). Unpacked it, then unpacked the Bootloader. ONLY some files were readable in there without more specialised software ans knowledge.
In the Linux SE section of settings in the Bootloader there were found some annotated entries that said:
Added at request of NSA
Added at request of Chinese Government
On the Radio side, that silicon hardware is known very little about in general outside specialised knowledge, some sources say it has its own built in software. This seems similar to the Intel ME engine management system whereby as long as only power is on to the mainboard, the secretive ME engine can and does communicate (bypasses system CPU) through the network.
Refer https:// software.intel.com/en-us/node/632310 on how to access that from your browser. The true depth of it most of us will never really know.
In Mobile phones, as the RADIO portion is separate engine to the rest , i suspect only those with specialised security clearance and knowledge could provide insight to what is truly baked into the silicon and secretive firmware that could and might give remote monitoring of attached sensors to the device without any user interaction nor knowledge, and is likely to fall into specialised arena of TSCM few would truly be aware i suspect is the case.
That would mean, the successful marketing of a device to have a population voluntarily carry and be attached to emotionally , is a perfect weapon to selectively produce the waveforms and frequencies required for control or provoking individually or enmasse and few would be the wiser as that technology was introduced gradually (but quick enough) to be adopted.
An effect, refer fitbit capture data presented recently as movement heatmaps, that data given freely under the guise of " healthy" and self monitoring aware whilst a greater effect is at play.
The question is, just what can the radio section of a mobile truly do in terms of frequency and waveforms that remain undocumented, and how is the human psysiology altered with big pharma as a carrier to enable the desired effect of the specialised waveforms and frequency combinations.
Just my laymans view :)