Is it possible to completely disable radio signal in a phone without a SIM card? I have a Samsung Galaxy S4 Mini, powered by CyanogenMod 13 (Android Marshmallow 6.0.1), which I use as Wi-Fi only, being it without SIM card.

The device antenna, though, seems to be constantly connected to a cellular tower, so I'm afraid that this fact may result in an increased battery consumption (even if slight, that is). Plus, I don't want my position to be triangulated due to this behaviour.

Simply dialing *#*#4636#*#* and disabling the antenna from there seems to suffice, but the change does not persist between reboots, and repeating all of the procedure each time is a nuisance.

What I wish for, is a way to make the abovementioned change persistent, without the need for a whole app, which I deem overkill for such a simple task. Even better, I favor a solution that makes use of the built-in Terminal, be it a single command or a function, and I'm open towards solutions that require root access.

Is there such a way to accomplish this?
Use airplane mode to disable the cellular radio. This is simple and does not require an app, use of terminal, or root access.