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?