I updated 4.91 to 5.14. I did the 'update to 5.14' thing ingame.
One day later I found out there already was a 5.20 Patch, so I installed that.
Weird thing is: the 'update to 5.14' option is still available from the dropdown menu.
Also, indeed, the narrowband sensors seem not to be in the game, except for the research line. I've researched it as well, but there's no option to be seen anywhere in the sensor design window.