Actually sorta that but maybe not in the way you meant it: it's unlikelly that the drone will be in communication with the home base as it's supposed to be autonomous and besides the whole radio thing is commonly used to detect enemy forces so it's the kind of thing any decent system designer would think of, plus GPS receivers are passive - they merelly listen to signals from satellites and use them for triangulation - so there are no emissions from those either.

However, every electric thing does emit some amount of noise in the radio spectrum and the engines possibly also (due to the sparks used to ignite the fuel), so maybe a ground-based wideband receiver with a directional antenna (and it doesn't even need to be a narrow reception window) aiming with the appropriate angle up (basically just enough to stop detecting ground-based devices) will detect them as, even though the signals are weak, there is normally nothing in the air that emits signals quite like that all the way up to Low Earth Orbit (and maybe not even there if the sparks in the engine are what is being detected). Other possibilities involve balloons as there are antenna configurations which allow avoiding catching signals from below, so the "line of sight" of a balloon (just tethered in place) for detection is probably quite long.