Not to be pedantic, receiving is actually traceable to a motivated enough agent with sufficiently expensive equipment, especially if your receiver is home made or poorly built, due to oscillator leak back, there are a few other effects that can be used such as shadow casting. This gives a light idea of what’s possible: https://ham.stackexchange.com/questions/2160/is-there-a-way-... I simply mention this because in some regimes and some situations, it’s best to understand what’s possible.