The antonyms for the phrase "radio activate" can be numerous, as it depends on the context in which it is used. In some cases, antonyms may include "radio silence," which denotes complete quietude and lack of communication. Alternatives may include words such as "deactivate," "power off," "shut down," or "disengage," all of which indicate a cessation of activity or an end to the transmission of signals. These terms may apply in various contexts, including the military, scientific research, and commercial applications that require the use of radio frequencies or electromagnetic waves. Ultimately, the antonyms for "radio activate" reflect a range of situations where the use of electronic equipment is not required or possible.