IPA: /ˌʌnəˈtɛn.ju.eɪ.tɪd/
KK: /ˌʌnəˈtɛnueɪtɪd/
Not weakened or reduced in force, intensity, or effect.
The unattenuated signal was strong enough to reach the receiver without any loss.
Unattenuated → It is formed from "un-" (meaning not) and "attenuare" (from Latin, meaning to make thin or weaken). The word "unattenuated" means not made thin or weakened, retaining its original strength or intensity.
Think of 'not' ('un-') making something 'weaker' ('attenuare') — that's why unattenuated means something that has not been weakened.