This actually, is quite simple. Radio waves are part of the 'electromagnetic spectrum' and as such propagate at the speed of light. If a radio wave is moving faster than the speed of light it simply, is NOT radio. Now, even at the speed of light a radio transmission travels 186,000 mps (300,000 km/ps) no faster, no slower. If the person you are communicating with is within 186,000 miles the conversation seems to take place normally. For every extra 186,000 miles apart the conversation seems to have a 2 second(one going, one coming) delay. So, if you are several light years from the person you are wishing to talk to then it will take that same amount of years for your transmission to reach them, and that same amount of years for the return transmission to get back to you. Just to say "hi" to a person one light year away means it will be 2 years before they can be heard to say "hi" back. This method of conversation will never work!
