This isn't always the case.Some times the problem can be something much more simple,like a loose co ax plug,damaged cable.
Old co ax cable can be another problem,linking through a video recorder that is past its best.
Digital can fall over without very much pushing,and is not tolerant of say a slight bit or water in the co ax cable.cables can start to leak water after a no of years.
Sunlight breaks down co ax cable and makes it brittle,especially cheaper stuff that is fitted by many electricians who are not versed in the types available,in fact fitting an improved co ax cable rather than a total new aerial can of ten improve the situation.
Summing up don't,automatically lay the blame at the Aerials door,something far smaller and cheaper can of ten be the culprit,rather a full tv aerial installation.
If you have picture break up or freezing contact us so we can run through your problem,we are always willing to discuss without putting you under pressure,could well be something smaller and much less involved than a new Aerial.