Depending on your aerial check how other caravan owners have theirs angled and imitate, then ensure the amp (often hidden in the wardrobe or locker near the aerial) is switched on. Often there is a co-ax cable ready wired - mine emerges by the front drawer unit. I also have a small digital amplifier bought for about 10.00 (One for All SV9601 One Way Digital Freeview TV or Radio Signal Booster Amplifier) that seems to help in weaker signal areas. Setting the TV on site for me can be more frustrating than the awning!