Television

We have just bought our first caravan and had our first outing this weekend which was excellent but we couldn't get our television to work. The caravan itself has a built in aerial which looks like a spaceship on top and I have seen these on many caravans so don't think this is the problem (the red light in the wardrobe stating it was working was also alight) and our television was from home so we know it is in full working order. I retuned etc but it claims 'no signal.' This may have been the campsite itself which didn't pick up a signal but we wondered if there was any kind of booster we could buy or how we could check before our next 4 day trip next week. The previous owner is a distant friend of mine and confirms they never had any problems with television so we are at a loss. 

Sorry for rambling. Can tell I am new to this.