Common cable sizes are RG6 and RG59 and your caravan may use a combination of different sizes.
RG59 cable has been around for a long time. This cable used to be what most people used for their cable TV connection. However, modern signal requirements have made this cable less popular in the last few years. RG 59 has a smaller conductor than RG 6, which means that it can’t achieve the same signal quality as RG 6. The way its shielding is designed also means that it doesn’t keep Gigahertz level signals inside the conductor very well. This is why RG 59 probably isn’t a good choice for your TV or internet connection.
All of the new demands required by, satellite signals and broadband internet made it necessary to find a more effective coaxial cable. RG6 cable was designed to fulfill these requirements. It has a larger conductor, which gives you much better signal quality. The dielectric insulation was made thicker as well, which means it is much less likely to carry an electric current that could damage your sensitive electronics. RG 6 is also made with a different kind of shielding, which allows it to more effectively handle Ghz level signals.