The simple answer to your question is No; you should not use the cable that is attached to your RV's TV antenna to hook up your RV Satellite Dish. Satellite antennas require the use of RG6 coaxial cable and your RV TV Antenna in all likelihood is using RG59 coaxial cable.
If you use RG59 cable with your satellite; the satellite signal will deteriorate quickly. The longer the run of cable the more the satellite signal will deteriorate.
Normally when you buy a Satellite Dish System it comes with an installation kit that contains the proper cable for satellite use. Some newer RVs are already pre-wired with RG6 coaxial cable for a satellite installation.
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