If the TV signal in your area is reasonably strong, you can try getting an antenna that plugs directly into the TV. Many of the newer set-top antennas are flat and can be hidden behind a cabinet, picture frame or even the TV itself:
If you have a satellite dish, you may be able to use an existing coaxial cable to carry both the satellite and TV signal using a diplexer. In the room with the TV, you would connect the cable to another diplexer, which splits the TV and satellite signals out to two leads again. In the UK and Ireland, this will work with Free-to-air, Freesat and Sky dishes, with the exception of Sky Q.