If you have terminals for an antenna connection, I'm wondering if you need this as well:

https://www.amazon.com/RCA-VH54R-Matching-Transformer-VH54R/dp/B00005T3EY/ref=pd_aw_sim_23_3?_encoding=UTF8&pd_rd_i=B00005T3EY&pd_rd_r=7fae14fc-c205-11e8-a606-db11b044450e&pd_rd_w=1hyRH&pd_rd_wg=P2kcd&pf_rd_i=mobile-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=b4933956-4edb-4091-a456-e7deb088900e&pf_rd_r=6WD5AAF9TZNM7H1G4M2P&pf_rd_s=mobile-dp-sims&pf_rd_t=40701&psc=1&refRID=6WD5AAF9TZNM7H1G4M2P

I think the antenna input is slightly different than a coaxial cable input and this transformer matches it. I have no real clue though - I'm trying to figure this out for myself as well. I just bought an old TV that I plan to use with a pi as well, and it only has UHF and VHF antenna connections. I haven't been able to test it out yet though.