Odd, are the newest TVs manufactured completely without an antenna input and tuner? You have the following options:
1. Find someone who sells a video cable, either composite or S-Video.
2. Build one yourself, requires a bit of soldering skills.
3. Find a generic 5-pin to RCA cable, use a multimeter to identify which pin goes to which RCA plug, cut off the ones not needed and plug in the rest. You would get a better picture quality than the RF/antenna option, but not quite as high as you would with the separate video option.
Or of course 4. Get another TV that has an antenna input, if your TV lacks one. It could come handy if you are going to buy other vintage home computers that assume an antenna input. If you have an old VCR or some other equipment with antenna input and tuner, it could also work.