what i need for tv signal

I see you live in Texas. I am pretty sure that no where in the US are the broadcasters allowed to send out non Digital tv. Even for over the air free broadcasts. FloTV was popular for a brief time for this reason, but it was pricey both in hardware and subscription fees for what it was (a single use device). If your radio is an ebay special with included tv tuner it will not work. The frequencies those units are looking for are no longer being broadcast in the US. If the unit has an aux video input you may look into things like satellite tv (direct tv has a service for this). Another option is a smart phone with an HDMI output running netflix or equivalent apps, though that would use a significant amount of data on long trips.

You can still buy Digital TV converters at most retailers, but they are designed for home use and may require a power inverter, as well as having large ugly antennae. Again after all that expense you may get less than 10 channels and you will constantly be losing and gaining stations on interstate trips.