You can use any type of digital-to-analog converter box for your vehicle, as long as you can provide 120v power to it from your car battery or cigerette lighter. If you do not have excess storage/room to store the converter box in your car, I suggest the following compact converter boxes:
Do you have an extra outlet for 120v power (it's possible since your TV is probaly using 120v to power it)? If not, you will need an inverter (changes a car's power from 12 volts DC to standard 120 volts AC). Some of the inverters sold for cars have adapters which will allow you to plug into a cigerette lighter.
If you don't think you'll use the converter often, the Winegard RC-DT09 has the capability to run on battery's (for up to 18 hours) if you purchase the optional battery pack for it.
i have a converter box hooked up in my truck. my kenwood kvt-911 has a 7inch screen with a tv tuner. i have hooked up a standard antenna and amplified antenna, when i am parked, the signal is 87% but as soon as i start driving the signal goes down to 0! is there a way to fix this? my analog signal worked fine while driving. i really want to keep my signal while driving. i cant find an answer anywhere online.
Be careful when connecting it to your car's electrical system though. At the very minimum I would use a 7812 3 terminal voltage regulator and a fuse. If you really want to get fancy you can use one of the switching regulators (I use one called the W4RRY battery booster) that can compensate for both high AND low voltage and deliver a steady 13.8v. A car's electrical system can put out anything from 11v to 16v but usually puts out 13.5-14v when running.