"Usually in the boonies" - I picked up a 19" LED TV that used a wall-wart to drop the voltage to 12v DC. It was $99. I use this in the bedroom for those stop overs where I'm on batteries only. I just leave it plugged into the 12v cig socket even in a campground. LED's will use less battery power.
"HD Antenna" or "Digital Antenna" are just buzz words. A antenna is a antenna. They capture signals of the designed frequency or wavelength.
Your old TV antenna has some mechanical issues with the lifting mechanism. It might have a amplifier that uses 12v for power. They don't work well at all with the amplifier turned off. I have built many a TV antenna out of PVC pipe, 12ga solid copper house wire and some TV antenna alum elements that work great for stationary applications. The crank-up bat wing is a proven RV antenna and they still work. Pointing of the antenna is critical for good reception. Once you achieve capture of a signal use the on screen signal strength meter and rotate the antenna for maximum singal strength. Where we stay in FL I can get signals from Orlando or Tampa by changing the antenna direction.
The pictures on my antenna are actually better quality than I get from the sat dish.