Tried using a portable handheld radio in a car. During several trips in a passenger car, it turned out that the diameter of the magnetic base is critical, I recommend using a base wider than 5 "and using an external microphone for ease of use of the radio. The antenna was dual-band, stood on a magnetic base. With a magnetic base diameter of 4 ", the safe speed of movement is approximately 55 miles per hour. To connect an external antenna, you need an adapter between different antenna connectors. I recommend using a power adapter for the radio for long-term use in a car. I will not name the exact models of magnetic bases and VHF \ UHF antennas, since I do not live in the USA.