Could I invent the radio if I were flung back into the past 2000 years? How?

A2A Can I invent the radio if I have been back to the last 2000 years? How?

At the end of the 19th century, the world began to communicate over distance thanks to telegraph and telephone technology. Both telegraph and telephone were due to wiring to carry a signal from one point to another. The term radio was originally called "wireless" as it suggested telegraph and telephone signals that were transmitted through the air without using the wires!

If I went into a time machine and took my amateur radio transmitter and my smartphone back to the last 2000 years how many people would understand how to use these devices?