I am asking two questions to improve my understanding of electromagnetic energy transported into free space from current in a conductor. At one time I thought all such energy was considered electromagnetic radiation (radio waves) but I think this is wrong. When Hertz did his original experiments in the 1880s that proved the existence of waves predicted by Maxwell in 1865, he used a spark-gap transmitter and a remote circular receiver.
First question -- How did Prof. Hertz know that the sparks appearing in his remote receiver were not caused (1) by induction (as described by Faraday) or (2) by what today is called "near-field radiation?"
Second question -- if we repeated Hertz's experiment with the circular receiver, but we kept moving the receiver farther away from the spark transmitter, what behavior would we expect to see in the receiver?
Let's say we start with the receiver physically adjacent to the transmitter and then keep moving it away in 1-foot increments. What response would we see in the receiver at each increment? Regarding terminology, is it scientifically accurate to describe the energy emitted by the transmitter as EM radiation, regardless of the distance from the transmitter? Thank you kindly for considering this request for clarification.