William Le Queux 
Voice from the Void: The Great Wireless Mystery 

Adventure, romance, and fear. All rolled up into this neat little book by William Le Queux. One of my First published in 1922, this novel by best-selling author William Le Queux is a mystery around a wireless machine. (i.e. a radio). A young man who happens to be an amateur radio enthusiast is walking home one night when he comes across an injured young woman in a forest begging for help. She dies in his arms, and he goes for help – but he then disappears. When he is found, days later, he seems to have lost his mind and memories, and no one can find the body of the girl. He is determined to find out what happened. A mysterious woman named Freda, who his father warned him about, is determined that he never will. (Amazon)