As a long time researcher into early radio I'm afraid I find this article spurious in the extreme! The "FM" radio using SPARK! Are you kidding? It looks very much like Collins early work where he claimed to transmit AM voice using a spark transmitter at the same period. That has long been shown to be utter nonsense. In fact I have built and operated several spark TX's for historical demonstrations and I KNOW , not just guess, that such a system will not work. Certainly Armstrong was working in parallel with others as in the case of the regenerative detector with Round and Meissner and there are antecedents in French work which might have led to the superhet. But to imply that he stole ideas from RCA harks right back to the notorious long running patent fight which helped to bring about his death. In the end despite many obstacles Armstrong built an demonstrated FM radio for the first time as a practical system. It is NOT just a case of putting a far fetched idea on paper, otherwise Cambell-Swinton would be the inventor of electronic TV in 1913. There is the little matter of making it work and showing others that it does.