Complex sentence: The invention of the TWT is widely attributed to Rudolf Kompfner in 1942--1943, although Nils Lindenblad, working at RCA (Radio Corporation of America) in the USA did patent a device in May 1940 that was remarkably similar to Kompfner's TWT.
Split into simpler sentences: The invention of the TWT is often attributed to Rudolf Kompfner in 1942--1943. In addition, Nils Lindenblad, working at RCA (Radio Corporation of America) in the USA also patented a device in May 1940 that was remarkably similar to Kompfner's TWT.