This is the fourth article in our continuing series of biographical pieces with a technical lean. The subject of this paper is Professor Arye Rosen, who -while employed full time at RCA Sarnoff Research Laboratory as an engineer and working on the side more-or-less as a "hobby" -pioneered the use of microwave angioplasty and ablation techniques in cardiology, and later influenced the use of microwaves in the treatment of benign prostatic hyperplasia (BPH). Dr. Rosen's life story is as varied and interesting as his career path, and his contributions both to traditional microwave devices as well as microwaves in medicine will definitely inspire those of you who feel like they are pulled in more than one direction professionally. In Dr. Rosen's case, he did "have it all," but he worked very hard to make it happen and he took lots of chances …as you will hear! INDEX TERMS Microwave pioneers, Arye Rosen, microwaves in medicine, balloon catheter hyperthermia.1 This article was compiled after two wonderfully entertaining interviews with Dr. Arye Rosen -he used an iPhone no less, on March 3 rd and 5 th , 2021. Normally, the interviews would have been face-to-face, but Covid 19 restrictions forced their conversion into Zoom video conference sessions. Dr. Rosen was in his residence of many years in Cherry Hill, NJ where he could somewhat reasonably commute between Princeton, NJ (