Dr. Henry Sampson did not invent the cellphone, but he did invent a number of advances in solid-state rocket propellant and a gamma-electric cell for generating electricity from gamma radiation. The invention of the cellphone is credited to Dr. Martin Cooper.
Although Dr. Sampson's 1971 patent for the gamma-electric cell is sometimes cited as the invention of the cellphone, the two inventions are entirely unrelated. A gamma-electric cell would be a very inappropriate power source for a handheld consumer product, as gamma rays are very damaging to the human body. In addition, Dr. Sampson's invention was a gamma ray detector, not a power generator or battery for portable use.
Dr. Cooper developed the Motorola Dyna-Tac in 1973. It was the first truly portable phone, using a base station to relay phone calls into the landline-based phone system.