Dr. William S. (Red) Ament, 61, a physicist for the Naval Research Laboratory's communications sciences division, died of cancer March 12 at George Washington University Medical Center.

Dr. Ament was considered an expert on Einstein's theroy of general relativity and had earned an international reputation during the past 36 years for his work on electromagnetic wave propagation.

He had worked for the Naval Research Laboratory since about 1945 and, in 1959 and 1960, was assigned by the laboratory as a scientific attache to the U.S. mission in London. He also had worked for the Electromagnetic Research Corporation in College Park for about a year and a half in the mid-1960s, before returning to the Laboratory.

Born and reared in Pomona, Calif., Dr. Ament graduated from Pomona College there in 1939. He earned a doctorate in applied mathematics from Brown University. He lived in Washington.

During World War II, he was an ensign in the Navy.

Dr. Ament was a senior member of the Institute of Electrical and Electronic Engineers and had contributed numerous articles in his fields to scientific publications.

He was a recipient of the Navy Meritorious Civilian Service Award.

Survivors include his wife, Marion, two sons, William and George, and two daughters, Helen and Anne, all of Washington; his mother, Eleanor Hill Dodge, and a sister, Emily Ann Starr, both of Claremont, Calif.; and a brother, Richard P., of Ann Arbor, Mich.