William E. Yost Jr., 59, chief of the radar branch of the Army Foreign Science Technology Center in Charlottesville, died of cancer Saturday at his Charlottesville home.

An electronic engineer, Mr. Yost specialized in tropospheric scatter (troposcatter) communications, used at ultrahigh and very high frequencies for ranges beyond the line of sight, and had developed innovative techniques in this field.

Before joining the Army center in 1970, he worked for a number of electronic and engineering laboratories in this area, and as a private consultant.

He was the senior project engineer on the Air Force's ionospheric scatter programs spanning the Arctic and North Atlantic for Page Communications Engineers of Vienna, Va.

Mr. Yost was born in Washington. He graduated from Roosevelt High School in 1937, and attended Rensselaer Polytechnic Institute in Troy, N.Y.

During World War II, he served as a lieutenant in the Army Signal Corps in Europe and in the Pacific theater and taught at the Southern Signal Corps School at Camp Murphy, Fla.

He contributed to the development of the "synchro-lock" horizontal control for television and wrote numerous articles in his field, including a history of the troposcatter for Spectrum magazine in 1966.

His professional memberships included the American Association for the Advancement of Science.

Survivors include his wife, Evelyn, of the home; a son, David, of Los Angeles; three daughters, Lynn, of New York City, Camilla King of Silver Spring, and Brenda Ellowitz of Los Angeles; three stepdaughters, Cynthia Houchens of the home, and Gloria Ward and Judy Dodson, both of Charlottesville; two stepsons, Barry and William E. Houchens, both of Charlottesville; his mother, Hortense Zeh Yost, and a sister, Betty Y. Martin, both of Bethesda, and two grandchildren.