70, a retired electrical engineer and researcher with the Washington offices of the Aerospace Corp. of Los Angeles, died of emphysema April 14 at his home in Annapolis.

Dr. Hedeman was born in Baltimore. He graduated from the Massachusetts Institute of Technology where he also earned a doctorate in electrical engineering.

During World War II, he worked for the Bendix Corp. and went to England to help develop a radar landing system for the Royal Air Force. He later worked for electronics firms in Texas.

He joined Aerospace in Los Angeles in 1966 and transferred to Washington in 1976. He retired in 1979 and moved to Annapolis. Since then, he had been a consultant with the National Aeronautics and Space Administration and the Defense Department.

Dr. Hedeman was a member of the Institute of Electronics and Electrical Engineers, Sigma Xi, the professional engineering society, and the Annapolitan Club. He also had published many technical papers and held several patents in radar, television and magnetic tape recording technology.

His marriage to the former Elise Thomas ended in divorce.

Survivors include his wife, Jane F., of Annapolis; five children by his first marriage, Walter Jr., of Wappingers Falls, N.Y., William T., of Redlands, Calif., Paul T., of Reston, Elise Conser of Flanders, N.J., and Susan E. Matteis of San Diego; two brothers, William N., of Baltimore, and Dr. John L., of Annapolis; a sister, E. Ruth Hedeman of Clarkston, Mich., and seven grandsons.