Development of Silicon Crystal Rectifiers for Microwave Radar Receivers

T O THOSE not familiar with the design of microwave radars the extensive war use of recently developed crystal rectifiers1 in radar receiver frequency converters may be surprising. In the renaissance of this once familiar component of early radio receiving sets there have been developments in materials, processes, and structural design leading to vastly improved converters through greater sensitivity, stability, and ruggedness of the rectifier unit. As a result of these developments a series of crystal rectifiers was engineered for production in large quantities to the exacting electrical specifications demanded by advanced microwave techniques and to the mechanical requirements demanded of combat equipment. The work on crystal rectifiers at Bell Telephone Laboratories during the war was a part of an extensive cooperative research and development program on microwave weapons. The Office of Scientific Research and Development, through the Radiation Laboratory at the Massachusetts Institute of Technology, served as the coordinating agency for work conducted at various university, government, and industrial laboratories in this country and as a liaison agency with British and other Allied organizations. However, prior to the inception of this cooperative program, basic studies on the use of crystal rectifiers had been conducted in Bell Telephone Laboratories. The series of crystal rectifiers now available may thus be considered to be the outgrowth of work conducted in three distinct periods.