To 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.