Production of Lithium Ferrite Assemblies for Phased Array Radars

摘要

An investigation was made of substitutions of Al, Cr, Ga, In, Ni, and Zn in the lithium titanium ferrite (4 piMs = 1200 gauss). A final composition, Li.7275Ti.61Zn.10Mn.10Ni.05Co.005Fe1.4075O4 was selected, and gave an acceptable temperature dependence of insertion phase. Using this composition, eight 2 Kg powder batches and two 40 Kg powder batches were made. Toroid forming, firing, and evaluation techniques were developed to produce a high remanent reproducible waveguide toroid. Over two hundred waveguide toroids were formed from these 10 powder batches in a series of firings. Particular attention was paid to the type of firing cycle and kiln location required to produce a straight toroid. Two techniques, pin drop and ultrasonic measurement, were evolved to determine toroid straightness. The ultrasonic technique shows more promise and was used to monitor the phase shifting wall thickness in a large portion of the waveguide toroids which had been through final machining. Insertion phase temperature measurements on two toroids made from the large powder batches gave results that are competitive with garnet materials. (Author)