Resonance Loss Properties of Ferrites in 9 KMC Region

The low power level transmission loss at room temperature and at 8.2, 8.9, and 10.1 kmc of thin (nominally 0.010-inch thick) ferrite slabs placed approximately in the plane of circular polarization in rectangular waveguide (0.9 ×0.4 inch id) was measured as a function of applied transverse dc magnetic field. Ferramic A,B,C,D,E,G,H,H-1,I,J,N,O-1,Q,R-1,R-2,R-3, and Ferroxcube 101, 102, 103, 104, 105, 106 were measured, although graphical data are presented here only for some typical cases. The absence of resonance loss in the permanent magnet ferrite material Indox in this frequency range and for internal fields up to 5 kilo-oersteds is noted. Results of measurements on some thicker ferrite slabs and other transverse locations are also presented. The effect of temperature on the loss characteristics of Ferramic G, R-1, and Ferroxcube 104 is shown. Thin-Slab theory is used to compute the effective saturation magnetization, 4πM
₈
, and damping parameter, α, (both defined in the text) of the measured ferrites at room temperature, and these results are presented in tabular form. For the different ferrites it is found that 2.6 kilogauss <4πM
₈
<6.6 kilogauss, and 0.02<α <0.3, for internal dc magnetic fields in the range from about 1 to 2 kilo-oersteds.