Dependence of microwave absorbing property on ferrite volume fraction in MnZn ferrite-rubber composites

The effective complex permeability and permittivity spectra in composites with various ferrite volume fractions were calculated using the Bruggeman effective medium theory. The matching conditions for the maximum microwave absorption were determined by substituting the complex permeability and permittivity in the equation for the impedance matching condition. The minimum reflection loss increases from -5 to -40 dB as the ferrite volume fraction increases for /spl nu//sub f/<0.26, where single dip of minimum reflection loss was observed. However, two matching conditions were observed for v/sub f//spl ges/0.26, and two minimum reflection losses shown to be about -40 dB. The results indicate that a microwave absorber with reflection loss of about -40 dB can be designed by controlling the ferrite volume fraction in MnZn ferrite-rubber composites in the frequency range 0.8-12 GHz.

[1]  P. Mongeau,et al.  Basic principles of coaxial launch technology , 1984 .

[2]  Zivan Zabar,et al.  Design and power conditioning for the coil-gun , 1989 .

[3]  Zivan Zabar,et al.  Test results for three prototype models of a linear induction launcher , 1991 .

[4]  D. G. Elliott.  Traveling-wave induction launchers , 1989 .

[5]  H. M. Musal,et al.  Thin-layer electromagnetic absorber design , 1989 .

[6]  Zivan Zabar,et al.  Transient performance of linear induction launchers fed by generators and by capacitor banks , 1991 .

[7]  P. Mongeau,et al.  Multiple stage pulsed induction acceleration , 1984 .

[8]  G. G. Bush,et al.  Validation of mixture equations for dielectric‐magnetic composites , 1988 .

[9]  H. Mark.  Electromagnetic launch technology: the promise and the problems , 1989 .

[10]  K. Churn,et al.  Complex permeability and permittivity and microwave absorption of ferrite-rubber composite at X-band frequencies , 1991 .

[11]  D. A. Tidman,et al.  Electromagnetic Earth-to-space launch , 1989 .

[12]  R. T. Wang,et al.  Scattering of electromagnetic waves by composite spherical particles: experiment and effective medium approximations. , 1988, Applied optics.

[13]  H. M. Musal,et al.  UNIVERSAL DESlGN CHART FOR SPECULAR ABSORBERS , 1990 .

[14]  Jae-Hee Oh,et al.  The microwave absorbing phenomena of ferrite microwave absorbers , 1993 .

[15]  Song-Yop Hahn,et al.  An optimal design of capacitor-driven coilgun , 1994 .

[16]  Zivan Zabar,et al.  Concerning the design of capacitively driven induction coil guns , 1989 .

[17]  H. Kim,et al.  Prediction of Electromagnetic Properties of MnZn Ferrite-Silicone Rubber Composites in Wide Frequency Range , 1996 .

[18]  G. Niklasson,et al.  Optical properties and solar selectivity of coevaporated Co‐Al2O3 composite films , 1984 .

[19]  K. Suetake,et al.  Application of Ferrite to Electromagnetic Wave Absorber and its Characteristics , 1970 .