WIDEBAND MAGNETOELASTIC FREQUENCY SELECTIVE LIMITER FOR VHF.
Interim rept. 1 Jan-1 Jul 68,
BOEING CO SEATTLE WA
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The first six months progress is summarized for the construction of a frequency-selective limiter using parametrically generated subharmonic magnetoelastic modes in ferrimagnetic material. The choice of the optimum material is found to involve consideration of the effects of saturation magnetization, anisotropy, magnetoelastic coupling, and spin wave linewidth. The anisotropy is found to be undesirable when operating of VHF due to desaturation effects and a reduction in mode density caused by the interaction of the anisotropy-contributed and dipolar-contributed ellipticities. Spin wave saturation is found to restrict the dynamic range rather than linear circuit leakthrough. The threshold level is found to be highly dependent on the fill factor of the circuit as well as material parameters. The optimum orientations of the material in the applied bias magnetic field were found to depend on saturation magnetization and anisotropy. The test results have been obtained using doped Yttrium Iron Garnet oriented in the 100 direction. The minimum thresholds have been on the order O dBm, and dynamic ranges of more than 15 dB have been measured. Selectivities corresponding to Q values of 1,000 to 100,000 are easily obtainable. Author
- Electrical and Electronic Equipment