Method for measuring complex permeability at radio frequencies
1.National Bureau of Standards, , “High‐frequency calibration of magnetic materials,” Tech. News Bull. NBS 36, 158 (October 1952).
2.G. A. Kelsall, “Permeameter for alternating current measurements at small magnetizing forces,” J. Opt. Soc. Am. 8, 329 (1924).
3.P. H. Haas, “A radio‐frequency permeameter,” J. Res. NBS 51, 221 (1953).
4.A. L. Rasmussen, A. W. Enfield, and A. E. Hess, “Advances in the design and application of the radio‐frequency permeameter,” J. Res. NBS 56, 261 (1956).
5.W. J. Polydoroff, High‐Frequency Magnetic Materials (Wiley, New York, 1960), p. 50.
6.C. A. Hoer and A. L. Rasmussen, “Equations for the radiofrequency magnetic permeameter,” J. Res. NBS 67C, 69 (1963).
7.R. D. Harrington, “Cavity techniques for permeability measurements in the VHF region,” in Electronic Components Conference Proceedings 6 (AIEE and IRE, Los Angeles, 1955), pp. 27–29.
8.The variable‐length coaxial line may be modified for use as a half‐wave resonant cavity at frequencies near 100 MHz. See Ref. 7 and C. A. Hoer and R. D. Harrington, “Parallel reversible permeability measurement techniques from 50 kc/s to 3 Gc/s,” J. Res. NBS 67C, 259 (1963).
9.A. L. Rasmussen and R. C. Powell, “A low‐impedance Maxwell bridge for measuring toroidal magnetic materials from 1 kc to l00 kc,” Proc. IRE 50, 2505 (1962).
10.D. J. Epstein, “Permeability,” in Dielectric Materials and Applications, edited by A. R. von Hippel (Technology Press MIT, Cambridge, and Wiley, New York, 1954), Chap. II (B), pp. 130–132.
11.P. A. Miles, W. B. Westphal, and A. R. von Hippel, “Dielectric spectroscopy of ferromagnetic semiconductors,” Rev. Mod. Phys. 29, 279 (1957).
12.B. E. Mulhall, “The measurement of magnetic permeability at radio frequencies,” Philips Res. Rep. 19, 78 (1964).
13.H. E. Bussey, “Measurement of rf properties of materials, a survey,” Proc. IEEE 55, 1046 (1967);
13.H. E. Bussey, 56, 729 (1968)., Proc. IEEE
14.Hewlett‐Packard Impedance Analyzer, model 4194A (100 Hz‐40 MHz), with 14‐mm GR‐900 precision terminal adapter, part number 16389A. Also used, as alternate instruments, were an LF Impedance Analyzer, model 4192A (5 Hz‐13 MHz) and an RF Impedance Analyzer, model 4191A (1–1000 MHz). These two analyzers need a computer for effective operation. The latter requires a type‐QAP7 connector (electrical length 5.29 cm), converting 7‐mm APC‐7 to 14‐mm GR‐900 connector, instead of a terminal adapter.
15.H. E. Bussey, National Bureau of Standards, Boulder, CO, used a GR‐900 connector with Maxwell and Schering bridges for toroid permeability measurements in 1969.
16.R. F. M. Thornley, Storage Technology Corporation, Louisville, CO (personal communication, 1986).
17.V. Cagan and M. Guyot, “Fast and convenient technique for broadband measurements of the complex initial permeability offerrimagnets,” IEEE Trans. Magn. MAG‐20, 1732 (1984).
18.Convenient demountable coils are described in R. D. Harrington and A. L. Rasmussen, “Magnetic core permeability measurement techniques,” in Magnetic Core Conference Proceedings 7 (Magnetic Powder Core Association, New York, 1965), pp. 11–24. Contact resistance may be a problem with these coils.
19.The initial permeability may depend on the method of demagnetization. See G. W. Rathenau and J. F. Fast, “Initial permeabilities of sintered ferrites,” Physica 21, 964 (1955). According to these authors, “the largest values [of permeability] are apparently obtained if the directions of measurement and demagnetization coincide.” When the directions do not coincide, their data show a decrease in permeability of 10% in a Ni‐Zn ferrite.
20.S. Ramo, J. R. Whinnery, and T. Van Duzer, Fields and Waves in Communication Electronics (Wiley, New York, 1965), p. 304.
21.R. I. Sarbacher and W. A. Edson, Hyper and Ultrahigh Frequency Engineering (Wiley, New York, 1943), p. 282. Their Eq. 7.172 for impedance in terms of complex permeability, may be separated into real and imaginary components.
22.A. L. Rasmussen and C. M. Allred, “An admittance meter technique to measure the complex permeability at VHF,” J. Res. NBS 72C, 81 (1968).
23.A. L. Rasmussen and A. E. Hess, “R‐F permeameter techniques for testing ferrite cores,” Electr. Manuf. 61, 86 (1958).
24.Let Δλ be the change in length of the line required to null the bridge after insertion of the sample. The inner and outer diameters of the line are A and B. The change in inductance corresponding to δλ is From Eqs. (4)‐(6), In measuring, defined in Eq. (11), we determine by rebalancing the bridge after the line has been shortened and the sample removed. The variable‐length line is not a primary standard for
25.The azimuthal magnetic field strength as a function of current l and radial distance r in the GR‐900 coaxial connector is For it ranges from 0.4 A/m (6 mOc) to 1 A/m (13 mOc), the same as the radial variation in field in a wire‐wound toroid. The average magnetic field strength in the connector, obtained by integration, is I where A and B are the inner and outer diameters of the connector.
26.H. E. Bussey and R. W. Beatty, “Higher mode resonances of dielectric support beads in coaxial lines,” National Bureau of Standards, Boulder, CO, 1966 (unpublished).
27.The criterion is tan where λ is the wavelength in free space. See, for example, D. Polder, “Ferrite materials,” Proc. Inst. Electr. Eng. (London) 97, Part II, 246 (1950).
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Article metrics loading...
Full text loading...
Most read this month
Most cited this month