406 BELL SYSTEM TECHNICAL JOURNAL 



The corresponding value of Q is 



The values of (3"max and /j," depend on the value of d chosen. For a 

 desired value of Q, (11) can be solved for fx", and (10) for the corre- 

 sponding diameter. 



In any case, the ideal wire size has a cross-sectional area of conductor 

 equal to 



^/^ 



OASsd^ -xj- J cm-. 



It is usually desirable to subdivide the wire into insulated strands to 

 minimize eddy current losses in the coil winding. 



References 



'Commercial Loading of Telephone Circuits in the Bell System," B. Gherardi, 



Trans. A.LE.E., v. 30, 1911, p. 1743. 

 ' Development and Application of Loading for Telephone Circuits," T. Shaw and 



W. Fondiller, Jour. A.LE.E., v. 45, 1926, p. 253; B.S.T.J., v. 5, 1926, p. 221. 

 'Magnetic Properties of Compressed Powdered Iron," B. Speed and G. W. El- 

 men, Trans. A.LE.E., v. 40, 1921, p. 596. 

 'Compressed Powdered Permalloy Manufacture and Magnetic Properties," 



W. J. Shackelton and L G. Barber, Trans. AJ.E.E., v. 47, 1928, p. 429. 

 5. A. F. Bandur, U. S. Patent 1,673,790, June 19, 1928. 



'Pupinspulen niit Kernen aus Isoperm-Blech oder -Band," H. Jordan, T. Volk 



and R. Goldschmidt, Europaischer Fernsprechdienst v. 31, 1933, p. 8. 

 'Permalloy, -an Alloy of Remarkable Magnetic Properties," H. D. Arnold and 



G. W. Elmen, Jour. Frank. Inst., v. 195, 1923, p. 621. 

 'Carrier Current Telephony and Telegraphy," E. H. Colpitis and 0. B. Black- 

 well, Trans. A.LE.E., v. 40, 1921, p. 205. 

 ' Radio Extension of the Telephone System to Ships at Sea," H. W. Nichols and 



L. Espenschied, Proc. I.R.E., v. 11, 1923, p. 193; B.S.T.J., v. 2, 1923, p. 141. 

 ' Magnetic Alloys of Iron, Nickel, and Cobalt," G. W. Elmen, Jour. Frank. Inst., 



V. 207, 1929, p. 583; B.S.T.J., v. 8, 1929, p. 435. 

 ' A Survey of Magnetic Materials in Relation to Structure," W. C. Ellis and E. E. 



Schurpacher, B.S.T.J., v. 14, 1935, p. 8. 

 'Statistical Description of the Size Properties of Non-uniform Particulate Sub- 

 stances," T. Hatch and S. Choate, Jour. Frank. Inst., v. 207, 1929, p. 369. 

 'On the Self-induction of Wires," O. Heaviside, Phil. Mag., v. 23, 1887, p. 173. 

 ' Magnetostatik der Massekerne," F. Ollendorf, Arch. f. Elektrotechn, v. 25, 



1931, p. 436. 

 'Iron Powder Compound Cores for Coils," G. W. O. Howe, Wireless Engineer, 



V. 10, 1933, p. 1. 

 ' Magnetic Measurements at Low Flux Densities Using the A-C. Bridge," V. E. 



Legg, B.S.T.J., V. 15, 1936, p. 39. 

 'Harmonic Production in Ferromagnetic Materials at Low Frequencies and Low 



Flux Densities," E. Peterson, B.S.T.J., v. 7, 1928, p. 762. 

 'Hysteresis Effects with Varying Superposed Magnetizing Forces," W. Fondiller 



and W. H. Martin, Trans. A.LE.E., v. 40, 1921, p. 553. 

 'Communication by Carrier in Cable," B. W. Kendall and A. B. Clark, Elec. 



Engg., V. 52, 1933, p. 477; B.S.T.J., v. 12, 1933, p. 251. 

 'Systems for Wide Band Transmission over Coaxial Lines," L. Espenschied 



and M. E. Strieby, Elect. Engg., v. 53, 1934, p. 1371 ; B.S.T.J., v. 13, 1934, p. 654. 

 'The Evolution of the Crystal Wave Filter," O. E. Buckley, Jour. Appl. Phvs., 



V. 8, 1937, p. 40; Bell Tel. Quarterly, v. 16, 1937, p. 25. 

 'An Improved Three-Channel Carrier Telephone System," J. T. O'Leary, E. C. 



Blessing and J. W. Beyer, B.S.T.J., v. 18, 1939, p. 49. 



