256 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1953 



A Broad-Band Interdigital Circuit for Use in Traveling-Wave-Type 

 Amplifiers. R. C. Fletcher^ I.R.E., Proc., 40, pp. 951-958, August, 

 1952. 



Because of its high power-handling capacity, the interdigital circuit has been 

 considered for use in traveUng-wave-type amplifiers. An analysis is presented here 

 which indicates that this type of circuit can be arranged to give constant phase 

 velocity over a wide bandwidth (30 per cent), as required to give constant gain. 

 The analysis is qualitatively checked experimentally. The impedance parameter 

 (proportional to the cube of the gain in db) is approximately the same as the 

 flattened helix (such as has been used for the magnetron amphfier) and about 

 one-third that of the conventional circular heUx. 



Copper as an Acceptor Element in Germanium. C. S. Fuller^ and J. 

 D. Struthersi. Phys. Rev., 87, pp. 526-527, August 1, 1952. 



Properties of Thermally Produced Acceptors in Germanium. C. S. 

 Fuller^, H. C. Theuerer^ and W. Van Roosbroeck^ Phys. Rev., 85, 

 pp: 678-679, February 15, 1952. 



Initial Permeability and Related Losses in Ferrites. J. K. Galt^ Ceramic 

 Age, 60, pp. 29-33, August, 1952. 



Three-Phase Power From Single-Phase Source. A. L. Holcomb^, 

 S.M.P.T.E., JL, 59, pp. 32-39, July, 1952. 



Described is the development of a nonrotating device for the conversion of 

 single-phase 115-volt power to a three-phase 230-volt form for the synchronous 

 operation of cameras, sound recorders and other film puUing mechanisms asso- 

 ciated with production of motion pictures. 



Dominant Wave Transmission Characteristics of a Multimode Round 

 Waveguide. A. P. Kinqi. I.R.E., Proc, 40, pp. 966-969, August, 1952. 



This paper presents some dominant wave transmission characteristics of 

 multimode round waveguide lines in the 4-kmc range of frequencies. The use of 

 such waveguide lines offers the advantages of lower transmsision losses than ob- 

 tainable with single-mode rectangular waveguide, and relative ease of making 

 good joints. Possible mode conversion effects, including dominant mode eUiptical 

 polarization, have been examined and found to be innocuous. As a result, cross- 

 polarized dominant waves can be used to provide two reasonably independent 

 signahng channels at the same frequency in one pipe. The experimental results 

 obtained with a straight line 2.812-inch inside diameter and length of 150 feet 

 are given. 



Superconductivity in the Cohalt-Silicon System. B. T. Matthias^ Letter 

 to the Editor. Phys. Rev., 87, p. 380, July 15, 1952. 



* Bell Telephone Laboratories 



• Westrex 



