646 BELL SYSTEM TECHNICAL JOURNAL 



to receive simultaneously a number of radio signals on different 

 frequencies. Each one of these receivers with phase shifters will 

 provide its own directivity pattern and may be adjusted independently 

 of the others. 



A Musa system has been constructed for transoceanic reception on 

 short waves at Manahawken, New Jersey, and is now in operation. 

 In this system 16 rhombic antennas are placed in a row approximately 

 a mile and a half long. 



The radio terminals for all services have not attained standardized 

 final forms but are in a slow state of flux as better circuits and methods 

 for handling existing problems are devised. The circuits and devices 

 indicated in the figures in principle or in detail are not the only ones 

 that have been tried or used, but represent steps that at one time or 

 another were considered to be advancements suitable to be put into 

 use while the attentions of the development engineers were directed 

 toward more pressing problems. These various devices have aug- 

 mented the reliability of radio circuits enormously. Distances covered 

 have been enlarged. To accomplish similar results by power increase 

 alone would have in most cases rendered it uneconomic to construct 

 and operate the radio systems. In each case peculiarities either in 

 speech, in radio circuits, or in static and noise characteristics are taken 

 advantage of in making a design to aid the signal and reduce the 

 effect of noise. It is believed that the limit has not been reached but 

 that further improvements and other devices will in due time give 

 increased reliability. 



References 



1. "The Vodas," S. B. Wright, Electrical Engineering, August 1937, or Bell System 



Technical Journal, October 1937. 



2. "A Vogad for Radiotelephone Circuits," S. B. Wright, S. Doha and A. C. 



Dickieson, I.R.E. Proceedings, April 1939. 



3. "A Radio Telephone System for Harbor and Coastal Service," C. N. Anderson 



and H. M. Pruden, I.R.E. Proceedings, April 1939. 



4. "The Compandor, an Aid Against Static in Radio Telephony," R. C. Mathes 



and S. B. Wright, Electrical Engineering, June 1934, and Bell System Technical 

 Journal, July 1934. 



5. "A Short Wave Single Sideband Radio Telephone System," A. A. Oswald, 



I.R.E. Proceedings, December 1938. 



6. "Theoretical and Practical Aspects of Directional Transmitting Systems," E. J. 



Sterba, I.R.E. Proceedings, July 1931. 



7. "Transoceanic Telephone Service," A. A. Oswald, Bell System Technical Journal, 



vol. IX, p. 270. 



8. "Developments in Short Wave Antennas," E. Bruce, I.R.E. Proceedings, August 



1931, and "Horizontal Rhombic Antennas," E. Bruce, A. C. Beck and L. R. 

 Lowry, I.R.E. Proceedings, January 1935. 



9. "An Unattended Ultra-Short-Wave Radiotelephone System," N. F. Schlaack 



and F. A. Polkinghorn, I.R.E. Proceedings, November 1935. 



10. "The Wave Antenna," H. H. Beverage, C. W. Rice and E. W. Kellog, Trans. 



A.I.E.E., vol. 42, p. 215, 1923. 



11. "A Multiple Unit Steerable Antenna for Short-Wave Reception," H. T. Friis 



and C. B. Feldman, I.R.E. Proceedings, July 1937. 



