ABSTRACTS OF TECHNICAL ARTICLES 579 



The locations for the tests were selected to provide a reasonably 

 large range of earth resistivity; also, at one location it was known that 

 the earth structure departed substantially from uniformity. At each 

 of these locations d.-c. transient coupling tests were performed in 

 which transient currents, approximately of the form encountered 

 during faults on d.-c. railway electrifications, were produced in an earth- 

 return circuit, herein referred to as the primary, and measurements 

 were made of the resultant voltages in earth-return circuits, herein 

 called secondary circuits, parallel to and at separations from the 

 primary circuit of from 50 or 60 to 2,000 feet. In addition to the d.-c. 

 transient tests, measurements were made at each location of the steady 

 state a.-c. coupling, in magnitude and phase angle, over a range of 

 frequencies from 20 or 30 cycles to 3,200 cycles. From these a.-c. 

 measurements the transient voltages were computed for a number of 

 cases by evaluating the Fourier integral. The results of the a.-c. 

 coupling tests were useful also in helping to explain, in a general way, 

 the departures of the measured transient voltages from the voltages 

 computed for uniform earth resistivity. 



The measured transient voltages and voltages computed (1) from 

 the a.-c. coupling measurements and (2) on the basis of a uniform 

 earth resistivity, are shown for several representative cases in figures 

 accompanying the paper. 



The Shunt-Excited Antenna.'^ J. F. Morrison and P. H. Smith. 

 The paper describes an arrangement for exciting a vertical broadcast 

 antenna with the base grounded. Construction economy results 

 through the elimination of the base insulator, the tower lighting 

 chokes, and the usual lightning protective devices. The coupling ap- 

 paratus at the antenna end of the transmission line is reduced to an 

 extent which may make unnecessary a separate building for its pro- 

 tection. Greater freedom from interruptions resulting from static 

 discharges is expected. The performance of the design is substan- 

 tially the same as that obtained from the antennas now in general use. 

 The paper describes experimental work done, results obtained, and 

 inferences to be drawn from them. A mathematical appendix is 

 attached. 



Some Fundamental Experiments with Wave Guides.^ G. C. South- 

 worth. This paper describes in considerable detail the early ap- 

 paratus and methods used to verify some of the fundamental properties 

 of wave guides. Cylinders of water about ten inches in diameter and 



*Proc. I.R. £., June 1937. 

 ^Proc. I.R. £., July 1937. 



