74 



BELL SYSTEM TECHNICAL JOURNAL 



that proper phases may often be most readily accomplished with 

 intervals of either 34 wave-length or }4 wave-length, have led to a 

 rather general adoption of these closer spacings. 



In Fig. 9, approximate gain ratios from arrays of various lengths 

 have been plotted. These are most applicable for separations in the 

 vicinity of ]i and l4 wave-length. Fig. 10 shows the same data 

 plotted in decibels. Within these limits, it appears that the gain ratio 

 may be expressed by the simple formula G = KL, where L is the array 

 length in wave-lengths and K is approximately 5.6. The result 

 expressed in decibels is G' = 10 \ogiQ{KL). 



Measured Antenna Gains 



The degree to which the gains calculated above are approximated in 

 practice is indicated by the data given in the diagrams of Figs. 11 and 

 12 and in Table I. 



TABLE I 



* This antenna actually consisted of two arrays of four couplets each spaced 

 laterally by one wave-length. The resultant diagram of such an array is for all 

 practical purposes the same as that produced by a continuous array of nine couplets. 



Fig, 11 shows a calculated diagram corresponding to certain 

 receiving arrays used in the transatlantic telephone service between 

 America and England. Several points are plotted on this diagram 

 which correspond to the relative strengths of signals received at vari- 

 ous angles. These points were obtained by observing the relative 

 received signal voltage, measured on a standard field-strength measur- 

 ing set connected to the array as an electric oscillator of constant 

 amplitude was carried around the array at a distance of perhaps 20 

 wave-lengths. The plotted data correspond to the case where the 



