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BELL SYSTEM TECHNICAL JOURNAL 



involved in the data of Table I. One is due to the doubtful magnitude 

 of a correction necessary to account for the various heights at which 

 the arrays were located above the earth and the second is the error of 

 measurement of gain as compared with the reference antenna. These 

 errors are approximately equal and together amount to ± 1 db. 



In order to test further the agreement between measured gains and 

 those calculated from the simple assumptions above, a receiving array 

 was assembled step by step and corresponding measurements made. 

 Certain precautions, such as to maintain impedance matches at points 

 of coupling, were observed. The resulting data were plotted as points 

 in Fig. 12. A smooth curve represents the corresponding calculated 



2 4 6 8 10 12 14 16 le 20 22 24 26 



NUMBER OF COUPLETS 



Fig 12 — Relation of measured to calculated gain of receiving antenna array at 



14,350 kc. 



data. It will be observed that the measured values are consistently 

 higher than those calculated at the lower end of the curve, and in this 

 region the agreement can hardly be regarded as satisfactory. How- 

 ever, limited time prevented a thorough study of the errors of measure- 

 ment. Consequently these limited data may not be regarded as any 

 adequate test of the theory. 



Combinations of Arrays 



It may be shown that two or more similar directive systems may 

 be combined to give a total directive effect, represented by the product 

 of the individual effect, multiplied by the group effect. This principle 

 is partially covered by equation (35) of the mathematical appendix. 



