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BELL SYSTEM TECHNICAL JOURNAL 



conditions of severe attenuation such as may occur at the very short wave- 

 lengths, the received power commonly varies somewhere between the inverse 

 fourth power and the inverse 16th power of distance. To state it another 

 way, the change in effective range is somewhere between the fourth and 

 the sixteenth root of the change in system performance. The former condi- 





10 IS 20 25 30 



LOSS IN SYSTEM PERFORMANCE db 



Fig. 4 — Effect of reduction in system performance on radar range. 



tion might hold for high angle plane-to-ship search in clear weather, the 

 latter for ship-to-ship search in fog. The loss of range resulting from a given 

 degradation of system performance is shown for 4th, 8th and 16th root laws 

 by the curves of Fig. 4. Whatever the propagation law, reduction in per- 

 formance always means loss of range. 



Field sur\^eys have shown that when test equipment is not available or 

 not used, radars in the field are likely to give no more than ^ to j of the 

 maximum range of which they are capable. Hence it is necessary to know 



