1202 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER, 1953 



is ordinarily accompanied by a 6 to 10 db signal depression over a band 

 of at least several hundred megacycles; (3) fading on frequencies sepa- 

 rated by 160 or more megacycles shows little correlation, but fading on 

 frequencies more closely spaced shows an increasing correlation as the 

 frequency difference is diminished; and (4) frequency diversity offers a 

 practical means of mitigating circuit impairment due to fading, if the 

 transmission can be shifted to a frequency far enough away to minimize 

 correlation with fading on the original frequency. 



ACKNO WLEDGEM ENTS 



The author wishes to acknowledge the important contribution of 

 J. Mallett, who conducted the field tests during which the data were 

 obtained. The field tests and data analysis were under the supervision 

 of R. P. Booth. 



