NOMOCK \IMIIC SOI.l TIONS ion tiii: stwimkd cask 



105 



When .4u < 0°.l, the lower lolics arc so closely 

 packed thai the drawing of a coverage diagram 

 becomes almost impossible. For such cases one 

 should determine, Tor a given decibel value, the lower 

 edge of the lowest lobe. Then, with the aid of the 

 nomograms for b = l />, calculate merely the posi- 

 tions of maxima of the other lobes. 



A work sheet for coverage diagram calculations 

 is shown in Table 2. As an illustrative example we 

 have selected the case in which 



hi = 100 ft,/ mc = 3,000 mc, db = 46 . 



Here db stands for the number of decibels that the 

 power density is below standard, where we have 

 assumed a power of 1 w for the transmitter. The 

 symbol db is defined differently by the MIT group. 

 The correspondence is: 



'/'' < — ► - [db yilT + 49] . 



The value of X, which depends only on db and hi, 

 was obtained from the nomogram of Figure 4 and 

 equals 13.9. The product hj me is, of course, 300,000. 

 The rest of the table was filled out by the methods 

 just described. 



The lobes corresponding to this data were also 

 computed by the MIT method and are shown 

 plotted in dotted lines in Figure 8. In general, these 

 lobes agree completely with our own. In the cases 

 where there is some slight variance, we have also 

 drawn our lobes in heavy lines. Note that the MIT 

 db of 95 corresponds to our db of 46. The nomograms 

 presented herein correspond to a reflection coefficient 

 of — 1 . For any other value they would have to be 

 redrawn. 



