AUSTIN : RADIOTEI.EGRAPHY 



395 



TABLE I 



Elongated Parallel Wire Antennas — Capacity in Microfarads 



Calculated 



Leads Observed • . 



Antenna Types Observed Est'd minus leads BS formula Eq. (2) 



1. Marconi "L" 0.060 0.007 0.053 0.0542 0.0545 



2. Medium Ship Type .. . 0.0020 0.0006 0.0014 0.00147 0.00151 



3. Portable Ship Type .. . 0.00040 0.00006 0.00034 0.000335 0.000350 



4. Model Marconi "L" ... 0.00028 0.000275 0.000255 



Data for Calculation 



Length 

 m 



I. 1830 



2- 91-5 



3- 25.9 

 4. 18.3 



Breadth 

 m 



160 

 9 15 

 152 

 0.406 



Number of Diam." 



Area 



wires n 



32 

 II 



6 

 6 



mm 

 10 



3 



3 



2.5 



293 



8.38 



39-4 



7-43 



io'» 

 10'^ 



Height 

 m 



104 



49 

 12 

 I 52 



1/b 

 II. 4 

 10 

 17 



45 



** Approximate wire diameter. 



TABLE 2 



Various Antenna Shapes — Capacity in Microfarads 



Antenna Types Observed 



5. Triangle 0.0155 



6. Square 0.0180 



7. Irregular 0.038 



8. Triangle o . 0065 



Leads 

 Est'd 



0.003 



0.003 



0.002 



O.OOI 



Observed Calculated 

 minus leads Eq. (1) 



Area 

 m2 



9. Portable Triangle .. . 0.00084 0.00006 0,00078 



10. Model Triangle 



11. Model Circular Disk 



12. Umbrella 0.016 0.0015 



13. Model Circular Disk 



0.0125 0.0129 5.98 10^ 

 0.0150 0.0136 6.25 10^ 

 0.0360 0.0378 26.8. 10* 

 0.0055 0.0054 I. 156 10^ 

 0.00085 2 .67 10- 

 0.000075 0.000068 1.457 

 0.000135 0.000125 3.56 

 0.0145 0.0147 7.24 10^ 

 0.000053 0.000055 0.933 



Height 

 m 



170 



160 



137 



915 



12 

 0.633 

 0.635 



162 

 0.50 



The chief uncertainty in the observed values of both tables 

 lies in the estimation of the capacity of the downleads, etc. 

 In the case of the models 4, 10, and 13, this was measured along 

 with that due to the measuring instruments and subtracted from 

 the observed values. 



In addition to its importance in radiotelegraphy, equation (i) 

 has a more purely scientific interest, since it appears to represent 

 the capacity of plate condensers in general for all values of plate 

 separation provided one of the plates is grounded. The so-called 

 edge effect is represented by the capacity in space term. The 

 expression if exact for circular plates, should be nearly so for all 



