460 Table 547 



WIRELESS TELEGRAPHY 



Wave Length In Meters, Frequency in periods per second, and Oscillation Constant LC in 

 Microhenries and Microfarads 



The relation between the free wave-length in meters, the frequency in cycles per second, and 

 the capacity-inductance product in microfarads and microhenries are given for circuits between 

 1000 and 10,000 meters. For values between ioo and iooo meters, multiply the columns for n 

 by 10 and move the decimal point of the corresponding LC column two places to the left (divid- 

 ing by 100); for values between 10,000 and ioo.coo, divide the n column by 10 and multiply the 

 LC column by 100. The relation between wave-length and capacity-inductance may be relied 

 upon throughout the table to within one part in 200. 



Example 1 : What is the natural wave-length of a circuit containing a capacity of o.oot micro- 

 farad, and an inductance of 454 microhenries ? The product of tl e inductance and capacity is 

 4^4 X 0.001 =0.454. Find 0.454 under LC ; opposite under meters is 1270 meters, the natural 

 wave-length of the circuit. 



Example 2 : What capacity must be associated with an inductance of 880 microhenries in order 

 to tune the circuit to 5500 meters ? Find opposite 3500 meters the LC value 3.45 ; divide this by 

 8S0, and the quotient, 0.00397, is the desired capacity in microfarads. 



Example 3 : A condenser has the capacity of 0.004 microfarad. What inductance must be placed 

 in series with this condenser in order that the circuit shall have a wave-length of 600 meters ? 

 From the table, the LC value corresponding to 600 meters is 0.101. Divide this by 0.004, die 

 capacity of the condenser, and the desired inductance is 25.2 microhenries. 



Adapted from table prepared by Greenleaf W. Picard ; copyright by Wireless Specialty Apparatus Company, New 

 York. Computed on basis of 300,000 kilometers per second for the velocity of propagation of electromagnetic waves. 



Smithsonian Tables. 



