412 



BELL SYSTEM TECHNICAL JOURNAL 



where 



/ = frequency in megacycles per second. 

 D = diameter of cavity in inches. 

 L = length of cavity in inches. 

 A = a. constant depending upon the mode. Values of A are given in 



Table II for the lowest 30 modes. Values of Bessel function roots 



are given in Table III for the first 180 modes. 

 B — a. constant depending upon the velocity of electromagnetic waves 



in the dielectric. For air at 25°C and 60% relative humidity, 



B = 0.34799 X 101 

 n = third index defining the mode, i.e., the number of half wavelengths 



along the cylinder axis. 



Table II. — Constants for Use in Computing the Resonant Frequencies of Circular Cvlinders 

 B = 0.34799 X 10^ c = 1.17981X lO^" inches/second 



Value of c is for air at 25°C. and 60*^ relative humidity. D and L in inches; / in 

 megacycles. 



