H YPER-FREQ UENC Y TRA NS MISSION 



329 



VALUES OF ^ 

 Attenuation, a, in Hollow Conducting Cylinder. 



Multiplv ordinates b\- Ao = -^ \ — tTTrTi to read db per mile. 



(1 1 (T X It)'' 



hor copper, Ao = -r^~ • 



Multiply abscissae by/c = (2.30/(^)10^ to read frequency in megacycles. Here 

 fc = critical frequency of fundamental £-\vave in megacycles, 

 d = inner diameter of cylinder in centimeters, 

 <T = conductivity of cylinder in emu 

 = 6.06 X 10-^' for copper. 



IV. Dielectric Cylindrical Guides 



We shall now pass to the mathematical theory of waves in dielectric 

 "wires" of circular cross-section, immersed in air. We assume that 

 the dielectric is perfect. The field in such a dielectric guide, and in 

 the air outside, can be represented by the same general expressions 

 as in hollow tubes. Thus for the «th harmonic wave, we have 



E, = AnJnO^ip) cos nd, 

 Ez = CnKni^ip) cos nd, 



Hz = BnJnO^ip) sin nd, in the guide, 

 Hz = DnKn0^2P) sin nd, in the air. 



(54) 



The exponential factor g— >2+^"' is implied in these as well as in the 

 subsequent expressions for the field intensities. Another fundamental 

 solution is obtained by changing d into d + 7r/2«. 



The transverse components of E and H are obtainable from E^ and 

 H, by differentiation. For our present purposes we need only E@ and 

 H^; these are 



