1122 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 

 LOSSES DUE TO OXYGEN ABSORPTION 



In addition to the losses which result from imperfect conductivity, 

 surface effects, and mode conversions, there is a very appreciable loss 

 due to oxygen absorption when the guide is open to the atmosphere. In 

 a waveguide the loss due to O2 absorption is: 



where 



A is the absorption due to oxygen in the atmosphere 

 = X/Xc 

 = free space wavelength 



= cut-off wavelength 



V 



X 



Xc= ^ = 



k 3.83 -.: ._ 



d = internal diameter of waveguide ^ 



k = Bessel root for TEoi mode = 3.832 

 The loss due to absorption of oxygen which is present in the at- 

 mosphere (at approximately sea level) was obtained from the experi- 

 mental data of D, C. Hogg.^ The added loss produced by the presence 



0.5 



o 

 o 



CO 

 o 



O 



o 



I- 



UJ 



D 

 Q 



(/) 

 W 



o 



_l 



in 

 < 



a. 

 o 



z 



0.4 



0.3 



0.2 



0.1 



5.0 5.2 5.4 5.6 



WAVELENGTH IN MM 



5.8 



Fig. 6 — TEoi transmission loss in waveguides due to oxygen absorption. 



' A. B, Crawford and D. C. Hogg, Measurement of Atmospheric Attenuation 

 at Millimeter Wavelengths, B.S.T.J., 35, pp. 907-917, July, 1956. 



