AVAVECiUIDE A8 A C'U.M.M UXK'ATlOX MKDH M 



J21',) 



very little wall current flowing in the direction of propagation and there- 

 fore approximate tlie low-loss properties of the circular el(>ct ric wave 

 family. Under certain conditions of mode coupling, which will he de- 

 scril)ed at a later point, it is undesirahle for the medium to be able to 

 propagate modes with attenuation coefficients comparable to that of the 

 mode which is used for communication purposes. 



SOME RESULTS OF TRANSMISSION EXPERIMENTS 



Transmission experiments have been conducted on the 500-ft wa\'e- 

 guide line shown in Fig. 9.* Supports for the line were set in concrete 



40 



1.0 

 0.9 

 0.8 

 0.7 

 0.6 



10 

 XIO^ 



20 30 40 50 60 80 100 



FREQUENCY, f, IN MEGACYCLES PER SECOND ^'° 



Fig. 7 — Attenuation versus frequency for a 2" dianieter round waveguide. 



* This is the same line used for the work r('i)ortod in Reference 1. Some of the 

 e.xperiments described in Reference 1 arc ;d.so doscriliod hero in order to furni.sh 

 background for the new material. 



