APPLICATION OF WIRE TRANSMISSION TO RADIO 



123 



in the transmitting:; medium, we fmd that for moderate distances, 

 up to 200 miles (320 km.), as plotted in Fig. 2, the wire losses are in 

 general less, and at telephone frequencies very much less, than the 

 radio losses. The low wire attenuation at telephone frequencies is, 

 of course, in keeping with experience and accounts for the economical 

 terminal apparatus which is employed in telephone practice. Like- 

 wise the relatively high losses for radio accounts for the large amplifica- 

 tion at either the sending or receiving end or both, which experience 

 has proven to be necessary. This brings in an interesting side- 



WIRE AND RADIO TRANSMISSION LOSSLS WITH DISTANCE 



1000 



:ooo 



3000 



4000 



5000 



light, namely, that altho in radio the transmission medium is provided 

 by nature, the effective use of this medium is not as economical as 

 might be expected because it requires considerable equipment, ampli- 

 fiers at both ends for overcoming the large attenuations, selective 

 means for dividing-up the frequency range and thereby "multiplex- 

 ing" the ether, and antennas for getting into the medium and out 

 again. 



For the higher frequencies, the wire attenuations increase rela- 

 tively more rapidly than the radio, thus limiting the frequency range 



