WIDE-BAND OPEN-WIRE PROGRAM SYSTEM 



355 



the low frequencies being transmitted with much less loss than the 

 high frequencies. Since the program circuits employ the same type 

 of open-wire facilities that is used in the message circuits, three 

 different gauges of wire with either of two pin spacings between 

 wires may be used and the repeater sections may vary in length from 

 60 to 300 miles. This means that the attenuation frequency char- 

 acteristic of a repeater section not only varies with frequency but also 

 varies considerably in magnitude of attenuation depending on gauge 

 of wire and length of repeater section. 



On Fig. 2 are shown three pairs of characteristics which illustrate 

 the loss-frequency characteristics of three lengths of 165-mil, 8-inch 



100 500 1000 



FREQUENCY IN CYCLES PER SECOND 



10,000 



Fig. 2 — Loss of 165-mil. 8-inch spaced pairs when inserted between 600-ohm 



resistances. 



spaced circuits. The lengths chosen for purposes of illustration are 

 100, 200 and 300 miles, respectively. The solid line curves show 

 the insertion loss-frequency characteristics of the circuits for average 

 dry weather conditions when the circuits are connected between 600- 

 ohm resistances. The dashed line curves indicate the wet weather 

 insertion loss characteristics, that is, they indicate the loss-frequency 

 characteristic which might obtain if the lines were very wet for the 

 entire length of a repeater section. 



For the purpose of comparing the attenuation frequency character- 

 istics of the different types of open-wire lines, the curves shown on Fig. 

 3 have been prepared. These characteristics have been plotted so 



