ULTRA-SHORT-WAVE RADIO TELEPHONE SYSTEM 541 



at the other end of the circuit, of 12 db over a simple half-wave element 

 with the same power input, at the same mean height. This type of 

 antenna was used as it gave the highest gain and directivity which 

 could be conveniently mounted on a single pole. High directivity was 

 desirable not only as a means of increasing the received signal but also 

 to exclude automobile ignition and other noises originating near the 

 receiving stations. The transmitters and receivers are mounted on the 

 poles with their respective antennas. 



Daily observations of the circuit loss have not shown variations 

 greater than ± 4 db from the normal value. Noise from local thunder 

 storms has never prevented the circuit from being utilized in the 

 normal manner. The several months of trafihc operation to which the 

 circuit has been subjected have disclosed no important technical 

 difficulties with this type of system. It has been found that the radio 

 apparatus can remain in operation over periods of several weeks with- 

 out attention or adjustment. 



