318 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1962 



The second incident was another accidental observation, this time 

 by Hyland, a colleague of Taylor and Young. During experiments 

 on high-frequency radio direction finding in June 1930, he detected 

 a severe disturbance of the propagation field by an airplane flymg 

 overhead. Hyland was also an experienced Navy employee, and was 

 sensitive to the potential threat of military aircraft and the need for 

 warning devices against them. The observation again was unrelated 

 to his experiment, but the application was obvious, and he immediately 

 proposed that high-frequency radio be used for aircraft warning. 



On Taylor's recommendation a project was established at the Naval 

 Research Laboratory in January 1931 for "Detection of Enemy Vessels 

 and Aircraft by Radio." Work on this project continued for several 

 years. The "beat" method was employed, in which transmitter and 

 receiver were widely separated and shielded from each other, transmis- 

 sion was CW, and reception observed the fluctuating signals, called 

 "beats," when an airplane flew through the radio propagation field. 

 Detection ranges of 40 miles were obtained in these experiments. 



The required wide separation of transmitter and receiver precluded 

 the use of the beat method on ships and limited its usefulness to the 

 protection of large land areas such as cities and military bases. Since 

 this was exclusively the responsibility of the Army, it was proposed 

 in January 1932 that the Army take over the development for its use 

 in that fmiction. Subsequently, Navy interest in the problem lagged 

 until Young suggested to Taylor that the pulse method be tried. 

 Young's proposal combined for the first time all five elements essential 

 to radar. Ultimately, Taylor accepted the proposal and assigned to 



AUDIO 

 OSCILLATOR 



BUFFER 

 AMPLIFIER 



SYNCHRONIZED 

 SWEEP CIRCUIT 



J- 



RADIO FREQUENCY PULSE 

 RECEIVER 



SYNCHRONIZED 

 RADIO FREQUENCY PULSE 

 TRANSMITTER 



o 



OSCILLOSCOPE 



Figure 1. — Block diagram of radars operated in 1936. The block diagram for the radar 

 tested in December 1934 was similar to this one. 



