26 



RESULTS AND RECOMMENDATIONS 



the propagation problem were received from the nu- 

 merous investigating laboratories. These reports were 

 analyzed and the essential information contained 

 was put into forms suitable for the use of operational 

 personnel and distributed to the Services of the 

 United States and the other Allied Nations. Such 

 dissemination usually was in the form of publications 

 by the CUDWR WPG, which issued a total of 34 

 such reports to a large distribution list. These reports 

 and the very much larger number of scientific papers 

 from which they were prepared are listed in the 

 Bibliography. 



42 CRITIQUE 



The greatest handicap to the work of the Committee 

 on Propagation was the delay in recognizing the need 

 for such an organization. In the rush to get elec- 

 tronic equipment that would allow the realization 

 of the many new war inventions, the fact that the 

 tactical use of these equipments depends upon their 

 quantitative performance, which in turn depends 

 upon the transmission medium, was neglected. As a 

 result when this need was finally recognized the few 

 experts in this field were deep in important war work 

 and the committee decided to work with existing 

 laboratories, letting new contracts for specific proj- 

 ects rather than setting up a central laboratory late 

 in the war. The work of the committee should have 

 begun with the conception of the ideas of the new 

 radio systems, radar, loran, VHF (very high fre- 

 quency) communication systems, guided missiles, etc. 

 Then there would have been time to have established 

 a central laboratory for carrying out propagation 

 research and evaluating the performance charac- 

 teristics of equipment. 



4.3 FUTURE PROPAGATION RESEARCH 



During the latter part of 1943, Committee members 

 and liaison officers gave considerable attention to the 

 matter of propagation research which would be desir- 

 able to have continued into the postwar period. 

 Studies were made of the knowledge already obtained 

 with a view to outlining the principal gaps in that 

 knowledge and developing a general program for 

 filling them, which could be carried on by such 

 organizations as the Service laboratories or the 

 Research Board for National Security. The results 



of these studies are given here, divided roughly 

 into suitable categories. 



Propagation Problems 



1. Subnormal propagation through fog and sus- 

 pended water and ice particles. 



2. Modifications of the coverage diagram when 

 the radiation source is located in or below the hori- 

 zontal layer exhibiting nonstandard variations of 

 refractive index with height. 



3. Errors produced in operation of direction 

 finders, navigational equipment, and gunlaying radar 

 by varying factors of tropospheric propagation. 



4. Effects on atmospheric reflection of variations 

 of frequency, pulse rate, pulse length, radiated power, 

 and other variable parameters. 



5. Correlation of variations of horizontal and 

 vertical angle of arrival of radio waves with simul- 

 taneous meteorological measurements and evaluation 

 of resulting variations in propagation characteristics. 



6. Determination of frequencies permitting great- 

 est security under various meteorological conditions. 



7. Measurements of absolute signal strength and 

 characteristics of the transmitted signal. 



8. Determination of atmospheric noise levels in 

 all important regions and the variation with season, 

 frequency, and meteorology. 



9. Phenomena responsible for long distance propa- 

 gation in the 100- to 200-mc region. 



10. Characteristics of propagation in the region 

 between 50 and 500 kc. 



1 1 . Tropospheric propagation measurements over 

 various types of terrain and water surfaces to deter- 

 mine, more accurately, coverage, angle of arrival, 

 reflection, scattering, and absorption over the range 

 in which the refractive index of the troposphere 

 shows significant change. 



12. Further theoretical analysis of propagation 

 phenomena and comparison with observed experi- 

 mental results. 



Meteorological Problems 



1. Particle sizes and distribution for all forms of 

 atmospheric water. 



2. Survey of the Pacific area similar to the German 

 Meteor study of the Atlantic. 



Equipment Problems 



1. Development of improved equipment for measur- 

 ing variations of atmospheric refractive index. 



2. Development of improved equipment for gener- 



