138 



REFLECTION COEFFICIENTS 



o 



UJ 



-I 



FLIGHTS FROM 

 _ 11/22/43 TO 12/30/43 o o 



,1 2 3 4 5 6 7 



GRAZING ANGLES IN DEGREES 



Figure 2. Reflection coefficient, vertical polarization, versus grazing angle. Sea water. Wavelength — S band. 



shows values greater than 0.9 up to 3 degrees. On 

 three flights made with vertical polarization the points 

 have fallen just slightly ahove the theoretical curve. 

 It is planned to carry on simultaneous measure- 

 ments of X- and S-band values to determine the values 

 to be expected on X band and to prove or disprove the 

 correlation suggested above. 



92 EARTH CONSTANTS IN 

 THE MICROWAVE RANGE" 



'•^•^ Reflection Coefficients 



In writing a summary of the latest results, it was 

 thought that the following grouping of the data 

 would be useful. 



1. Determination of the electrical constants of the 

 ground, sea, and fresh water. 



3. Study of ground and sea reflections under condi- 

 tions encountered in actual operations. 



3. Irregular reflections or scattering. 



••By L. Goldstein, Columbia University Wave Propagation 

 Group. 



Elkctrical Constants of the Ground, 

 Sea, and Fresh Water 



To obtain reliable data on the reflection coefficient, 

 dielectric constant, and conductivity of the ground 

 and also of fresh and sea water, a series of radio ex- 

 periments were performed^'^ which gave results that 

 compared fairly well with those obtained in labora- 

 tory experiments. The experimental conditions were 

 relatively well defined and the physical characteristics 

 of the ground or water derived from these experiments 

 appear to be highly reliable. The wavelengths of the 

 radiation used in these experiments lie in the S band 

 at 9 and 10 cm. 



In the experiments with 9-cm waves, ^■- the nature 

 of the reflecting surface was prepared beforehand and 

 its humidity, occasionally, well controlled. Similarly, 

 with vegetation on the ground, the reflection could be 

 measured with different heights of the turf which was 

 grown on the grounds reserved for the measurements. 



The conditions of the ground in the experiments 

 with 10-cm waves were somewhat less well defined. 



