Behavior of Sea and Ice to Frequency and Polarization 



One of the subordinate objectives of this program was to evaluate the 

 various characteristics of radar systems. Below the subjects of optimum 

 frequency and polarization are treated by a theoretical analysis based on 

 Fresnel's original equations in their complex form. The reflection co- 

 efficient of a surface exhibiting conductivity is complex and as thoroughly 

 presented by McPetrie [22~\, the coefficient may be conveniently repre- 

 sented by a phase component A" and an inquadrature component K' 

 where the reflection coefficient R takes the form (K-\-jK'). Recalling 

 equation (11): 



e c = e r -jti = e r - 2j— = (n-./'f) 2 ( 1 1 ) 



it is apparent that the reflection coefficient, being a function of the com- 

 plex dielectric, is a function of the conductivity, frequency, and angle of 

 incidence. This parameter is also a function of the polarization and it 

 was therefore necessary to perform the tedious computations in order to 

 accurately determine the relation of frequency and polarization to the 

 optimum ice detecting characteristics. Computations based on the equa- 

 tions given below were made for S- and X-band frequencies, vertical and 

 horizontal polarizations and angles of 0°, 20°, 40°, 50°, 60°, 70°, 80°, 82°, 

 83.5°, 84°, 8()°, 88°, and 90° for both pure ice and sea water, and from the 

 best known values of the complex dielectric constants for the radiation 

 considered. McPetrie [_22~\ has derived from the original Fresnel equations 

 the following relations for the reflection coefficient. If the reflection co- 

 efficient for horizontally polarized waves is designated (A'/,+,/AY), the 

 values for these components are given by: 



cos 2 0- (c 2 +(P) 

 K k = 



K h ' 



cos 2 0+(r-+r/-) +2c(cos0) 



-2d(cos0) 

 cos 2 0+ (c 2 +d 2 ) +2c(cos0) 



in which 6 is the electromagnetic angle of incidence (0 = for normal 

 incidence) and r and d are given by: 



d 



-4 



where e, and e r are the imaginary and real parts of the dielectric constant. 

 For the case of radiation polarized with the electric field in the plane of 



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