INTRODUCTION 



51 



Figure 3.2. Differential geometry used in the derivation of the effective-earth' s-radius- 



model atmosphere. 



The apparent range to a target, Re, as indicated by a radar, is defined as 

 an integrated function of n along the ray path, 



r 



Jo 



Re = I ndR = 



ndh 

 sin d 



(3.4) 



However, the maximum range error {R^ minus the true range) likely to 

 be encountered is only about 200 m, hence the evaluation of (3.4) is not 

 of great importance unless one is dealing with an interferometer or phase- 

 measuring system. 



