HANNA: DESIGN OF TRANSMISSION LOSS EXPERIMENTS 



discontinuity at the interface because they have different velocity 

 gradients and it bends the right way to cause a caustic. 



Dr. Hanna: The implication of that is what? 



Mr. Pedersen: Well, that the intensity can be much larger for 

 this one that goes down into the bottom there than that other one. 

 Say, if the original energy that goes into the bottom is less than 

 the reflected ray, you could still get certain convergence regions 

 for that path that goes down next to bottom. 



Dr. Hanna: Are you essentially saying that if I began with an 

 amplitude of A incident on the bottom and ran this path through the 

 problem and back out again — well, let me try to simplify the problem 

 just a little by ignoring the reflected path. 



Let's say there is no reflection at the boundary and the only 

 thing that happens is that this path goes down, gets refracted and 

 comes out again. 



Are you saying, essentially, that if I go to the surface here 

 where the path originates and terminates that I should expect to see 

 a received intensity for this path which may be higher than what 

 corresponds to simply keeping track of spreading loss along that path? 



Mr. Pedersen: There is at least one more path. The point of 

 it is whenever you have one gradient, and then you have another 

 slope discontinuity to a steeper gradient, you always get a caustic, 

 if you increase the angle to a steep enough angle. 



Mr. C. W. Spofford (Office of Naval Research) : Yes, but, Mel, 

 that caustic is occurring way back in range in this problem. John is 

 talking of 5 or 10 degrees, and the caustic was around 25 or 30 degrees. 



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