necessary. The 1!)1 observations received from all types of vessels and 

 competencies of observers were first examined to determine if the estab- 

 lished criteria for usuable data were met. These criteria vary with the type 

 of measurement ; however, basically all accepted reports had the maximum 

 range of detection, and sketch and/or photograph of the maximum range 1 

 aspect appropriately dimensioned. Comments on anticlutter devices were 

 neglected for the most part as the conflicting reports indicated a good 

 deal of subjectivity. An extensive examination of the anticlutter devices 

 documented by radar scope photographs was made by the writer on three 

 different Ice Patrol vessels. The evaluation of the effect of sea return is 

 based on these controlled observations on different types of ice formations 

 under varying sea conditions and on the writers experience with three 

 radars in the Arctic and Antarctic while in the capacity of Combat In- 

 formation Center Officer on the Coast Guard Icebreaker, USCGC West- 

 wind. The photographs or sketches of the 152 accepted targets were en- 

 larged and the physical cross sections determined. The reflected power 

 measurements and maximum range measurements were treated sta- 

 tistically by the method of least squares, and throughout an effort has 

 been made to view the data objectively. 



The following discussion moves from a consideration of the maximum 

 range of iceberg detection to a discussion of iceberg reflectivity, radar 

 propagation over the Grand Banks area, the danger of sea return, and 

 finally an evaluation of anticlutter device effectiveness. The observa- 

 tional results are compared with the theoretical in each case to allow an 

 evaluation of the conclusions. It is hoped that the reader will not be 

 burdened by the presentation of basic concepts which underlie the many 

 disciplines applicable to this study. 



MAXIMUM RANGE OF ICEBERG DETECTION 



Empirical Expression 



The maximum ranges of detection for the 152 targets studied are shown 

 in figure 24. The best fit locus of these observations by least squares 

 analysis is the curve: 



R<os=S.78X10 Vi A (1) 



where R is the maximum range of detection in yards and A is the physical 

 cross-sectional area in square feet illuminated by the radar at maximum 

 range. This fourth power relationship is in remarkable agreement with the 

 theoretical expression for the relation of maximum range to actual area 

 for some geometric shapes as derived from the free space radar equation: 



W = KX\ 



where A' is a function of receiver sensitivity, antenna gain, and trans- 

 mitter power output. Because the characteristics of all the radars used 



55 



