36 



TRANSMISSION EXPERIMENTS AT ANTIGUA, WEST INDIES 



niitting end wore cliiiiiged uvwy v; liuur,s. Ai'ler luakiiig X-band anteiiiias was realiguwl to give maximum 

 several runs using this procedure, results showed that signal return and the change in ship's bearing noted 

 there was no discernible diurnal variation of signal Ijy use of a bearing marker attached to the antenna, 

 strength. Therefore, later runs were made using an- This change was then applied to the remaining an- 

 tenna changes on the transmitting end only at the tennas and the ship's course changed accordingly, 

 conclusion of the run out. Periodic changes of the Additional cheeks on the ship's course were obtained 



20 



40 



60 



80 



100 



120 



140 



160 



EiGURE 3. X-band run out, March 19 to 21, 1945. Signal strengtli.s of various antenna combinations compared 

 to free space level. 



receiving antenna heights were made in order to 

 obtain a complete record of all possible antenna com- 

 binations during each run. 



One of the main difficulties encountered in this 

 type of operation was keeping the ship on the sched- 

 uled course. Deviations from this course were detected 

 by means of sudden drops in signal strength on the 

 X-band receivers. When this occurred, one of the 



by means of the radio direction-finding station. By 

 using this information, it was possible to detect de- 

 viations in the ship's course without losing any part 

 of tlie record. The ranges of these runs extended up 

 to a maximum of 190 miles. Signals were usually 

 detected out to this range on the lowest X-band com- 

 bination and the highest S-band combination of trans- 

 mitting and receiving heights. 



