Figure 5. — Automatic direction finding antenna (loops) and data acquisition antenna (whip) attached 

 to the belly of a U.S. Navy S-2 tracker aircraft. (Photo courtesy of J. S. Leatherwood.) 



sisted of a solid fiberglass tapered rod 

 onto which was wound a conductor 

 and loading coil. An aluminum tip 

 served both as a seawater contact and 

 as a section whose length could be 

 trimmed tor peak field strength. A 

 proprietars coating protected the con- 

 ductor and coil from seawater. The 

 antenna was entirely successful on 

 Delphiinis species (Evans, 1971). but 

 problems were encountered when a 

 similar design was used on captive 

 whales such as pilot whales and killer 

 whales. The captive whales invariably 

 broke the antennas by rubbing on 

 structures or boats and in the instance 

 of the release of a pilot whale into the 

 wild, the antenna was broken by sea- 

 weed. Subsequently, a spring-wire 

 antenna was designed which could be 

 severely bent without catastrophic 

 damage and has been used success- 

 fully on the aforementioned whales 

 (Martin. Evans, and Bowers. 1971). 

 This type of antenna was used on the 

 gray whale pack. Subsequent simula- 

 tions of various types of damage to 

 this antenna indicate that modifica- 

 tions would be in order before em- 

 ploying this type of antenna again. 

 Specifically, the arrangement of the 

 spring at the base should be changed 

 to allow the antenna to be bent double 

 against the transmitter case without 

 damage. The antenna should be length- 

 ened somewhat to reduce the variation 

 in impedance for a given variation in 

 the relative position of the ground 

 plane (sea surface) and the loading 

 coil should be fully encapsulated in 

 the nonmetallic antenna's structure to 

 completely eliminate the abrasion 

 damage potential. 



Data Receiving System 



The data receiving and recording 

 system illustrated in Figure 4 was 

 originally tested on board the NUC 

 RV Cape. Subsequent to the initial 

 tracking and data acquisition attempts 



following the release of the whale on 

 13 March 1972. the system was placed 

 on board a U.S. Navy S-2 tracker 

 aircraft. The antenna mounting con- 

 figuration used on this type of aircraft 

 is shown in Figure 5. The whip anten- 

 na is shown in the retracted mode. The 

 loop antenna used in conjunction with 

 the automatic direction finding system 

 is adjustable and was aligned prior to 

 every flight by using a shore-based 

 radio beacon. 



Several relocations of the animal 

 were made using this system. The short 

 transmission range of the damaged 

 transmitter system attached to the 

 whale seriously limited the acquisition 

 of temperature and depth data from 

 the aircraft-mounted system. Tests 



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Figure 6. — California gray whale breaking the 

 the back. The normal sequence of a blow is 

 note exposure of the dorsal ridge. (Photo courtesy 



surface exposing only the head and fore-part of 

 shown right to left at the bottom of the figure, 

 of J. S. Leatherwood.) 



55 



