286 BELL S YS TEM TECH NIC A L JO URN A L 



For several years when pressure was high the effort was intense; at times 

 feverish. Judging by miUtary results it was highly effective. Some of the 

 material results of this effort are described in the following pages. 



14. Naval Shipborne Radar Antennas 



14.1 The SE Auleiiiia'° 



Very early in the war, the Navy requested the design of a simple search 

 radar s3-stem for small vessels, to be manufactured as quickly as possible 

 in order to till the gap between design and production of the more complex- 

 search systems then in {process of develo])ment. The proposed system was 

 to be small and simple, to permit its use on vessels which otherwise would 

 be unable to carry radar equipment because of size or power supply capabil- 

 ity. This class of vessel included PT boats and landing craft. 



The antenna designed for the SE system is housed as shown in Fig. 40. 

 It was adapted for mounting on the top or side of a small ship's mast, and 

 is rotated in azimuth by a mechanical drive, hand operated. The para- 

 boloid reflector is 42 inches wide, 20 inches high, and is illuminated by a 

 circular aperture 2.9 inches in diameter. In the interests of simplicity, the 

 polarization of the radiated beam was permitted to vary with rotation of 

 the antenna. 



The SE antenna was operated at 9.8 cm, and fed by 1^x3 rectangular 

 waveguide. At the antenna base, a taper section converted from the 

 rectangular waveguide to 3" round guide, through a rotating joint directly 

 to the feed opening. 



Characteristics of the SE antenna are given below: 



Wavelength 9.7 to 10.3 cm 



Reflector 42" W x 20" H 



Gain 25 db 



Horizontal Beam Width 6° 



Vertical Beam Width 12°, varj'ing somewhat with polarization 



Standing Wave 9.7tolO.Ocm 4.0 db 



10.0 to 10.3 cm 6.0 db 



14.2 The SL Radar Antenna^' 



The SL radar is a simple marine search radar developed by Bell Tele- 

 phone Laboratories for the Bureau of Ships. During the war, over 

 1000 of these radars were produced by the Western Electric Company and 

 installed on Navy vessels of various categories. The principal tield for 

 installation was destroyer escort craft ("DE"s). Figure 41 shows an SL 

 antenna installation al)oard a DE. 'J'he antenna is covered, for wind and 



" Written by R. J. Phillips. 

 " Written by H. T. Budenbom. 



