Center-Fed Dipole

Center-Fed Dipole The center-fed dipole (fig. 2-27) is designed for use at an average power rating of 100 watts. All major components of the radiating and support structures are aluminum. The central feed section and radiating elements are protected by a laminated fiberglass cover. Center-fed dipole antennas range from 29 to 47 inches in height and have a radiator diameter of up to 3 inches. Coaxial Dipole Figure 2-28 shows two types of coaxial dipoles. The coaxial dipole antenna is designed for use in the uhf range, with an rf power rating of 200 watts. The Figure 2-27.—AS-2809/RC center-fed dipole antenna. AT-150/SRC (fig. 2-28, view A) has vertical radiating elements and a balun arrangement that electrically balances the antenna to ground. Figure 2-28, view B, shows an AS-390/SRC antenna assembly. This antenna is an unbalanced broadband coaxial stub antenna. It consists of a radiator and a ground plane. The ground plane (or counterpoise) consists of eight elements bent downward 37 degrees from horizontal. The lower ends of the elements form points of a circle 23 inches in diameter. The lower section of the radiator assembly contains a stub for adjusting the input impedance of the antenna. The antenna is vertically polarized, with an rf power rating of 200 watts, and a vswr not greater than 2:1. SATELLITE SYSTEMS The Navy Satellite Communication (SATCOM) provides communications System links, via satellites, between designated mobile units and shore sites. These links supply worldwide communica- tions coverage. The following paragraphs describe some of the more common SATCOM antenna systems to which you will be exposed. AS-2815/SRR-1 The AS-2815/SSR-1 fleet broadcast receiving antenna (fig. 2-29) has a fixed 360-degree horizontal pattern with a maximum gain of 4 dB at 90 degrees from the antenna’s horizontal plane. The maximum loss in the antenna’s vertical pattern sector is 2 dB. The vswr is less than 1.5:1, referenced to 50 ohms. This antenna should be positioned to protect it from interference and possible front end burnout from radar and uhf transmitters. ANTENNA GROUPS OE-82B/WSC-1(V) AND OE-82C/WSC-1(V) Designed primarily for shipboard installations, these antenna groups interface with the AN/WSC-3 transceiver. The complete installation consists of an antenna, bandpass amplifier-filter, switching unit, and antenna control (figs. 2-30 and 2-31), Depending on requirements, one or two antennas may be installed to provide a view of the satellite at all times. The antenna assembly is attached to a pedestal that permits 2-16