Description: The AS-390/SRC Antenna Assembly is an unbalanced broadband coaxial stub antenna used for transmitting and receiving. It consists of a radiator and ground plane. The ground plane (or counterpoise) consists of eight elements bent downward 37 degrees from the 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. This is determined at time of manufacture and locked during final assembly of the antenna. The antenna may be used with any UHF transmitting and/or receiving equipment designed to operate within its frequency range and RF power handling limitations.
Installation: The base of the antenna assembly is provided with a threaded 3/4″ -14 IPS pipe 1-1/2″ long for use-in mounting the antenna. The antenna may be installed to the ship’s supporting structure, using a matching size pipe and pipe coupling. The support pipe should be welded to the ship’s structure.
Considerations: The location for the AS-390/SRC antenna onboard ship should be selected to provide maximum unobstructed omnidirectional coverage within the physical constraints of the ship’s structure. UHF propagation is generally line-of-sight and antennas that are masked by surrounding structures produce limited coverage in azimuth and/or elevation. The antenna is designed to be sufficiently airtight to maintain a dielectrically stable atmosphere within the antenna. The presence of moisture may be checked by the removal of a pipe plug located on the underside of the counterpoise plate. The antenna should not be located in stack gas drafts or exhausts where the temperatures exceed the operating temperature limitations.
|Operating Temperature||-32 C to +150 C|
|Frequency Range||220 to 400 MHz|
|Input Impedance||50 ohms (nominal)|
|VSWR||> 2:1 over freq range|
|RF Power Rating||200 watts (average)|
|Feed Type||Unbalanced, coaxial cable|
|Input Connector||Type N, special, mates with UG-21B/U|