The AFMS-1018/URC Antenna is a broadband omni-directional UHF ground-to-air communications antenna. It is a collinear array of two cylindrical parallel-fed dipole elements. The non-resonant dipoles provide broadband coverage and a horizontal pattern that is omni-directional within +/- 1.0 dB. The lower half power point of the vertically polarized radiation pattern falls on or slightly below the horizon. Pattern tilt is accomplished by feeding the dipoles in such a manner that the upper dipole lags the lower dipole in phase by a few degrees.
The vertical propagation upward is required to fill the cone of silence. The upper dipole is altered to provide both horizontal and vertical components, thus producing the required upward propagation. The dipole elements and internal transmission line are enclosed in a polyester fiberglass mast. This antenna may be used with any UHF transmitting and/or receiving set designed to operate within its frequency range and RF power handling limitations.
Installation: The antenna assembly mounting flange has eight 7/8 inch diameter bolt holes on an 11-3/4 inch bolt circle. The antenna may be installed to the ship's structure by a suitable mounting plate having matching bolt holes. The mounting plate must have a center hole to accommodate the antenna transmission line.
Considerations: The location for the AS-1018/URC Antenna onboard ship or mounted to a tower should be selected to provide maximum unobstructed coverage within the physical constraints of the mounting structure. UHF propagation is generally line-of-sight and antennas that are masked by surrounding structures produce limited coverage in azimuth and/or elevation. |
Height
|
72 - 3/8 inches
|
Diameter
|
13 - 1/2 inches
|
Weight
|
50 lbs
|
Operating Temperature
|
-32 C to +52 C
|
Frequency Range
|
225 to 400 MHz
|
Input Impedance
|
50 ohms (nominal)
|
VSWR
|
> 2:1 over freq
range
|
Polarization
|
Vertical
|
RF Power Rating
|
20 kW (average)
|
Power Requirement
|
None
|
Feed Type
|
Unbalanced, coaxial
cable
|
AF1018/URC Antenna Radiation Patterns and VSWR Report
(see important specifications at next tab)
