| AS-1496/U |
|
| Physical
Dimensions |
|
| Height |
69
- 1/2 inches |
| Width |
31
- 3/8 inches |
| Depth |
40
- 3/8 inches |
| Weight |
100
lbs |
| Operating
Temperature |
-32
C to +65 C |
|
|
| Frequency
Range |
225
to 400 MHz |
| Input
Impedance |
50
ohms (nominal) |
| VSWR |
>
3:1 |
| Polarization |
Vertical |
| RF
Power Rating |
200
watts |
| Power
Requirement |
None |
| Feed
Type |
Unbalanced,
coaxial cable |
| Input
Connector |
Type
N, UG-29B/U |
|
|
Description:
The AS-1496/U and AS-1497/U are used with the PHASOR-90 UHF
system. The antennas are arrays consisting of two circularly
polarized conical spirals spaced one wave length apart at
300 MHz. The AS-1496/U has a right-hand spiral, while the
AS-1497/U has a left-hand spiral; otherwise the two antennas
are identical. The two conical spirals are mounted on a
small ground plane or mounting plate. Each conical spiral is
fed at the apex of the cone through a balun and presents a
nominal impedance of 100 . ohms. When the two conical
spirals are connected in parallel a nominal impedance of 50
ohms is presented to the transmission line. A system
consists of two each AS-1496/U and AS-1497/U antennas and a
power divider. The power divider is a low loss transformer
which divides the power from a single 50 ohm source into
four separate 50 ohm outputs to the antennas.
The PHASOR-90 system was
designed for use on board aircraft carriers for
ship-to-aircraft communications. This system is considered
to be obsolete and is being replaced by AN/SRA-62 Sector
Array.
Installation: The antenna arrays are installed
by bolting the unit to the ships structure through bolt
holes on the ground plane. The antennas are usually
installed on the carrier's island located in such a manner
as to provide unobstructed coverage in all quadrants. The
arrays on adjacent sides of the ship's island must be of
opposite sense, i.e., if the fore and aft arrays are
left-hand circular the port and starboard must be right-hand
circular. The arrays should be free frOm obstruction to the
antennas near field within 20 degrees of the horizon in the
respective quadrant. The lengths of coaxial cable between
the power divider and the four antennas should be
approximately the same length.
Considerations: When installing additional
arrays they should be mutually separated as far as possible
to provide isolation between systems. Additional isolation
can be provided by placing oppositely sensed arrays next to
each other. |
