Page:Electronics Technician - Volume 7 - Antennas and Wave Propagation - NAVEDTRA 14092.pdf/54

 The elevation antenna, AS—1669/SPN-35, is a truncated paraboloid-type reflector with a dual-channel feedhorn and a polarizer assembly providing monopulse-type radiation and reception of X-band rf pulses. The horizontal shape of the laminated fiberglass reflector is cosecanted. The dual-channel feedhorn and polarizer are fixed in circular polarization by an external grid device. The elevation antenna is stabilized-yoke mounted on the elevation drive assembly adjacent to the azimuth antenna. The elevation drive provides the required motion for the elevation antenna and locks electrically with the search drive when the radar set operates in the precision mode.

The radar operates in three modes, final, surveillance, and simultaneous, with each antenna acting independently. In the final (precision) mode, the azimuth antenna scans a 30-degree sector (60-degree sector optional) while the elevation antenna scans a 10-degree sector (35-degree sector optional). In the surveillance mode the azimuth antenna rotates through the full 360-degree search pattern at 16 rpm

while the elevation antenna scans a 10-degree sector. In the simultaneous mode, the azimuth antenna rotates through the full 360-degrees search pattern in 60-degree increments while the elevation antenna scans a 10-degree sector. The data rate in this mode is approximately 16 azimuth sweeps and 24 elevation sweeps every 60 seconds.

The antenna pedestal control stabilizes the azimuth and elevation antennas for plus or minus 3 degrees of pitch and plus or minus 10 degrees of roll.

OE-120 UPX IDENTIFICATION FRIEND OR FOE

The OE-120 UPX Identification antenna system transmits binary coded RF interrogation pulses and receives binary coded RF replies from interrogated aircraft and ship transponders.

The antenna group consists of the AS-3 134/UPX, the CV-3372/UPX, and the C-10063/UPX. The AS-3134/UPX elements are mounted around a

Figure 2-51.—0E-120 UPX Identification antenna system. 2-32