T-Scanners. Large T-Frame Scanners NEAR-FIELD SCANNERS

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1 Large T-Frame Scanners The AL-4953 and AL-4954 series planar scanners are high-accuracy, large-sized scanners. These scanners are available with scan areas up to 65' x 32'. The position accuracy, resolution and planarity provided by the AL-4953 and AL-4954 scanners are consistent with the requirements of large antennas, low sidelobe Near-Field antenna measurements. The scanners are constructed of an X axis linear slide and a moving tower for the Y axis. The X axis linear slide comes in two widths. The AL series scanners have a track gauge of 1.1m, while the AL-4954 series has a track gauge of 1.8m. The slide is constructed of modular sections, each about 3m long. The modules are tied down to the scanner foundation and leveled as one integral track. The AL-4953 and AL-4954 series planar scanners are constructed from steel. Precision linear bearings are used to ensure straightness over the full length of the X (horizontal) and Y (vertical) travel. The X axis is driven by a rack and pinion drive system which eliminates "jerking" under acceleration, minimizing position errors. The Y axis is also driven via a rack and pinion system. This axis utilizes a counterbalance mechanism to eliminate backlash and protect the measurement probe in the event of a power failure. These units may be aligned to minimize planarity and axis orthogonality errors that can be detrimental to phase measurements in the Near- Field. The Y axis tower moves on the X axis table. It is also built from modular truss units, each about 3m high. The modules are installed vertically and aligned to form one integral track, perpendicular to the X axis. The structure requires special preparation to install absorbing material. A standard probe interface is provided allowing a variety of probes to be affixed via a single adapter or on the optional Z-Roll unit. For the large scanners, the interface with the building is most critical and must be taken into account when designing the Near-Field Measurement System. AL-4951T 13

2 Specifications AL X-Y-V AL X-Y-V Construction Grade Scan Travel X Scan Travel Y Payload Carriage Bending Moment X Speed Steel m 6,9,12,15,18 8,11,14,17,20 ft 19.7, 29.6, 39.5, 49.3, , 36, 46,56, 65.5 m 5, 6, 7 9, 12, 15 ft 16.4, 19.7, , 39, 49 kg lbs m-kg ft-lbs mm/sec in/sec 2 2 mm/sec Y Speed in/sec 5 5 Motor Drive Power X hp 1 1 Motor Drive Power Y hp 1 1 mm x(m)/ x(m)/100 Accuracy (RMS) X in X(ft)/ X(ft)/8355 mm Y(m)/ Y(m)/100 Accuracy (RMS) Y in Y(ft)/ Y(ft)/8355 mm Planarity (RMS) in mm Readout Resolution Rotary Encoder in mm Scan Travel in m/360 Scan Travel in m/360 Readout Resolution Synchro (opt. RS) in Scan Travel in ft/3008 Scan Travel in ft/3008 Repeatability X Repeatability Y Repeatability Z Polarization Positioner (optional) Z Travel Stage (optional) Track Gauge Weight (approx.) AL AL m ft kg 5,000 to 10,000 10,000 to 15,000 lbs 11,000 to 22,000 22,000 to 33,000 14

3 Options?? BR-X Base Riser. Specify x=height, from 4" to 24" in 4" increments?? COR Z-planarity mapping for correction table?? HS High-Speed Option: Enhance the maximum speed of the Y axis to 14 in/sec (360 mm/sec)?? Laser X-Y X-Y Laser Interferometer System?? Laser Z Z Planarity Laser Interferometer System?? MM Metric Interface?? PRP-1 Absorber preparation plates and hardware for mounting absorber on scanner face. Applies to AL-4951 Series scanners. Absorbers sold separately.?? PRP-2 Absorber preparation plates and hardware for mounting absorber on scanner face. Applies to AL-4952 Series scanners. Absorbers sold separately.?? RF18 RF cable path option, DC-18 GHz. Scanner base to probe region?? RF40 RF cable path option, DC-40 GHz. Scanner base to probe region?? SN002 Replace incremental rotary encoder with synchro in X and Y axes?? WH4 Wheels (AL V only).?? ZR10 Motorized Z-Roll Unit (10 lbs, 10 ft-lb) Includes wiring?? ZR50 Motorized Z-Roll Unit (50 lbs, 100 ft-lb) Includes wiring?? ZRW Wiring only for motorized Z-Roll unit. Recommended if Z-Roll unit is to be added in the future 15

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