The main characteristics of the first chamber are:

•  Dimensions: 7.3 x 4.3 x 4.3 m.
• 18” and 12” pyramidal RAM to measure directly at frequencies above 3 GHz. (from 1.5 GHz with FFT gating techniques).
• AUT positioner system: roll over azimuth, able to support antennas up to 50 Kg. and 2m in diameter. Roll positioner is on a longitudinal table in order to allocate the antenna over the center of the measurement sphere.
• Probe positioner system: polarisation (roll) over an xyz manual positioner in order to align the probe’s z-axis to the centre of the sphere. Alignment system is made with levels, mirrors and an autocollimating theodolite.
• Rotary joints over all positioners.
• Measurement probes: axial corrugated conical horns of high polarisation purity.
• Standard gain horns: Self design to cover the complete frequency band.
• Frequency measurement range: 1.5 – 40GHz.
• Uncertainty for gain measurement: +/-0.164 dB for far field measurement procedure and +/-0.142 dB for near field measurement procedure (2σ).
• Uncertainty for CP pattern measurement (-30 dB level): +/-0.278 dB for far field measurement procedure and +/-0.204 dB for near field measurement procedure (2σ).
• Uncertainty for XP pattern measurement (-30 dB level): +/-0.643 dB for far field measurement procedure and +/-0.615 dB for near field measurement procedure (2σ).

The second anechoic chamber is a large one (dimensions 15.2 x 7.9 x 7.3 m.) and it is shared by a Gregorian Compact Range and a Planar-Cylindrical-Spherical Near Field System, both for measuring large antennas.

The main characteristics of the Gregorian Systems are:

• Dimensions: (main chamber) and 6 x 3 x 2.4 m. (subreflector chamber).
• Absorbing material: pyramidal material and wedges to measure above 6 GHz.
• Gregorian compact range with:

–  Offset parabolic main reflector (projected aperture of diameter 4.5 m.), with cosenoidal sawings of depth 60 cm.
– Elliptical subreflector of diameter 2.2 m. with triangular sawings.
– Accuracy of both surfaces better than ± 70 mm peak.
– Frequency range: 6 GHz (lower limit due to sewing depth) to 100 GHz (upper limit due to the surfaces quality).
– Quiet zone at X band: 2.5 m. diameter (+/-0.25 dB, +/-3º) with crosspolar radiation lower than -35 dB.

• Positioner system:

– For big antennas: roll over elevation over azimuth, equipped with rotary joints up 40 GHz.
– For RCS and small antennas: roll over azimuth positioner over low RCS metallic pylon of ogival section.
– Feeds system: low crosspolar level corrugated horns over polarisation positioner.

• Uncertainty for gain measurement: 0.271 dB (2σ).
• Uncertainty for CP pattern measurement (-30 dB level): +/-0.301 (2σ).
• Uncertainty for XP pattern measurement (-30 dB level): +/-2.21 dB (2σ).

The planar system was built to measure large satellite antennas. The main characteristics of the system are:

• 3 high precision linear elements assure the scanner planarity.
• The lower horizontal guide (6 meters length) that supports the structure is filled with reinforced concrete to increase the rigidity of the scanner.
• The lower horizontal guide is a linear ball spline, that allows a free rotation of the vertical tower (5.5 meters height). The tower leans on the upper horizontal guide.
• The scan area:  4.75 x 4.75 meters
• Frequency band is 1 – 40 GHz
• The maximum horizontal axis velocity is 10 cm/sec and the maximum vertical axis velocity is 33 cm/sec
• Structure weight: Lower horizontal guide: 240 kg,  Upper horizontal guide 160 kg and vertical tower 240 Kg
• Spindles dimensions: horizontal  6 m length, 40 cm diameter, 20 mm step; vertical 5.2 m length, 40 cm diameter 40 mm step
• Positioners: roll over azimuth for AUT and polarization for probe. A linear slide allows the best position of the AUT in the system, to be able to measure different antennas in the planar, cylindrical or spherical systems.The errors of the planar scanner were measured by an independent company (EADS-CASA) with a laser tracker are the most important results are:

– Alignment for basement and vertical tower: 150 mm (peak to peak value)

– Planarity for the planar scanner -Z axis: 0.337 mm (peak to peak value for central area of  4000 x 4500 mm)
– X and Y positioning precision (4750 x 4750 mm): systematic error associated to the spindles: 0.4 mm and random error associated to the controller:  0.1 mm