CAY

2-140 GHz CAY Anechoic Chamber

F. Tercero, T. Finn, JM. Serna, JA. López-Fernandez

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

CAY

Overview of CAY AUT

� Frequency Range� 2 GHz-116 GHz

� Waveguide components� Polarisers and OMT

� Horn type antennasSingle feed antenna at room temperature

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Single feed antenna at room temperature

� Feed systems� Horn+Reflector (or dielectric lenses)

� Horn (and lenses) inside of cryostats

� FSS

CAY

Types of measurements

� Far Field patterns (co & xp)� standard antenna verification

� Near Field patterns� Gaussian Beam Mode Propagation in feed

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Gaussian Beam Mode Propagation in feed system

� Axial ratio� verification of polarisers and OMTs measured

in free space

CAY

Are all these kind of antennas similar for the measuring system?

� Directivity

� Hardness of movement (mechanical complexity)� More electrical criteria (Rx/Tx, active/passive, frequency conversion)

Far Field Range Near Field Range

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

WG.COMP HORNS CRYOSTATS SYSTEMS

LOW DIRECTIVITY HIGH DIRECTIVITY

EASINESS OF MOVEMENT HARDNESS OF MOVEMENT

CAY

Dual system: Near Planar + Far Spherical

� Cryostats, Systems & Directive Horns

� The probe scans the aperture field over a plane

� FF=FT(NF)� NF can be measured

directly at several distances from the AUT

Light systems or not very

AUT

PROBE (OEWG)

AUT

PROBE (SGH)

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Light systems or not very directive

� The AUT scans the “plane wave” from the SGH (fixed in the scanner)

� Classical FF Measurement at FF distance

� AUT Rx/Tx

AUT

(OEWG)

PROBE

(OEWG)

AUT

PROBE (SGH)

CAY

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

Dual system: Dimensions� Inspiration � 40m=Cassegrain F/D=7.909

� w0=5.5*λ � Reflector D=22*λ in Cass. Focus

� Planar scanner� f=2 GHz (λ=150mm) D=3300mm� f=5 GHz (λ= 60mm) D=1320mm� Little bit bigger than D of reflector needed

� Z-axis railway� NF measurements up to the confocal distance

(zc=5.52.λ.п)

θ

AU

T A

pert

ure

Sca

n A

rea

1.8 m

� NF measurements up to the confocal distance (zc=5.52.λ.п)

� f=2 GHz (λ=150mm) zc=14000mm� f=5 GHz (λ= 60mm) zc= 5700mm

� Far spherical� FF measurements at 2*D2/λ distance for a 8λ

(≈25 dBi directivity)� f=2 GHz (λ=150mm) R=19200mm� f=5 GHz (λ= 60mm) R= 7600mm

� Range dimensions� 7400 mm LENGTH (AUT to SGH)� 4300 mm WIDTH & HEIGHT (absorbers)

2Φr 2Φv

AU

T A

pert

ure

Sca

n A

rea

4.3 m

5.4 m

7.4 m

CAY

Planar Scanner

� Construction Inverted “T” Frame (steel)� Scan Area 6’x6’ (1.8 m x 1.8 m)� Corrected Planarity 0.001” (0.025 mm) RMS� Resolution (x,y) 0.001” (0.025 mm)� Position Repeatability 0.002” (0.05 mm) RMS� (W, D, H) 3.1m, 1.7m, 3.3m

Polarisation stage (360º probe rotator)

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Polarisation stage (360º probe rotator)

� Measurement of the planarity during the on-site installation and corrected actively

CAY

Spherical Positioner

� Construction Phi over Theta rotation stages with “L” bracket (aluminium)

� Scan Area Full spherical; Phi/Theta - 360°

� Maximum Antenna Load 20 kg at 22 cm CG offset

� Resolution 0.0125° phi and theta

� Position Repeatability 0.03°

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Position Repeatability 0.03°

� Rotational Speed (Theta and Phi) 20°/sec

CAY

RF Instrumentation� f<50 GHz

� Agilent PNA E8364� NSI doubler 20-40 GHz out� NSI quadrupler 33-50 GHz out

� Agilent mixers 2-50GHz 85320A/B-H50

� f>50 GHzAgilent PNA E8364

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Agilent PNA E8364� 50-75 GHz WR15 OML Millimetre Head� 75-110 GHz WR10 OML Millimetre Head� 90-140 GHz WR08 OML Millimetre Head

� RF Instrumentation (PNA+mmHeads) shared for general proposed

� AUT Rx/Tx

CAY

Anechoic Room� Range 7.4 x 4.3 x 4.3 m

� AUT to SGH, distance between absorbers� Exterior 11.5 x 5.0 x 5.0

� Mechanical instrumentation, absorbers and shielding� Shielding

� Sandwich type (galvanized steel plate which sandwich a 19mm wooden core)

� Up to 80 dB shielding up to 40 GHz� Door

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

� Door� 2.0 x 2.5 m semiautomatic shielded door

� 6 Ventilation panels� 2 Flexible penetration panel

� FO� K connectors� He-gas feedtrough

� Absorber� 8´(20cm) and 12´(30cm) combination of pyramidal absorbers� 50dB attenuation from 5 GHz at normal incidence� Left unpainted in critical areas for the mm frequencies

performance� Walkable for access to the instrumentation

CAY

Current Status

Parent building Ready

RF Intrumentation Ready (Agilent)

Ongoing (NSI)

Anechoic Chamber Ongoing (Rainford)

2-140 GHz CAY Anechoic Chamber IVS VLBI2010 Workshop on Future Radio Frequencies and Feeds

Anechoic Chamber Ongoing (Rainford)

Planar Scanner Ongoing (NSI)

Z-axis Railway Ongoing (NSI)

Control & Software Ongoing (NSI)

Far Field Spherical Stopped