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ALMA front-end beam efficiency evaluation. A.M. Baryshev NOVA/SRON/RuG. Outline. band 9 optics measurement system (example) Band 9 efficiency analysis NA FEIC data for band 9 and band 7 Q/A. The beam pattern measurement Set-Up. Typical near field measurements. Amplitude. Phase.

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Presentation Transcript
outline
Outline
  • band 9 optics measurement system (example)
  • Band 9 efficiency analysis
  • NA FEIC data for band 9 and band 7
  • Q/A
far field beam patterns
Far field beam patterns

80% typical aperture efficiency

aperture efficiency
Aperture Efficiency

No central blockage

beam pointing ii
Beam pointing II

X and y axes are beam

offsets in degrees

Red – Pol 0

Green Pol 1

Blue secondary mirror

angular dimensions

cross polar
Cross -polar

-19dB peak, -18dB total power

far field cross pol ratio
Far field cross pol ratio

Red = -10dB

4 dB contour

na feic data b9 near field
NA FEIC data b9, near field

Lambda/4 compensation off

na feic data b9 near field1
NA FEIC data b9, near field

Lambda/4 compensation needs to be looked at

na feic b9 far field
NA FEIC b9 far field

Probe model: OEWG WR22: 33.00-50.00 GHz ?

Aperture efficiency 63.3%, Phase center X, Y, Z: 1.32, -0.83, 289 (mm) (0,-0.94) Deg

Aperture efficiency 65.1%, Phase center X, Y, Z: 1.32, -0.87, 292 (mm) (0, -1.40) Deg

na feic b7 data far field
NA FEIC b7 data, far field

Aperture Efficiency 42.9, Phase center X,Y,Z -- 2.22, 5.92, 103.84 (mm)

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