Alma front end beam efficiency evaluation
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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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ALMA front-end beam efficiency evaluation

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Alma front end beam efficiency evaluation

ALMA front-end beam efficiency evaluation

A.M. Baryshev

NOVA/SRON/RuG


Outline

Outline

  • band 9 optics measurement system (example)

  • Band 9 efficiency analysis

  • NA FEIC data for band 9 and band 7

  • Q/A


Alma front end beam efficiency evaluation

The beam pattern measurement Set-Up


Typical near field measurements

Typical near field measurements

Amplitude

Phase


Far field beam patterns

Far field beam patterns

80% typical aperture efficiency


Aperture efficiency

Aperture Efficiency

No central blockage


Beam pointing i

Beam pointing I


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


Focus offset x y

Focus offset (x,y)


Beam squint

Beam squint


Defocus

Defocus


Co polar

Co-polar


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 near field

NA FEIC b7 data, near field


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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