2. Antenna Structure

2.4 Specification Summary

2.4.1 Conditions

 

Parameters

Specifications

Precision

Wind, continuous

Wind, gusts

< 25 km/h

20÷ 30 km/h
Sun Absent
Precipitation Absent
Temperature -25 ÷ 30 °C
Humidity < 90 %

Normal

Wind, continuous

Wind, gusts

< 65 km/h

50 ÷ 80 km/h
Precipitation Absent
Temperature -30 ÷ 50 °C
Humidity < 100%
Survival Wind 200 km/h
Precipitation < 5 cm/h snow
Seismic 0.3 g horizontal

Tab. 2.5 : Observation conditions

In survival conditions, and when not in use, the antenna must be settled at 90° elevation and 295.151° azimuth (stow position).

2.4.2 Surface Accuracy

Structural Elements

(RSS mm)

90° El

(RSS mm)

60° El
Primary reflector panels 0.1 0.1
Secondary reflector panels 0.38 0.38
Gravitational deformation 0 0
Total surface accuracy 0.2 0.2

Tab. 2.6 : Surface accuracy at 90° and 60° elevation

To estimate the phase error ε from the surface accuracy, the following can be used :

δ = surface accuracy

λ = observation wavelength

Usually a maximum tolerable phase error is assumed as ε≈36°≈0.63 rad , so that the minimum observable wavelength is

 

This means for the Noto antenna :

2.4.3 Pointing accuracy

Condition Pointing accuracy

(rms arcmin)
Normal/Precision 0.13

Tab. 2.7 : Pointing accuracy

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