Satellite Earth stations: What is the typical antenna diameter range (in metres) for standard fixed-satellite service (FSS) Earth stations?
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A27.5 to 30
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B10 to 15
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C30 to 50
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D5 to 10
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E2 to 4
Answer
Correct Answer: 10 to 15
Explanation
Introduction / Context:Earth station antenna size drives link budget performance (gain, G/T) and impacts site cost. Knowing typical diameters helps estimate coverage, EIRP, and regulatory compliance for FSS operations.
Given Data / Assumptions:
- C-band and Ku-band FSS links to geostationary satellites.
- “Standard” fixed Earth stations rather than very small aperture terminals (VSATs).
- Clear-sky link budgets with typical rain margins.
Concept / Approach:
Antenna gain G ≈ (π D/λ)^2 η. At C/Ku bands, Earth stations commonly use dishes roughly 10–15 m for robust international trunking and telephony/TV uplinks; smaller VSATs (1–3.8 m) serve lower-throughput services. Very large 30–50 m dishes are deep-space or radio astronomy class, not standard FSS.
Step-by-Step Solution:
Relate required G/T and EIRP to D via G ∝ D^2/λ^2.Match “standard” station performance to common historical deployments (INTELSAT-class gateways).Select the range that fits typical gateway-class stations (10–15 m).Verification / Alternative check:
Historic INTELSAT/ITU documentation and industry practice list gateway dishes in the ~11–13 m range for C/Ku FSS with high availability.
Why Other Options Are Wrong:
- 5–10 m: more typical of smaller hubs or TVRO uplinks; not the classic standard gateway range.
- 27.5–30 or 30–50 m: exceptional cases (deep space/giant RTs), not standard FSS gateways.
Common Pitfalls:
- Confusing gateway-class dishes with VSAT terminal sizes (sub-3.8 m).
Final Answer:
10 to 15