Why are space communication links moving to Ka-band (20–30 GHz)? Choose the primary technical advantage that motivates this migration (assume link design accounts for propagation impairments).
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AIt offers a much wider available bandwidth for services and carriers
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BIt does not suffer from atmospheric attenuation
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CIt permits the use of smaller antennas due to shorter wavelength alone
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DIt does not suffer from rain attenuation at all
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E—
Answer
Correct Answer: It offers a much wider available bandwidth for services and carriers
Explanation
Introduction / Context:Modern satellites increasingly exploit Ka-band to meet exploding capacity demands from broadband and video. This question probes the main technical driver behind choosing Ka-band despite its well-known propagation challenges.
Given Data / Assumptions:
- Ka-band spans roughly 20–30 GHz for satellite services.
- Higher frequency bands provide more spectrum allocation opportunities.
- Propagation issues (rain fade, atmospheric absorption) can be mitigated with link design (power, coding, adaptive modulation).
Concept / Approach:
The primary motivation is access to larger contiguous bandwidth, enabling higher aggregate throughput. While smaller antennas are possible due to shorter wavelengths, that is a secondary practical benefit; crucially, statements claiming “no atmospheric or rain attenuation” are incorrect—Ka-band is more susceptible and needs mitigation.
Step-by-Step Solution:
Identify the real advantage: spectrum availability → capacity growth.Reject claims removing physical propagation limits (rain/atmosphere still affect Ka).Select the bandwidth argument as the most accurate and general reason.Verification / Alternative check:
Operator whitepapers and textbooks cite “more bandwidth at Ka-band” as the core reason for adoption, with engineering countermeasures to handle higher fades.
Why Other Options Are Wrong:
- “No atmospheric or rain attenuation” is factually wrong; Ka-band is more fade-prone.
- “Smaller antennas” can be true, but is not the primary capacity driver compared to bandwidth availability.
Common Pitfalls:
Assuming Ka-band is superior in every respect. It provides capacity, but needs robust fade mitigation techniques.
Final Answer:
It offers a much wider available bandwidth for services and carriers