Spectral Replication for Ultra Small Aperture Satellite Antennas
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Solution Overview
Problem
Ultra small aperture antennas in satellite communication systems face challenges due to reduced G/T ratio and increased Adjacent Satellite Interference (ASI), making them impractical for use, especially in low-cost applications like Direct To Home (DTH) services, as they struggle to overcome thermal noise and interference with limited satellite power.
Innovation Solution
A satellite communication system that uses spectral replication to boost power density by transmitting multiple spectral replicas, which are coherently combined in frequency and phase at the receiving end, enabling the use of ultra small aperture antennas by increasing power and gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ultra small aperture antennas are used, then cost is reduced and portability is improved, but G/T ratio degrades and ASI interference increases
Solution Approach 1:
The signal is divided into multiple spectral replicas transmitted at different frequencies. The receiving antenna receives all replicas and the combiner merges them coherently, achieving signal diversity without requiring a larger physical aperture.
Solution Approach 2:
The system transitions from spatial diversity (multiple physical antennas) to frequency diversity (multiple spectral replicas). By replicating the signal across multiple frequency components, the system achieves the diversity gain needed to overcome the limited aperture size of small antennas.
2Ease of manufacture
If ultra small aperture antennas are used, then cost is reduced, but ASI interference increases
Solution Approach 1:
The signal is divided into multiple spectral replicas transmitted at different frequencies. The receiving antenna receives all replicas and the combiner merges them coherently, achieving signal diversity without requiring a larger physical aperture.
Solution Approach 2:
Multiple copies of the same signal are transmitted at different frequency locations. The receiver identifies and combines these copies, creating a robust signal that overcomes interference from adjacent satellites operating on the same frequency band.
3Reliability
If satellite power (EIRP) is increased, then link performance improves, but cost increases
Solution Approach 1:
The signal is divided into multiple spectral replicas transmitted at different frequencies. The receiving antenna receives all replicas and the combiner merges them coherently, achieving signal diversity without requiring a larger physical aperture.
Solution Approach 2:
The system transitions from spatial diversity (multiple physical antennas) to frequency diversity (multiple spectral replicas). By replicating the signal across multiple frequency components, the system achieves the diversity gain needed to overcome the limited aperture size of small antennas.
Data Source
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AI summary
A system for enabling use of ultra-small aperture terminals in satellite communications is provided. The system comprises a transmitter configured to receive an input signal having information, a bandwidth, and an amplitude, replicate the input signal into two or more replications of the input signal, convert each of the two or more replications to have a frequency tuned to two or more corresponding satellite transponders while maintaining the bandwidth and all the information of the input signal, and combine the two or more replications into a single uplink signal. A transmit antenna is configured to transmit the uplink signal to the two or more satellite transponders.