LEO Satellite Antenna System with Electronically Steerable Array
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Solution Overview
Problem
Current antenna systems for low-Earth-orbit (LEO) satellites face challenges in maintaining constant effective isotropic radiated power (EIRP) distribution over the Earth, particularly at the edge of coverage, due to limited gain and polarization discrimination, which hinders increased data transmission rates and spectral reuse.
Innovation Solution
A microwave antenna system with an electronically steerable planar radiating array and a single or double reflector configuration, optimized for rotational symmetry, allows for electronically scanned beams with one or two degrees of freedom, ensuring isoflux power distribution and adaptable EIRP levels by varying the reflector dimensions and radiating element power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If fixed low-gain antennas are used for LEO satellites, then the field of view coverage is wide (quasi-hemispherical with 65° half-angle), but the gain is limited to approximately 6 dBi at the edge of coverage
Solution Approach 1:
The patent employs electronically steerable beams that can dynamically adjust their direction and focus. The antenna system transitions from fixed low-gain coverage to dynamic high-gain directed beams through electronic control of the radiating elements, allowing the beam to be steered to different positions without mechanical movement.
Solution Approach 2:
The patent changes the operational parameters of the antenna system by using phase shifters and amplitude control on individual radiating elements. This allows transformation from omnidirectional low-gain radiation patterns to directional high-gain beams, effectively changing the antenna's radiation characteristics through electrical parameter adjustment rather than physical reconfiguration.
2Power
If the antenna gain is increased to compensate for differential path losses (12-15 dB increase needed), then the data transmission rate can be increased, but the polarization discrimination capability is limited
Solution Approach 1:
The patent applies different characteristics to different parts of the antenna system. Specific radiating elements or groups of elements are configured with different polarization orientations, allowing the antenna to provide both high gain in the desired direction and simultaneous polarization discrimination capability through spatially varied element properties.
Solution Approach 2:
The antenna system uses composite radiating structures that combine multiple polarization capabilities within a single element design. This allows the antenna to achieve high gain while maintaining the ability to discriminate between different polarization states, effectively integrating multiple functions into a unified radiating structure.
3Measurement precision
If mechanically repointable directive beams are used, then the antenna gain can be increased, but mechanical vibrations are introduced
Solution Approach 1:
The patent replaces the mechanical beam-repointing system with an electronically controlled phased array system. Instead of physically moving antenna components to change beam direction, the system uses electronic phase and amplitude control of individual radiating elements to steer beams, completely eliminating mechanical vibrations while maintaining high gain directional coverage.
4Adaptability or versatility
If electronically steerable planar arrays with many radiating elements are used, then the repointing field can be extended beyond 60°, but the device complexity increases
Solution Approach 1:
The patent divides the antenna system into multiple independently controllable radiating elements or sub-arrays. Each element or subgroup can be controlled individually through phase shifters and amplitude modulators, allowing the system to achieve wide repointing capability by coordinating the radiation patterns of segmented elements rather than requiring a single large complex structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The antenna system achieves enhanced gain and beam control, enabling increased data transmission capacity and spectral reuse while minimizing mechanical vibrations and complexity, compatible with LEO satellite orbits from 0 to 1500 km, and supports efficient power distribution across the Earth's surface.
Implementation Method 1
an antenna optics comprising one or two reflectors with rotational symmetry, the profile of which is optimised in such a way that signals radiated by the radiating array are reflected by the reflector/reflectors
Data Source
Figure 1~2
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Figure 5~6
AI summary
The present invention regards an antenna system (1;5) comprising a reflection system that comprises a reflector (11;52) having a rotational symmetry with respect to an axis of symmetry (12;54). Moreover, the antenna system (1;5) also comprises an electronically steerable planar radiating array (13;53) that is arranged in a focal region (14;55) of the reflection system, has a rotational symmetry with respect to the axis of symmetry (12;54) and is operable to radiate a primary radiofrequency beam oriented in a predefined direction of illumination with respect to the axis of symmetry (12;54) in such a way as to cause a specific region of the reflector (11;52) to be illuminated by said primary radiofrequency beam. Said specific region of the reflector (11;52) is designed, when illuminated by said primary radiofrequency beam, to generate by reflection a secondary radiofrequency beam oriented in at least one predefined direction of transmission with respect to the axis of symmetry (12;54).