GaN Phased Array and Reflectarray Antenna for SAR Weight Reduction
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Solution Overview
Problem
Space-based synthetic aperture radar systems require large antennas to avoid range ambiguity, leading to increased size, weight, and cost, as well as engineering and manufacturing challenges, particularly in achieving high azimuth resolution and efficient signal-to-noise ratios.
Innovation Solution
A modular phased array antenna system with gallium nitride power amplifiers and a reflectarray receive antenna, configured for compactness and efficiency, using a combination of patch antenna elements and reflectarray elements on printed circuit boards, with low noise amplifiers and Wilkinson dividers, to transmit and receive radar signals within a compact housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large antenna is used to avoid range ambiguity in space-based SAR systems, then range ambiguity is avoided, but antenna size, weight, and cost increase
Solution Approach 1:
The patent divides the large antenna into multiple subarrays, each with its own feed network and amplifiers. This segmentation allows the antenna to achieve the required aperture size for range ambiguity avoidance while distributing the weight and complexity across multiple manageable modules that can be deployed in space.
Solution Approach 2:
The patent transitions from a traditional two-dimensional planar array to a three-dimensional volumetric antenna structure. This dimensional change enables the system to achieve the required effective aperture for avoiding range ambiguity while maintaining a more compact overall form factor and reducing the projected area that would otherwise require large deployable structures.
2Reliability
If a large antenna is used to avoid range ambiguity, then range ambiguity is avoided, but manufacturing complexity and cost increase
Solution Approach 1:
The antenna is divided into multiple identical or similar subarray modules that can be manufactured separately using standardized processes and then assembled in space. This modular approach simplifies manufacturing by allowing each subarray to be built with less complex equipment and then combined to form the complete large-aperture antenna system.
Solution Approach 2:
The patent employs deployable and reconfigurable antenna structures that can be compacted for launch and then deployed in space to achieve the full aperture size. This dynamic approach allows the antenna to transition from a compact stowed configuration to a large operational configuration, avoiding the need to manufacture and launch a fully deployed large structure.
3Reliability
If the antenna size is increased, then range ambiguity is avoided, but azimuth resolution decreases in strip map mode
Solution Approach 1:
The patent implements electronically steerable beamforming capabilities that allow the antenna to dynamically adjust its illumination pattern and focus. This enables the system to maintain high azimuth resolution by concentrating energy in the azimuth direction while using the full aperture for range ambiguity avoidance, effectively decoupling the two performance requirements through electronic control rather than fixed geometric constraints.
Solution Approach 2:
By transitioning to a three-dimensional volumetric antenna structure, the system can independently control the effective aperture in different dimensions. This allows the antenna to achieve the required aperture size for range ambiguity avoidance in the range dimension while maintaining optimized illumination and resolution characteristics in the azimuth dimension through selective element activation and beamforming.
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 solution enables a compact, efficient, and cost-effective synthetic aperture radar system that maintains high resolution and signal-to-noise performance, suitable for micro satellite systems, while reducing the need for large, bulky antennas and associated costs.
Implementation Method 1
a transmit antenna array configured to transmit a plurality of radio frequency transmit signals
Implementation Method 2
a reflectarray receive antenna configured to receive radio frequency signals including a plurality of reflectarray antenna elements mounted to a printed circuit board, at least one antenna feed configured to receive radio frequency signals reflected from the plurality of reflectarray antenna elements
Data Source
AI summary
Synthetic aperture radar transmit and receive antenna systems and methods of transmitting and receiving radar signals are disclosed. In one embodiment, a transmit and receive antenna system includes a transmit antenna array configured to transmit a plurality of radio frequency transmit signals, the transmit antenna array including a plurality of patch antenna elements mounted to a printed circuit board, each patch antenna element belonging to a subarray, and one or more power amplifiers, each power amplifier feeding a subarray of the patch antenna elements, and a reflectarray receive antenna configured to receive radio frequency signals including a plurality of reflectarray antenna elements mounted to a printed circuit board, at least one antenna feed configured to receive radio frequency signals reflected from the plurality of reflectarray antenna elements, and at least one low noise amplifier electrically connected to the at least one antenna feed.