Optically-Fed Phased Array for Multi-User MIMO Beam Steering
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Solution Overview
Problem
Current phased arrays for radio-frequency beam transmission face challenges in efficiently directing multiple communication channels to different locations with high frequency agility and precision, particularly in conformal and wideband applications.
Innovation Solution
The use of an optically-fed transmitting phased-array architecture that converts RF signals into optical sidebands, allowing for simultaneous generation and focusing of RF beams on selectable locations through electro-optic modulators and photodiodes, enabling multiple channels to be transmitted simultaneously with high pointing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional phased arrays are used for RF beam transmission, then beam direction control is achieved, but frequency agility and precision are limited
Solution Approach 1:
The patent replaces conventional electronic phase shifters and RF signal processing mechanisms with an optically-fed phased array system. Optical modulators convert RF signals to optical domain for processing, enabling precise beam control through optical path length adjustments rather than traditional electrical phase manipulation. This substitution achieves both high frequency agility through optical domain flexibility and precise beam pointing through accurate optical path control.
Solution Approach 2:
The system changes the operating domain from electrical to optical by using optical modulators and photodiodes. The RF signals are converted to optical signals, processed in the optical domain with different parameters (optical frequency, wavelength), and then converted back. This parameter transformation enables superior frequency agility and beam precision that are not achievable with conventional electrical phased arrays operating at the same RF frequencies.
2Productivity
If multiple communication channels are directed to different locations simultaneously, then communication capacity increases, but system complexity increases
Solution Approach 1:
The optically-fed phased array architecture provides a universal platform that can simultaneously handle multiple communication channels directed to different locations. The system uses a common optical distribution network that can be dynamically configured to serve multiple users and channels. This multi-functional approach allows the same hardware infrastructure to support diverse communication scenarios (different frequencies, different beam directions, different modulation schemes) without requiring separate dedicated systems for each channel, thereby increasing communication capacity while managing system complexity through resource sharing.
3Adaptability or versatility
If conformal and wideband phased arrays are designed, then application versatility improves, but manufacturing and design difficulty increases
Solution Approach 1:
The patent employs a modular architecture where the phased array is divided into independent antenna elements, each fed by separate optical channels. This segmentation allows the array to be manufactured in modular units that can be assembled into conformal configurations on various surfaces. Each module can be independently manufactured and tested, then combined to form the complete wideband phased array system. This modular approach significantly eases manufacturing compared to designing and building monolithic conformal arrays, while maintaining the ability to achieve versatile applications through different geometric arrangements of the modular elements.
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
This solution allows for precise and efficient transmission of multiple RF beams to different locations, achieving high frequency agility and wideband operation, thereby overcoming the limitations of existing technologies in conformal and wideband phased arrays.
Implementation Method 1
transmitting signals are converted between the electrical domain and the optical domain by using electro-optic (EO) modulators
Implementation Method 2
Desired RF signals may be recovered by photo-mixing at the photodiodes
Data Source
AI summary
An transmitter to be used in wireless multi-user MIMO has been described above. The system combines the virtues of digital, analog and optical processing to arrive at a solution for scalable, non-blocking, simultaneous transmission to multiple UE-s. The system architecture is independent of the RF carrier frequency, and different frequency bands can be accessed easily and rapidly by tuning the optical source (TOPS). The data channels are established in the digital domain and the RF beam-forming accuracy is only limited by the available resolution of DAC, which can be as high as 16 bits for 2.8 GSPS in off-the-shelf components.