Photonic RF Phased Array Transmitter for Cross-Coupling Reduction
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Solution Overview
Problem
Active phased array transmitters face performance limitations due to cross coupling effects, RF bandwidth constraints, true time delay steering challenges, electromagnetic interference, and beam steering control, while existing solutions are often bulky, costly, and inefficient.
Innovation Solution
A radio frequency (RF) phased array transmitter system utilizing an array of conductive patches with photogenerated RF current, where the impedance at gaps is real and frequency-independent, and optically addressed for broadband, thin, conformal, and multi-beam capabilities, using a balanced Mach Zehnder optical modulator for efficient harmonic generation and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If closely spaced antenna elements are used in phased array, then beam steering capability is improved, but cross coupling effects increase and dominate antenna performance
Solution Approach 1:
The patent replaces traditional RF-fed antenna elements with optically excited photodiode elements. Optical signals carry beam steering information to each element without requiring physical RF connections, thereby eliminating cross coupling between closely spaced elements while maintaining beam steering capability through optical phase control.
Solution Approach 2:
The patent introduces optical signals as an intermediary medium to transmit beam steering control information to antenna elements. Instead of direct RF electrical connections that cause cross coupling, optical fibers deliver independent control signals to each photodiode element, acting as an isolating intermediary that prevents electromagnetic interference while enabling precise beam control.
2Use of energy by moving object
If antenna elements are designed for maximum power conversion efficiency, then power conversion is optimized, but impedance matching requirements increase device complexity
Solution Approach 1:
The patent replaces RF electrical power delivery with optical power delivery to antenna elements. Photodiodes convert optical power directly to RF current with inherent impedance matching, eliminating the need for complex RF impedance matching networks while achieving efficient power conversion through the optical-to-electrical conversion process.
Solution Approach 2:
The patent changes the power delivery parameter from RF electrical signals to optical signals. This parameter change fundamentally alters the power conversion mechanism, allowing direct conversion of optical power to RF current in photodiodes with inherent impedance matching, thereby simplifying the overall system while maintaining high efficiency.
3Adaptability or versatility
If active phased array transmitters are designed for wide bandwidth, then RF bandwidth is improved, but true time delay steering and EMI control become more difficult
Solution Approach 1:
The patent replaces RF time delay steering with optical time delay steering. Optical signals can carry wide bandwidth information with precise timing control through optical path length differences, enabling true time delay steering across wide RF bandwidths without the EMI and synchronization problems associated with RF electrical connections.
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 system achieves broadband, multi-octave coverage, efficient harmonic generation, and conformal integration, minimizing weight and size while optimizing power conversion efficiency and beam control.
Implementation Method 1
an optical modulator having a first modulator input, a second modulator input and a modulator output. The first modulator input is for receiving an optical signal, the second modulator input is for receiving an RF signal, and the modulator output is for providing an RF modulated optical signal based on the received optical signal and the received RF signal
Implementation Method 2
Each of the plurality of active sources is formed across its associated one of the plurality of separation gaps. Each of the plurality of active sources is for receiving electrical power, each of the plurality of active sources is for receiving an optical signal, and the plurality of active sources is for generating RF current
Data Source
AI summary
A radio frequency (RF) phased array transmitter system comprises a phased array for generating an RF signal. The phased array comprises conductive patches formed in an array, separation gaps, and active sources. Each of the separation gaps is formed between two adjacent ones of the conductive patches, and each of the active sources is formed across its associated one of the separation gaps. The system further comprises an optical source for generating an optical signal and an RF source for generating an RF signal. In addition, the system comprises an optical modulator coupled to the optical source and the RF source. The optical modulator receives an optical signal and an RF signal, and produces an RF modulated optical signal based on the received optical signal and the received RF signal.