Microwave Photonics Beam Forming Eliminates Squint
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Solution Overview
Problem
Conventional RF designs face limitations in bandwidth and dynamic range, leading to beam squint and reduced data rates, especially with the increasing use of wide bandwidth channels and high-order modulation schemes in satellite, airborne, and ground communications.
Innovation Solution
The use of microwave photonics-enabled systems with optical frequency combs and Fiber-Bragg gratings allows for true-time delay beam forming, independent of RF signal frequency and bandwidth, enabling wide-band squint-free operation and efficient channelization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional RF phase shifters are used for beam forming, then electronic control of beam direction is achieved, but beam squint occurs and bandwidth is limited
Solution Approach 1:
The patent replaces conventional RF electronic phase shifters with a photonic true-time delay beam forming system. Optical frequency combs and Fiber-Bragg gratings are used to create time delays in the optical domain, which are then converted to RF signals. This substitution eliminates beam squint and enables wide bandwidth operation while maintaining electronic beam steering control.
Solution Approach 2:
The patent introduces an optical domain as an intermediary between the RF input and output. RF signals are modulated onto optical frequency combs, processed through Fiber-Bragg gratings for time delay, and then converted back to RF. This intermediary approach allows true-time delay beam forming independent of RF frequency, resolving the beam squint issue.
2Measurement precision
If high sampling rate ADCs are used for digital beam forming, then beam forming accuracy is improved, but ADC resolution decreases
Solution Approach 1:
The patent replaces high-speed ADCs with photonic true-time delay beam forming. By performing beam forming in the optical domain using frequency combs and Fiber-Bragb gratings, the system achieves high precision beam steering without requiring high sampling rate ADCs, thereby preserving ADC resolution for the actual data conversion.
3Productivity
If bandwidth efficient modulation schemes are used, then data rate increases, but front end RF and digital sampling components face challenges
Solution Approach 1:
The patent replaces complex RF and digital sampling components with a photonic beam forming system. By using optical frequency combs and Fiber-Bragg gratings, the system achieves wide bandwidth processing capability that supports high-order modulation schemes without requiring complex high-speed ADCs and sophisticated RF front-end design.
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 approach eliminates beam squint, reduces the need for high-resolution ADCs, and allows for scalable beam forming and channelization, supporting high-bandwidth and high-data-rate communications without the limitations of traditional RF designs.
Implementation Method 1
an optical frequency comb that is configured to generate a multitude of equidistantly spaced optical wavelengths
Implementation Method 2
each FBG having different wavelength dispersion properties, such that different time delays are introduced between different wavelengths in each fiber
Data Source
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AI summary
A receiver and a transmitter are disclosed that are applicable to space, air or ground RF communication systems and are applicable to systems where one or more signals of multiple types and characteristics are present in any given beam such as a communication spot beam on a high-throughput satellite. The transmitter can include an optical frequency comb configured to generate a multitude of equidistantly spaced optical wavelengths; an electro-optic modulator that receives the multitude of equidistantly spaced optical wavelengths and a data signal and produce a modulated optical beam; an optical circulator that receives the modulated optical beam; an optical switch that switches the modulated optical beam to an output port of the optical switch terminated in one or more Fiber-Bragg gratings; a wavelength division multiplexer that receives individual wavelengths of the modulated optical beam that are time-delayed from the optical circulator; and a plurality of antenna elements.