Phased Array Transceiver Using Optical True-Time Delay
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Solution Overview
Problem
Phased array antennas face the squint phenomenon when using electronic phase shifters for broadband signals, leading to different frequencies aiming at different angles, which is mitigated by true-time delays, but existing photonics-based solutions require generating an RF signal and introducing a delay, which can be complex and prone to electromagnetic interference.
Innovation Solution
A transceiver system that uses a laser light source with multiple wavelengths, a dispersion unit to introduce wavelength-dependent delays, and optical filtering to select and heterodyne spectral components, directly generating RF signals for beamforming and receiving, allowing for flexible wideband multiple-signal beamforming with common components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electronic phase shifters are used at each antenna element to control the viewing angle, then the beam steering capability is achieved, but the squint phenomenon occurs causing different frequencies to aim at different angles
Solution Approach 1:
The patent replaces electronic phase shifters with true-time delay (TTD) units that introduce wavelength-dependent delays to different spectral components. This substitution eliminates the frequency-dependent phase shifting that causes squint, as TTD units process different frequencies differently to maintain proper beam alignment across the entire bandwidth.
Solution Approach 2:
The patent changes the delay parameter introduced to each spectral component based on its wavelength. By introducing wavelength-dependent delays through TTD units, the system compensates for the different propagation times of different frequencies, ensuring that all frequency components arrive at the antenna elements simultaneously and maintain proper beam alignment.
2Manufacturing precision
If true-time delays are introduced to avoid beam squint, then frequency alignment accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent uses a single laser source that generates multiple wavelengths, which are then distributed to multiple antenna elements. This multi-functional approach allows the same optical source to serve multiple purposes: generating the carrier signal, providing reference signals for heterodyning, and enabling beamforming across the array, thereby reducing overall system complexity.
Solution Approach 2:
The patent introduces optical components (laser source, optical modulators, optical TTD units) as intermediaries between the baseband signal and the RF signals transmitted by the antenna elements. This intermediary optical layer simplifies the RF signal generation and beamforming processes by performing operations in the optical domain that are then converted back to RF, reducing the complexity of direct RF signal processing.
3Adaptability or versatility
If optical path switching is used to realize TTD functionality, then beamforming with wide bandwidth is achieved, but the device complexity and EMI susceptibility increase
Solution Approach 1:
The patent replaces optical path switching mechanisms with optical true-time delay units that use dispersive elements (such as diffraction gratings or prism-based systems) to introduce wavelength-dependent delays. This substitution eliminates the need for complex switching mechanisms while achieving the same TTD functionality, thereby reducing device complexity and EMI susceptibility.
Solution Approach 2:
The patent employs dispersive elements that automatically introduce wavelength-dependent delays based on the inherent optical properties of the materials and structures used. The system leverages the natural dispersion characteristics of optical materials to achieve TTD without requiring active control or switching, thereby simplifying the device architecture and reducing EMI susceptibility.
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 stable and flexible beamforming in both transmission and reception, avoiding the squint phenomenon and electromagnetic interference, with high phase stability and broad angular range, suitable for wideband and multi-carrier applications.
Implementation Method 1
a laser light source arranged to provide an optical spectrum comprising a plurality of spaced wavelengths
Implementation Method 2
a dispersion unit arranged to introduce a delay to a plurality of spectral components of the optical spectrum associated with the spaced wavelengths. The delay is dependent on the wavelength of the spectral components
Implementation Method 3
a first heterodyning device configured to generate a signal for transmission by the phased array antenna by heterodyning the selected spectral components associated with different ones of the spaced wavelengths
Implementation Method 4
a modulator configured to modulate spaced wavelengths from the said laser light source with the received signals
Data Source
AI summary
A transceiver for a phased array antenna comprises a laser light source arranged to provide an optical spectrum comprising a plurality of spaced wavelengths. The transceiver further comprises a dispersion unit arranged to introduce a delay to a plurality of spectral components of the optical spectrum associated with the spaced wavelengths. The delay is dependent on the wavelength of the spectral components of the optical spectrum. The transceiver further comprises a first optical filter configured to select a plurality of spectral components received from the dispersion unit. The transceiver further comprises a first heterodyning device configured to generate a signal for transmission by the phased array antenna by heterodyning the selected spectral components associated with different ones of the spaced wavelengths of the laser light source. The transceiver is configured to receive signals from the phased array antenna. The transceiver further comprises a modulator configured to modulate spaced wavelengths from the said laser light source with the received signals. The spaced wavelengths are associated with the spectral components used to generate the signal for transmission. The transceiver further comprises a second heterodyning device configured to heterodyne spectral components associated with different ones of the spaced wavelengths of the laser light source.