Sideband Self-Calibration for Phased Array Antenna Mutual Coupling
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Solution Overview
Problem
Phased array antenna systems face performance degradation due to mutual coupling between antenna elements, which existing self-calibration techniques fail to accurately account for, especially when blow-by effects from other components in the system obscure the mutual coupling signals.
Innovation Solution
The system employs sideband-based self-calibration by transmitting a calibration signal with a modulation frequency added to the center frequency, allowing the analysis of sidebands offset from the center frequency to determine path loss and phase shifts between antenna elements, thereby isolating the impact of mutual coupling while mitigating blow-by effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing self-calibration techniques are used to measure signal paths between antenna elements, then calibration can be performed, but blow-by effects from other components obscure the mutual coupling signals and reduce measurement accuracy
Solution Approach 1:
A dedicated calibration antenna element is introduced as an intermediary component specifically for calibration purposes. This calibration element is positioned to minimize blow-by effects while maximizing mutual coupling measurements. By using this specialized intermediary element, the system can accurately measure mutual coupling between antenna elements without the obscuring effects that plague conventional calibration approaches.
Solution Approach 2:
The calibration process is segmented into distinct phases: transmitting calibration signals from the dedicated calibration element, receiving signals at other antenna elements, measuring mutual coupling effects, and applying calibration corrections. This segmentation allows the system to isolate and measure mutual coupling effects separately from blow-by effects, thereby improving measurement accuracy.
2Volume of moving object
If antenna elements are closely packed to achieve compact phased array design, then array compactness is improved, but mutual coupling between elements increases and degrades performance
Solution Approach 1:
The system performs self-calibration by measuring mutual coupling effects between antenna elements using dedicated calibration signals and a calibration element. The measured mutual coupling characteristics are then used to compute calibration weights that compensate for the harmful coupling effects. This feedback loop allows the system to maintain compact antenna spacing while actively correcting for the resulting mutual coupling interference, thereby preserving array performance.
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 enhances the accuracy of self-calibration by isolating over-the-air mutual coupling from blow-by effects, leading to improved beam quality and performance in phased array antenna systems.
Implementation Method 1
The calibration signal may include a first signal at a first frequency and that is modulated by a second signal at a second frequency
Implementation Method 2
The system may receive the calibration signal (as transmitted via the first antenna element) via a second antenna element of the antenna array
Data Source
AI summary
Methods, systems, and devices are described for calibration of an array antenna system. A device may transmit a calibration signal from a first antenna element of an antenna array. The calibration signal may be generated by modulating a first signal having a first frequency with a modulation signal having a second frequency. The device may receive the calibration signal using a second antenna element of the antenna array. The device may analyze a sideband of the received calibration signal, where the sideband may be offset in frequency from the first frequency by the second frequency. The device may calibrate the array antenna system based on or more measured properties of the sideband.