Phased Array OTA Calibration for Gain and Delay Compensation
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Solution Overview
Problem
Existing phased array antennas face challenges in achieving increased bandwidth while maintaining a high ratio of main radiated lobe power to side lobe power, and they require reduced weight, size, manufacturing cost, and power requirements.
Innovation Solution
The implementation of over-the-air calibration techniques for phased array antennas, which involve using a calibration signal to compensate for gain and delay offsets in the antennas and associated circuitry, thereby improving the antenna's performance without physical reorientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If phased array antennas use more antenna elements to increase bandwidth, then bandwidth is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The antenna system is divided into multiple antenna elements that can be independently controlled and calibrated. Each element can be individually adjusted to contribute to the overall bandwidth performance while maintaining manageable complexity through modular calibration of each segment
Solution Approach 2:
The patent introduces a calibration dimension by implementing over-the-air calibration capabilities that adjust phase and amplitude parameters across multiple antenna elements. This additional control dimension enables bandwidth expansion without proportionally increasing system complexity, as the calibration process optimizes the interaction between elements
2Power
If phased array antennas increase the number of antenna elements, then main radiated lobe power is improved, but side lobe power increases
Solution Approach 1:
The over-the-air calibration system implements feedback mechanisms that measure the actual radiated pattern and adjust the phase and amplitude parameters of individual antenna elements accordingly. This feedback loop continuously optimizes the main lobe power while suppressing side lobe emissions by compensating for variations in element performance
Solution Approach 2:
The patent dynamically changes the operational parameters (phase and amplitude) of each antenna element based on calibration measurements. By adjusting these parameters, the system maximizes main lobe power while minimizing side lobe power, resolving the contradiction between desired radiation patterns and unwanted emissions
3Manufacturing precision
If traditional calibration methods are used, then manufacturing precision is improved, but device complexity and power requirements increase
Solution Approach 1:
The calibration system performs self-calibration through over-the-air measurements without requiring external calibration equipment or complex manual adjustment procedures. The antenna system uses its own transmitted signals as reference, enabling autonomous calibration that reduces external dependencies and simplifies the overall system architecture
Solution Approach 2:
The patent replaces traditional mechanical or physical calibration methods with electromagnetic field-based over-the-air calibration. This substitution eliminates the need for physical alignment tools, mechanical adjustment mechanisms, and complex calibration fixtures, thereby reducing device complexity while maintaining calibration precision
4Measurement precision
If more calibration circuitry is added to improve calibration accuracy, then measurement precision is improved, but power consumption and weight increase
Solution Approach 1:
The calibration circuitry is designed to perform multiple functions: it serves both as the calibration reference source and as the signal transmission path. The same antenna elements and RF circuits used for normal operation are utilized for calibration measurements, eliminating the need for separate dedicated calibration hardware and reducing overall power consumption
Data Source
AI summary
In an embodiment, an apparatus includes a first radio frequency (RF) section configured to generate a RF calibration signal based on modulating a calibration signal. The calibration signal comprises an orthogonal code based signal. The apparatus includes a second RF section configured to receive the RF calibration signal and configured to generate a received calibration signal based on demodulating the RF calibration signal. The apparatus includes a calibration section. The received calibration signal and a reference signal associated with the RF calibration signal comprise inputs to the calibration section. The calibration section is configured to determine one or more of gain, baseband delay, or RF delay compensation values, based on the inputs, to calibrate the first RF section.