Phased Array OTA Calibration for Gain and RF Delay Offsets
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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 measure and 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
1Manufacturing precision
If phased array antennas use traditional calibration methods, then manufacturing precision can be maintained, but device complexity and calibration time increase
Solution Approach 1:
The patent replaces traditional mechanical cable-based calibration systems with an over-the-air calibration method using wireless signal transmission. This substitution eliminates the need for physical calibration cables and complex mechanical connections, thereby reducing device complexity while maintaining calibration precision through signal-based measurements
Solution Approach 2:
The patent introduces a calibration signal as an intermediary element that mediates between the antenna elements and the measurement system. This calibration signal serves as a common reference that can be wirelessly transmitted and measured, simplifying the calibration system architecture while preserving measurement accuracy
2Measurement precision
If phased array antennas perform initial calibration, then measurement precision improves, but loss of time increases
Solution Approach 1:
The patent performs calibration measurements using over-the-air signals that capture both phase and amplitude information simultaneously in a single measurement step. This preliminary action of capturing complete calibration data upfront eliminates the need for multiple sequential measurements, thereby achieving sub-picosecond phase accuracy while reducing calibration time
Solution Approach 2:
The patent enables continuous calibration operations by using over-the-air signals that can be transmitted and measured without interrupting antenna operations. The calibration process flows continuously through signal transmission and measurement, eliminating idle time between calibration steps while maintaining precision
3Adaptability or versatility
If phased array antennas increase bandwidth, then adaptability improves, but maintaining high main lobe to side lobe power ratio becomes more difficult
Solution Approach 1:
The patent uses over-the-air calibration to dynamically adjust and optimize the radiation pattern parameters across different frequency bands. By measuring and compensating for phase and amplitude variations in real-time across the bandwidth, the system maintains high main lobe to side lobe power ratios while utilizing the full available bandwidth for adaptive operations
Data Source
AI summary
In an embodiment, an apparatus includes a first baseband section to receive a calibration signal; a first radio frequency (RF) section configured to generate a RF calibration signal based on modulating the calibration signal. The calibration signal comprises an orthogonal code based signal. The apparatus includes a second RF section to receive the RF calibration signal and generate a received calibration signal based on demodulating the RF calibration signal; a calibration section; a first antenna electrically coupled to the first RF section and configured to transmit the RF calibration signal; and a second antenna electrically coupled to the second RF section and configured to receive the RF calibration signal. The calibration section is configured to determine one or more of gain, baseband delay, or RF delay to calibrate the first RF section; and the second antenna is switchable between receiving the RF calibration signal and transmitting an encoded data signal.