Self-Calibrating Phased Array Antenna Probes
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Solution Overview
Problem
Existing antenna calibration methods, such as calibration coupler manifolds and external scanners, face limitations in accuracy and practicality due to size constraints, maintenance needs, and the requirement for offline operation, while methods like radiatively coupled probes lack individual calibration, leading to potential inaccuracies.
Innovation Solution
The implementation of self-calibrating low directivity open waveguide antennas mounted around the array face, which overlap to ensure comprehensive coverage, allowing for pair-wise calibration and continuous monitoring of RF performance without additional equipment, enabling real-time adjustments and maintenance-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration coupler manifolds are used for antenna calibration, then calibration can be performed, but the devices are relatively large and cause design problems in the array antenna
Solution Approach 1:
The patent extracts the calibration function from the large manifold structure and implements it using small probe antennas positioned at array elements. This removes the bulky manifold while retaining calibration capability, directly resolving the contradiction between calibration accuracy and device size.
Solution Approach 2:
Instead of using a single manifold to distribute calibration signals, the patent uses multiple probe antennas at different array elements to perform calibration. Each probe acts as an independent calibration source, eliminating the need for large coupling manifolds while maintaining calibration functionality.
2Measurement precision
If calibration coupler manifolds are used for antenna calibration, then calibration can be performed, but the coupling factors at each channel have individual variability which limits accuracy
Solution Approach 1:
The patent implements self-calibration where probe antennas at array elements calibrate themselves by measuring signals from other probes. This eliminates the need for precise manual calibration of each manifold coupling factor, as the system automatically compensates for individual variations through mutual measurement and averaging.
Solution Approach 2:
The patent combines calibration data from multiple probe antennas to perform averaging, which compensates for individual probe variations. By merging measurements from multiple sources, the system achieves higher accuracy than any single probe could provide alone, overcoming the limitation of individual coupling factor variability.
3Measurement precision
If an external scanner is used for calibration, then each radiating element can be measured, but the process requires many moving parts which need maintenance and cannot operate continuously
Solution Approach 1:
The patent replaces the mechanical external scanner with stationary probe antennas integrated into the array structure. This eliminates moving parts entirely, substituting a mechanical measurement system with an electronic one based on signal exchange between fixed probes, thereby improving reliability and eliminating maintenance needs.
Solution Approach 2:
The patent enables continuous calibration operation where probe antennas can perform calibration measurements during normal array operation. Unlike external scanners that require the array to be offline, the integrated probes allow calibration to occur continuously without interrupting the useful action of the antenna system.
4Measurement precision
If an external scanner is used for calibration, then calibration can be performed, but the process is slow and requires normal use of the equipment to stop
Solution Approach 1:
The patent performs calibration measurements in parallel using multiple probe antennas simultaneously, rather than sequentially as with external scanners. This preliminary parallel measurement approach dramatically reduces calibration time while maintaining accuracy through averaging of multiple simultaneous readings.
Solution Approach 2:
The patent merges calibration operations with normal array operation, allowing calibration measurements to occur concurrently with productive use. Multiple probes perform calibration measurements simultaneously during array operation, eliminating the need to stop productivity for calibration while maintaining measurement accuracy.
Data Source
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AI summary
The present invention relates to antenna calibration for active phased array antennas. Specifically, the present invention relates to a built in apparatus for autonomous antenna calibration Accordingly, the present invention provides a method of self-calibration of a plurality of calibration antennas comprising the steps of: (i) selecting two calibration antennas to be calibrated that have a common area in range of both calibration antennas; (ii) selecting at least one radiating element within range of the two calibration antennas; (iii) transmitted a known test signal from the one or more selected radiating elements; (iv) measuring a received signal at each of the two calibration antennas; (v) comparing the received signals at each of the two calibration antennas; and (vi) determining a correction coefficient for each calibration antenna based on the received signals at the said calibration antennas.