Phased Array Antenna Calibration Using Interfering Structure Correction
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Solution Overview
Problem
Existing phased array antenna calibration methods are costly and inaccurate, especially when antennas are electromagnetically coupled to interfering structures, and they struggle to account for electromagnetic coupling in confined spaces or when recalibrating in the field.
Innovation Solution
A system that computes a modified calibration ratio using an RF source close to the antenna, simulating far-zone and near-zone conditions to account for interfering structures, and adjusts the calibration ratio by combining internal and external signal measurements with a correction factor, allowing for calibration in environments where traditional methods are impractical.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods using distant external calibration sources are used, then calibration accuracy is improved, but the method becomes impractical in confined spaces and field recalibration scenarios
Solution Approach 1:
The patent introduces an intermediary correction factor that accounts for electromagnetic coupling effects between the antenna and interfering structures. This correction factor acts as a mediator that allows near-field calibration signals to achieve far-field equivalent accuracy by mathematically compensating for the presence of interfering structures, thus resolving the contradiction between using close calibration sources and maintaining calibration accuracy.
Solution Approach 2:
The patent changes the calibration approach from requiring distant sources to using near-field sources by introducing a correction factor that transforms the calibration ratio. This parameter change allows the system to use conveniently placed calibration sources while maintaining accuracy through mathematical correction of the measured calibration ratio to account for electromagnetic coupling effects.
2Adaptability or versatility
If calibration is performed in the presence of interfering structures, then field recalibration becomes possible, but calibration accuracy deteriorates due to electromagnetic coupling effects
Solution Approach 1:
The patent converts the harmful electromagnetic coupling effect into a beneficial correction opportunity. By explicitly modeling and measuring the coupling effect between the calibration source and interfering structures, the system uses this previously harmful interaction to generate a correction factor that improves calibration accuracy in field conditions, turning the interference into a useful calibration enhancement.
Solution Approach 2:
The patent implements a feedback mechanism where the measured calibration ratio is corrected using a pre-computed correction factor that accounts for electromagnetic coupling. This feedback loop allows the system to compensate for interference effects by comparing measured values against modeled expectations and applying appropriate corrections, thereby maintaining accuracy despite the presence of interfering structures.
3Ease of operation
If external calibration sources are placed close to the antenna, then calibration can be performed in confined spaces, but electromagnetic coupling with interfering structures increases measurement errors
Solution Approach 1:
The patent applies preliminary action by pre-computing the correction factor for electromagnetic coupling effects before performing the actual calibration. The correction factor is calculated in advance based on the known geometry and electromagnetic properties of the interfering structures, allowing the field calibration to proceed accurately without needing to measure or know the exact coupling effects during calibration execution.
Solution Approach 2:
The patent replaces the mechanical approach of physically distancing calibration sources from interfering structures with an electromagnetic/mathematical solution. Instead of mechanically positioning sources far away to avoid coupling, the system uses electromagnetic modeling and mathematical correction factors to compensate for coupling effects, substituting physical separation with computational correction.
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
Enables accurate and cost-effective calibration of phased array antennas in the presence of interfering structures, even in confined spaces, by simulating electromagnetic coupling and adjusting for interference, thereby improving directional sensitivity and reducing side lobe levels.
Implementation Method 1
RF simulation unit operative to generate simulated first electro-magnetic coupling-zero far-zone external fields projected toward the antenna from an RF source located at a far-zone distance from the antenna, assuming that first electro-magnetic coupling between the mutually electro-magnetically coupled antenna elements to be zero
Implementation Method 2
Each element, or group of elements, is driven by a transmit/receive (T/R) module which controls the phase and the amplitude of the corresponding antenna element
Implementation Method 3
The signals transmitted through the antenna elements interfere with each other. By selecting suitable values of the relative amplification and the relative phase-shifting between the modules and by utilizing the interference of the transmitted signals, the directional sensitivity of the antenna can be controlled
Data Source
AI summary
A method for calibrating an antenna comprising a phased array of antenna elements connected to a plurality of transceivers, the method comprising providing an RF source located close to the antenna and synchronized with the transceivers, determining, per antenna element, a calibration ratio adapted to accommodate for presence of at least one interfering structure electromagnetically interfering with a signal transmitted from the RF source and received by the antenna, wherein the determining includes generating simulated far field and near field signals so as to simulate a signal transmitted by an RF source located at infinity and located near the RF source respectively, internally injecting an internal signal into the antenna via an internal injection network, using the RF source to externally inject an external signal into the antenna; and, for each individual antenna element, computing said calibration ratio by combining information characterizing the internal and external signals as received by the individual antenna element with a correction factor characterizing the simulated far field and near field signals; and calibrating the antenna using the per-antenna element calibration ratios adapted to accommodate for presence of at least one interfering structure.