In-situ Mutual Coupling Characterization for Scanned Array Antennas
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Solution Overview
Problem
Conventional methods for measuring mutual coupling between antenna elements in large phased array antennas are time-consuming and costly, especially as the number of elements increases, due to the need for multi-channel network analyzers.
Innovation Solution
A system utilizing multiple feed networks and switches allows for the characterization of mutual coupling by switching antenna elements between feed networks and termination impedance, enabling efficient measurement of mutual coupling effects using a 2-port network analyzer, with further processing to account for circuit effects and adjust radiation patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-channel network analyzer is used to measure mutual coupling between antenna elements, then the measurement speed increases, but the cost increases proportionally
Solution Approach 1:
The patent segments the measurement process into multiple sequential steps using a 2-port network analyzer. Instead of measuring all antenna element pairs simultaneously with a multi-channel analyzer, the system divides the measurement into individual 2-port measurements between a reference antenna and other antennas, performing measurements in sequences that reduce the number of channels needed at any one time.
Solution Approach 2:
The patent uses a reference antenna to indirectly measure mutual coupling effects. By measuring the coupling between a reference antenna and other antennas, and then using mathematical relationships to derive the mutual coupling between non-reference antenna pairs, the system avoids needing to directly measure every antenna pair with multiple channels simultaneously.
2Measurement precision
If measurements are taken between each and every pair of antenna elements to determine mutual coupling, then measurement accuracy is maintained, but the time required increases significantly
Solution Approach 1:
The patent performs preliminary measurements of the feed network's electrical characteristics (S-parameters) before conducting mutual coupling measurements. These preliminary measurements are used to calculate compensation values that are applied during the actual mutual coupling measurements, reducing the need for exhaustive pairwise measurements while maintaining accuracy.
Solution Approach 2:
The system uses measured data from reference antenna couplings and feed network characteristics to calculate and apply compensation values for mutual coupling effects. This feedback mechanism allows the system to derive accurate mutual coupling information for all antenna pairs without directly measuring every combination, significantly reducing measurement time while preserving precision.
3Area of stationary object
If the number of antenna elements in the array increases, then the array's coverage and capability improve, but the complexity and time of mutual coupling measurements increase
Solution Approach 1:
The patent employs a universal measurement approach where a single reference antenna and a 2-port network analyzer are used to characterize mutual coupling effects for all antenna elements in the array. This universal method allows the same measurement setup to scale to arrays of any size without requiring additional measurement channels or complex multi-channel equipment, enabling the system to handle large arrays efficiently.
Data Source
AI summary
Various embodiments presented herein relate to determining mutual coupling between a pair of antennas in an array antenna. Various operations presented herein enable comparison between a magnitude and phase of a signal transmitted from a first feed network (via a first antenna) and a magnitude and phase of a portion of the signal received at a second feed network (via a second antenna). Electrical effects engendered by any of the first feed network, a first switch, a first local circuit, the second feed network, a second switch, and a second local circuit can also be determined and their effects mathematically removed. Based upon the foregoing, a mutual coupling between the pair of antenna is determined.