Group Antenna Feed Network Phase Velocity Mismatch
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Solution Overview
Problem
Existing group antenna feed networks using coaxial cables of equal length face limitations in maintaining phase coherence across radiators, especially in broadband applications, leading to frequency-dependent distortions and beam errors due to the need for phasing loops and fixed line lengths.
Innovation Solution
The use of coaxial cables with different phase velocities allows for the elimination or shortening of phasing loops by varying the signal propagation speed, enabling in-phase feeding and defined phase differences across radiators, even in scenarios where equal-length cables are typically required, thereby accommodating different radiator spacings and frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If equal-length coaxial cables are used from the central feed point to all radiators, then in-phase feeding is achieved at a single frequency, but frequency-dependent phase errors and radiation pattern distortions occur in broadband applications
Solution Approach 1:
The patent applies local quality by using coaxial cables with different phase velocities in different feed lines radiating from the central feed point. Instead of using uniform equal-length cables, each cable is selected with a specific phase velocity characteristic to compensate for the different path lengths to various radiators. This local differentiation in cable properties ensures that signals arrive at all radiators with the correct phase relationship across a broad frequency range, eliminating the single-frequency limitation of traditional equal-length cable systems.
2Measurement precision
If phasing loops are used to maintain equal cable lengths, then in-phase feeding is achieved, but installation space and complexity increase
Solution Approach 1:
The patent extracts and eliminates the need for phasing loops by using coaxial cables with different phase velocities. Instead of adding complex loop structures to equalize path lengths, the solution removes the loops entirely and compensates for path length differences through the selective use of cables with appropriate phase velocity characteristics. This extraction of the phasing loop requirement simplifies the feed network structure and reduces installation space while maintaining precise phase coherence across all radiators.
3Device complexity
If coaxial cables with different phase velocities are used, then phasing loops are eliminated and installation space is reduced, but cable selection and matching become more complex
Solution Approach 1:
The patent applies parameter changes by utilizing coaxial cables with different phase velocity parameters. By changing the phase velocity parameter of the cables rather than changing their physical lengths or adding loops, the system achieves proper phasing without complex structures. This parameter-based approach simplifies the overall feed network while the specific selection of phase velocity values is designed to facilitate practical cable selection and installation, balancing the trade-off between structural simplicity and manufacturing ease.
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
This approach reduces installation space and costs, enhances beam steering capabilities, and minimizes frequency-dependent phase errors, making it suitable for broadband antennas with improved radiation patterns and reduced side-lobe levels.
Implementation Method 1
coaxial cables of different types, in particular coaxial cables which allow a phase of a wave to propagate with a different phase velocity
Data Source
AI summary
A group antenna has at least two transducers disposed offset from one another. A network is provided to supply the transducers. The network comprises coaxial cables running between a distributor and/or summation circuit and the access, connection, and/or supply points of the associated transducer. The network comprises at least two different types of coaxial cable characterized by different phase velocities.