Multi-band Satellite Antenna Phase-centre Stability
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Solution Overview
Problem
Existing satellite positioning system antennas face challenges with multipath effects, phase-centre stability, and group delay variations, especially in environments with high RF interference, due to their inability to effectively operate across multiple frequency bands and handle temperature changes.
Innovation Solution
A stacked multi-band antenna design featuring conductive patches and an RF front end with separate triplate sections and orthogonal conductive strips for independent impedance matching, filtering, and amplification, providing self-diplexing properties and high phase-centre stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-band stacked patch antenna is used to operate in multiple frequency bands, then the positioning accuracy and capability are improved, but the phase-centre stability deteriorates due to frequency variations
Solution Approach 1:
The antenna is divided into multiple independent conductive patches, each resonant at a specific frequency band (L1, L2, E5, E6), stacked vertically with parasitic coupling through slots. This segmentation allows each patch to be optimized for its frequency band while maintaining overall phase-centre stability through careful geometric design and positioning.
Solution Approach 2:
Multiple conductive patches are nested in a stacked configuration where smaller patches for higher frequency bands (E5, E6) are positioned within the projection area of larger patches for lower frequency bands (L1, L2). This nested arrangement enables multi-band operation from a compact structure while maintaining phase-centre stability.
2Measurement precision
If the antenna reception pattern is tailored to reduce multipath effects, then the positioning accuracy is improved, but the device complexity increases
Solution Approach 1:
The antenna employs non-isotropic reception patterns with different directional characteristics for different frequency bands. Each conductive patch is designed with specific geometric features (size, shape, positioning) that create locally optimized radiation patterns tailored to mitigate multipath effects in specific directions, improving positioning accuracy without requiring complex external structures.
3Object-affected harmful factors
If separate circuits are used for different frequency bands to achieve independent impedance matching and filtering, then the out-of-band rejection is improved, but the device complexity increases
Solution Approach 1:
The RF front end is segmented into separate independent circuits for different frequency bands (L1, L2, E5, E6), with dedicated impedance matching networks, band-pass filters, and low-noise amplifiers for each band. This segmentation enables independent optimization of each frequency band's performance, achieving high out-of-band rejection while maintaining manageable complexity through modular design.
Solution Approach 2:
Band-pass filters are introduced as intermediary components between the conductive patches and the receiver circuits. These filters selectively pass desired frequency bands while blocking out-of-band signals, acting as mediators that improve out-of-band rejection without requiring complex circuitry in the subsequent signal processing stages.
4Measurement precision
If group delay variations are minimized to improve positioning accuracy, then the measurement precision is improved, but the device complexity increases due to additional filtering and matching circuits
Solution Approach 1:
Band-pass filters and impedance matching circuits are placed in the RF front end before the main signal processing chain, performing preliminary signal conditioning. This preliminary action of filtering and matching early in the signal path minimizes group delay variations that would otherwise affect subsequent processing stages, thereby improving positioning accuracy while keeping the overall system complexity manageable.
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
The antenna achieves improved signal reception and rejection of out-of-band signals, maintaining phase-centre stability and reducing group delay variations across frequency bands, even in harsh interference environments, enhancing positioning accuracy.
Implementation Method 1
Each conductive layer is associated with a specific frequency band and is resonant within the respective frequency band
Implementation Method 2
Each pair of conductive strips is adapted for radiatively coupling to an associate conductive patch of the stack of conductive patches
Data Source
AI summary
A stacked multi-band antenna for a satellite positioning system comprises a stack of conductive patches, which are each dimensioned so as to be respectively operative in a dedicated frequency band. An excitation line section comprising pairs of conductive strips is arranged underneath the stack of conductive patches. Each pair of conductive strips is adapted for radiatively coupling to an associate conductive patch of the stack of conductive patches. An RF front end with at least one electric circuit is arranged in a triplate section underneath the excitation line section for operatively connecting the pairs of conductive strips to a satellite positioning receiver. The at least one electric circuit includes filters and amplifiers for respectively filtering and amplifying signals from the pairs of conductive strips, during antenna operation.