Low Profile Dual Frequency GNSS Antenna Structure
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Solution Overview
Problem
Current GNSS dual frequency antennas face challenges in achieving wideband performance and rejecting multipath interference due to high dielectric constants in ceramic materials, which limit bandwidth and increase costs, and require precise tuning and phase alignment that is difficult to achieve with single feed points.
Innovation Solution
A low-profile GNSS dual frequency antenna structure using a lower dielectric constant for the lower frequency patch and a higher dielectric constant for the higher frequency patch, with dual or quad feed points to maintain polarization and bandwidth, and a hybrid splitter to ensure 90-degree phase rotation, reducing the impact of tolerances and enhancing multipath rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a high dielectric constant ceramic material is used for the antenna patch, then the antenna size is reduced, but the bandwidth is narrowed and manufacturing precision becomes more difficult to achieve
Solution Approach 1:
The patent changes the dielectric constant parameter of the substrate material from high (ceramic, ~10) to low (printed circuit board material, ~3), which fundamentally alters the antenna's electrical characteristics. This parameter change allows the antenna to achieve the required performance with standard manufacturing tolerances while maintaining a compact form factor through optimized patch dimensions and feed point configuration
Solution Approach 2:
The patent replaces expensive ceramic substrates with inexpensive printed circuit board materials, making the antenna more cost-effective and easier to manufacture. This substitution enables mass production with standard PCB fabrication processes while achieving the required electrical performance through careful design of the patch and feed network
2Device complexity
If a single feed point is used for dual frequency operation, then the device complexity is reduced, but the bandwidth and polarization stability are compromised
Solution Approach 1:
The patent divides the feed system into multiple independent feed points (dual or quad configuration) rather than using a single feed point. Each feed point is strategically positioned and impedance-matched to independently excite specific resonant modes of the patch antenna, enabling dual-frequency operation with stable circular polarization and broad bandwidth while maintaining manageable device complexity
3Adaptability or versatility
If the antenna is designed for wide beamwidth to accommodate vehicle motion, then the adaptability is improved, but the multipath rejection capability is reduced
Solution Approach 1:
The patent employs a mechanically adjustable support structure that allows the antenna to be dynamically repositioned between different heights and orientations. This dynamic configuration enables the antenna to adapt its radiation pattern characteristics - achieving wide beamwidth when mounted higher for vehicle applications with significant pitch and roll, and achieving steeper roll-off at the horizon when mounted lower for multipath rejection in high-accuracy applications
Solution Approach 2:
The patent designs a universal antenna system that can serve multiple applications through a single adjustable platform. The same antenna structure can be configured for wide-beamwidth operation in mobile platforms (aircraft, small watercraft) or for multipath-rejection operation in high-accuracy applications, making the system versatile across different GNSS application scenarios
Data Source
AI summary
GNSS signals are centered around two bands, L1 and L2, and antennas must cover both these bands for good RTK performance. GPS is at a lower frequency in both bands than the Russian GLONASS system. What is described herein is a method of constructing a low profile dual frequency wideband antenna with excellent polarization and signal reception for both GPS and GLONASS. This technique minimizes the impact of tolerances of the dielectrics, thicknesses and tuning by optimal construction.