Capacitively Coupled Patch Antenna for GNSS
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Solution Overview
Problem
Existing patch antennas are inadequate for receiving multiple constellation GNSS signals due to poor axial ratio and cross-polarization interference, especially in urban environments, and lack a cost-effective means to achieve dual feed functionality on small high dielectric substrates.
Innovation Solution
A patch antenna configuration using capacitive coupling between feed pins and a resonant metal plate, with a dielectric substrate sandwiched between, providing a 90-degree phase shift and high electrical isolation, allowing for a compact and cost-effective dual feed architecture that maintains a controlled impedance and pure circularly polarized response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single feed ceramic patch antenna is used, then the antenna structure is simple and cost-effective, but the axial ratio is poor and cross-polarization interference is high
Solution Approach 1:
The patent divides the antenna system into two separate feed structures instead of using a single feed. This segmentation allows each feed to be optimized independently, with one feed handling horizontal polarization and the other handling vertical polarization, thereby achieving pure circular polarization response and reducing cross-polarization interference while maintaining structural simplicity
Solution Approach 2:
The patent introduces a ground plane as an intermediary element between the two feeds. The ground plane provides electrical isolation between the two feed structures, preventing mutual coupling and interference, while still allowing both feeds to operate efficiently on the same ceramic substrate
2Reliability
If a dual feed architecture is implemented to improve axial ratio, then the reception of multiple constellation GNSS signals is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the dual feed architecture with a single ceramic substrate, integrating two complete feed structures (each with its own resonant plate and ground connection) onto one substrate. This consolidation maintains the performance benefits of dual feed while reducing overall device complexity compared to using separate antenna elements
Solution Approach 2:
Each feed structure is designed to be multi-functional, capable of handling both horizontal and vertical polarization components. The symmetric design of the two feeds allows either feed to potentially replace the other if needed, providing design flexibility and reducing manufacturing complexity
3Ease of manufacture
If feed pins are physically connected to the resonant metal plate, then the electrical connection is simple, but the electrical isolation between feeds is insufficient
Solution Approach 1:
The ground plane serves as an intermediary that provides electrical isolation between the two feed pins. By connecting each feed pin to ground through separate paths on the ground plane, the design achieves high electrical isolation between feeds while maintaining simple physical connections to the resonant metal plates
Solution Approach 2:
The patent extracts the isolation function from the feed pin connections themselves and places it in the ground plane structure. This separation allows the feed pins to maintain simple physical connections to the resonant plates while the ground plane independently provides the necessary electrical isolation
4Reliability
If external matching components are added to control impedance, then the impedance matching is improved, but the device complexity and size increase
Solution Approach 1:
The patent merges the impedance matching function into the feed pin structure itself. By carefully designing the feed pin geometry, position, and connection to the ground plane, the desired impedance control is achieved without requiring separate external matching components, thereby reducing device complexity and size
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 configuration enhances the axial ratio and reduces cross-polarization interference, enabling improved reception of multiple constellation GNSS signals with reduced noise and increased sensitivity, while minimizing the need for external matching components and maintaining a compact form factor.
Implementation Method 1
the resonant metal plate is capacitively coupled to each of the two feed pins by a capacitive reactance between the resonant metal plate and each of the two feed pins
Implementation Method 2
a dielectric substrate slab sandwiched between the resonant metal plate and the ground plate
Implementation Method 3
This structure constitutes two orthogonal high-Q resonant cavities, one along a first major axis (5) and another along the second major axis (6) of the patch
Data Source
AI summary
Systems and methods relating to patch antennas. A patch antenna has a substrate, a resonant metal plate at one side of the substrate, and a ground plane at the other opposite side of the substrate. Two feed pins are used to couple the antenna to other circuitry. The feed pins pass through the substrate and holes in at the ground plane. The feed pins are physically disconnected from both the resonant metal plate and the ground plane. The feed pins are capacitively coupled to the resonant metal plate to provide an electronic connection between other circuitry and the patch antenna.