Fractal Ground Plane Antenna Multipath Rejection
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Solution Overview
Problem
Global Navigation Satellite System (GNSS) antennas face challenges in achieving an ideal gain pattern with a ground plane that is electrically larger than its physical size, necessary to minimize multipath errors, while maintaining a compact form factor for portable applications.
Innovation Solution
A fractal ground plane design is implemented, which includes a conductive material shaped with fractal patterns that are electrically connected to the antenna, increasing the apparent size of the ground plane by distributing small discontinuities that cancel radiated energy, thereby enhancing the antenna's gain pattern above the horizon and reducing multipath interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the physical size of the ground plane is increased to achieve ideal gain pattern, then the electrical performance is improved, but the device size increases which conflicts with portable product requirements
Solution Approach 1:
The patent applies fractal geometry to transform a two-dimensional ground plane into a structure with effective three-dimensional electrical properties. The fractal pattern creates multiple self-similar iterations that occupy different spatial scales, allowing the ground plane to achieve the electrical equivalence of a much larger area while maintaining a compact physical footprint suitable for portable devices.
Solution Approach 2:
The fractal ground plane employs nested self-similar patterns where smaller fractal iterations are contained within larger ones. This nesting approach allows the ground plane to pack increasing amounts of effective electrical area within a bounded physical space, achieving the desired electrical performance without proportionally increasing the physical dimensions.
2Measurement precision
If a larger ground plane is used to reduce multipath errors, then the antenna performance is improved, but the device becomes less compact
Solution Approach 1:
By utilizing fractal geometry, the ground plane achieves effective electrical area expansion in multiple spatial dimensions simultaneously. This allows the antenna assembly to maintain compact physical dimensions while providing the electrical equivalent of a much larger ground plane, thereby improving location determination accuracy without increasing device size.
Solution Approach 2:
The fractal ground plane changes the electrical parameters of the ground plane by introducing self-similar patterns with specific iteration counts and scaling factors. This transforms the electrical characteristics to achieve better multipath rejection and gain pattern control within the same physical area, improving measurement precision without expanding the antenna assembly.
Data Source
AI summary
A Global Navigation Satellite System (GNSS) electronic circuit is described that uses an antenna and a fractal ground plane conductor or a fractal counterpoise. Some embodiments of the electronic circuit include a first ground plane conductor portion on a first electronic substrate, and a second ground plane conductor portion on a second electronic substrate. The second ground plane conductor portion is shaped to include at least one fractal pattern. The fractal pattern of the second ground plane conductor portion makes the ground plane seem electrically larger than it is. The fractal ground plane conductor portion minimizes the reception of GNSS satellite signals below the antenna, and improves the reception of signals from low elevation GNSS satellites above the horizon.