Reconfigurable GNSS Antenna for Urban Multipath Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Consumer GNSS receivers face challenges in mitigating multipath errors, particularly in urban environments where obstacles reflect navigation RF signals, leading to poor precision in Position, Velocity, and Time (PVT) calculations due to the inability to differentiate between Line Of Sight (LOS) and non-LOS signals, which existing complex and costly solutions fail to address effectively.
Innovation Solution
A compact and cost-effective antenna assembly with a reconfigurable radiation pattern, featuring a sectoral design with a narrow aperture in the (x, z) plane and a wide aperture in the (y, z) plane, utilizing multiple aligned antenna elements, a feeding circuit with combiners, phase shifters, and switches to adapt to different multipath conditions, allowing for simpler implementation in consumer devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard omnidirectional antenna is used, then all satellites in view can be received, but multipath reflections from obstacles degrade positioning precision
Solution Approach 1:
The antenna applies different radiation characteristics in different spatial directions: narrow aperture in the (x, z) plane to reject multipath from side obstacles, wide aperture in the (y, z) plane to maintain satellite coverage. This directional differentiation allows the antenna to selectively receive LOS signals while attenuating reflected signals from specific directions.
Solution Approach 2:
The sectoral radiation pattern introduces asymmetry in the antenna's radiation characteristics, with deliberately unequal aperture widths in different planes. This asymmetric design creates a null direction toward typical multipath sources (buildings and obstacles) while maintaining sensitivity toward the sky where satellites are located, thereby reducing multipath error impact.
2Measurement precision
If narrow correlators and complex processing techniques are used, then multipath mitigation is improved, but device complexity and cost increase
Solution Approach 1:
The multipath mitigation function is extracted from the signal processing domain and implemented at the antenna level through physical radiation pattern shaping. By addressing multipath rejection in the spatial domain rather than through complex correlation processing, the receiver's computational complexity is reduced while maintaining precision.
Solution Approach 2:
The patent replaces electronic/software-based multipath mitigation (correlation processing, SQM techniques) with a physical/structural solution (sectoral radiation pattern). This substitution moves the mitigation function from the digital processing domain to the electromagnetic radiation domain, simplifying the overall receiver architecture.
3Adaptability or versatility
If antenna elements are increased to improve satellite coverage, then signal reception is enhanced, but antenna size and complexity increase
Solution Approach 1:
The antenna employs a reconfigurable radiation pattern that can dynamically adjust its aperture characteristics. Through electronic control of the feeding circuit (combiners, phase shifters, switches), the antenna can adapt its beam shape and direction to match varying satellite geometries and multipath conditions, providing versatility without requiring physical expansion.
Solution Approach 2:
The radiation pattern parameters (aperture width, beam direction, gain distribution) are made variable through electronic reconfiguration. By changing these parameters dynamically rather than physically expanding the antenna structure, the system achieves enhanced satellite coverage adaptability while maintaining a compact form factor suitable for consumer devices.
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 solution effectively attenuates multipath reflections, improving PVT precision by enhancing the reception of LOS signals over non-LOS signals, thereby enhancing navigation accuracy in urban canyons and other multipath environments without requiring complex hardware or processing power.
Implementation Method 1
surrounding obstacles will not only increase the error in the determination of the pseudo-range of a satellite because of multipath
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The invention discloses an antenna assembly that may be connected to a standard GNSS receiver. The antenna assembly comprises antenna elements that are configured to shape a radiating pattern which is directional in a direction of movement of the GNSS receiver and which has a FOV above the receiver that may be limited. The signals received in LOS will then have a much better C/N0 than the Non-LOS signals. In some embodiments, the FOV may be twisted leftwards or rightwards depending on a configuration of a vehicle carrying the receiver. In some embodiments, the antenna assembly is capable of operating in a plurality of modes that will differ notably by the FOV of the radiating pattern above the receiver. Switching between modes may be triggered manually or automatically and may be based on a determination of the prevalence and/or type of multipath reflections in the area where the rover moves. This determination may be based on sensor processing or a determination of a coarse position that will give to an index of multipath reflections from a database and/or a map.