Combined Cellular/GNSS Antenna Layout for Low Mutual Coupling
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Solution Overview
Problem
Modern high-precision positioning receivers face interference and positioning errors due to mutual coupling between cellular and GNSS antennas, which are exacerbated by the close proximity and asymmetrical designs of these antennas, leading to distorted radiation patterns and increased backlobe levels in the GNSS antenna.
Innovation Solution
A compact combined cellular/GNSS antenna design featuring a cellular antenna with a circular array of radiators and a symmetrical feeding network, orthogonal to the GNSS antenna, which reduces mutual coupling by exciting orthogonal spherical harmonics and minimizing the backlobe of the GNSS antenna.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cellular and GNSS antennas are located close to each other to reduce housing dimensions, then the overall device size is reduced, but mutual coupling between the antennas increases causing interference during GNSS signal reception
Solution Approach 1:
The patent positions the cellular antenna laterally adjacent to the GNSS antenna rather than vertically stacked, utilizing lateral spacing to reduce mutual coupling while maintaining compact overall dimensions. This dimensional arrangement allows both antennas to coexist in a small footprint without excessive interference.
Solution Approach 2:
The patent employs a ground plane with non-uniform characteristics, including specific grounding patterns and impedance variations in different regions. This local optimization of ground plane properties reduces mutual coupling between the antennas while maintaining proper signal reference returns.
2Object-affected harmful factors
If the cellular antenna is oriented sideways relative to the GNSS antenna to improve isolation, then isolation between antennas improves, but the cellular antenna negatively affects the radiation pattern of the GNSS antenna causing phase center offset and back lobe increase
Solution Approach 1:
The patent employs an asymmetrical ground plane configuration specifically designed to counterbalance the asymmetrical positioning of the cellular antenna. This tailored asymmetry in the grounding structure compensates for the phase center offset and restores symmetry to the GNSS antenna's radiation pattern.
Solution Approach 2:
The patent optimizes specific parameters including the ground plane impedance, cellular antenna height, and lateral spacing distance. By carefully adjusting these parameters, the design achieves both good isolation and maintains proper radiation pattern characteristics for the GNSS antenna.
3Volume of moving object
If the lateral dimension of the receiver housing is reduced, then the device becomes more compact, but the ground plane of the GNSS antenna decreases causing increased back lobe level and greater positioning error
Solution Approach 1:
The patent transitions from relying on large lateral ground plane dimensions to achieving proper grounding through vertical and strategic lateral placement. The ground plane is optimized in the vertical dimension and strategically positioned rather than simply expanded laterally, allowing compact housing while maintaining adequate ground plane effectiveness.
Solution Approach 2:
The patent implements a non-uniform ground plane with different impedance regions and selective grounding patterns. This local optimization ensures that the ground plane provides adequate reference return paths and maintains proper radiation characteristics even when the overall ground plane area is reduced for compact housing.
Data Source
AI summary
A combined cellular/GNSS (global navigation satellite systems) antenna is provided. The combined cellular/GNSS antenna comprises an external area and an internal area delineated by a circumference of a circle. The combined cellular GNSS antenna further comprises a cellular antenna and a GNSS antenna. The cellular antenna comprises a set of cellular radiators disposed in the external area and connected to a cellular feeding network for excitation of the set of cellular radiators. The GNSS antenna comprises radiation elements disposed in the internal area and has a center located substantially at a center of the circle.