Semi-Transparent Ground Plane for GNSS Multipath Reduction
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Solution Overview
Problem
Current antenna designs fail to effectively reduce multipath reception in global navigation satellite systems (GNSS) while maintaining high antenna gain and compact size, as they either increase size and weight or lead to active power loss.
Innovation Solution
A semi-transparent ground plane with a controlled distribution of layer impedance, featuring an insulating layer with conductive segments and lumped circuit elements, is used to mount the antenna, which reduces multipath reception by controlling the amplitude and phase of the electromagnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a large, flat ground plane or ground plane with choke ring is used to reduce multipath reception, then multipath rejection capability is improved, but the size and weight of the antenna increase
Solution Approach 1:
The ground plane is segmented into multiple conductive regions with different impedance characteristics. The patent divides the ground plane into a first conductive region, second conductive region, and third conductive region, each with specific impedance values to control surface currents and reduce multipath reception without requiring a large continuous ground plane structure
Solution Approach 2:
Different regions of the ground plane are assigned different local electrical properties through varying impedance values. The patent specifies that the first conductive region has impedance Z1, the second conductive region has impedance Z2, and the third conductive region has impedance Z3, where these impedances are specifically designed to control current distribution and achieve multipath rejection in a compact area
2Object-affected harmful factors
If radar absorbing material is used to suppress surface currents and reduce reflected signals, then multipath rejection is improved, but active power is lost and antenna gain decreases
Solution Approach 1:
The patent changes the electrical parameters of the ground plane by using conductive regions with specific impedance values rather than radar absorbing materials. The impedance parameters Z1, Z2, and Z3 are carefully selected to control surface current suppression while maintaining energy efficiency and antenna gain, avoiding the power loss associated with absorbing materials
3Object-affected harmful factors
If traditional ground plane structures are used to reduce multipath reception, then multipath rejection is improved, but the antenna size remains relatively large for navigation receivers
Solution Approach 1:
The ground plane is divided into multiple conductive regions with different impedance characteristics, allowing multipath rejection functionality to be achieved in a compact area without requiring a large continuous ground plane structure
Solution Approach 2:
Different local impedance regions are created within a compact ground plane structure to control surface currents effectively, achieving multipath rejection in a small footprint suitable for portable navigation receivers
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 achieves a high rejection of multipath signals, maintains high antenna gain, and achieves a compact size, with a down/up ratio of less than -20 dB over the desired angular range, enhancing system performance and reliability.
Implementation Method 1
multipath reception by an antenna is reduced by mounting the antenna on a semi-transparent ground plane with a controlled distribution of layer impedance
Implementation Method 2
A lumped circuit element is electromagnetically coupled to the second conductive segment and to the third conductive segment
Data Source
AI summary
Multipath reception by an antenna is reduced by mounting the antenna on a semi-transparent ground plane that has a controlled distribution of layer impedance over a central region and a peripheral region. The central region includes a continuous conductive segment on which the ground element of the antenna is disposed. The distribution of the layer impedance over the peripheral region is configured by multiple conductive segments electromagnetically coupled by lumped circuit elements. A semi-transparent ground plane can be fabricated by depositing a metal film on a dielectric substrate and etching grooves into the metal film to form a desired pattern of conductive segments. Lumped circuit elements can be fabricated as discrete devices, surface mount devices, and integrated circuit devices. Various semi-transparent ground planes can be configured for linearly-polarized and circularly-polarized radiation.