Broadband Helical Antenna Winding Angles for Multipath Error Reduction
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Solution Overview
Problem
Global navigation satellite systems (GNSS) face significant positioning errors due to multipath errors, particularly from signal reflections off the ground, which are exacerbated by variations in antenna patterns across different elevation angles and frequency bands.
Innovation Solution
A circularly-polarized quadruple spiral antenna design with specific winding angles and configurations, including multiple longitudinal sections and parasitic elements, is used to minimize antenna pattern variations in the lower hemisphere and maintain stability in the upper hemisphere across the desired frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional GNSS antenna is used, then signal reception is provided, but multipath errors occur due to reflected signals from the ground surface
Solution Approach 1:
The antenna employs different winding angles in different longitudinal sections to create spatially varying radiation characteristics. The first longitudinal section has a first winding angle that provides suppressed radiation in the lower hemisphere, while the second longitudinal section has a second winding angle that provides suppressed radiation in the upper hemisphere, collectively reducing multipath errors across all directions
Solution Approach 2:
The antenna divides the spiral conducting elements into multiple longitudinal sections, each with distinct winding angles. This segmentation allows independent optimization of radiation patterns for different elevation regions, enabling the antenna to simultaneously achieve low multipath error suppression in both upper and lower hemispheres
2Object-affected harmful factors
If the antenna pattern is designed to suppress lower hemisphere signals, then multipath errors are reduced, but signal reception in the upper hemisphere may be affected
Solution Approach 1:
The antenna divides the spiral conducting elements into multiple longitudinal sections, each with distinct winding angles. This segmentation allows independent optimization of radiation patterns for different elevation regions, enabling the antenna to simultaneously achieve low multipath error suppression in both upper and lower hemispheres
Solution Approach 2:
The antenna employs different winding angles in different longitudinal sections to create spatially varying radiation characteristics. The first longitudinal section has a first winding angle that provides suppressed radiation in the lower hemisphere, while the second longitudinal section has a second winding angle that provides suppressed radiation in the upper hemisphere, collectively reducing multipath errors across all directions
3Adaptability or versatility
If the antenna operates over the whole GNSS frequency range, then comprehensive signal reception is achieved, but maintaining consistent antenna pattern performance across all frequencies is difficult
Solution Approach 1:
The antenna utilizes two distinct winding angles (first winding angle in the first longitudinal section, second winding angle in the second longitudinal section) to maintain consistent radiation pattern characteristics across the entire GNSS frequency range. This parameter variation compensates for frequency-dependent pattern changes, ensuring stable multipath error suppression from 1164-1300 MHz to 1525-1610 MHz
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 antenna design achieves a significant reduction in multipath errors, ensuring reliable signal reception with a sharp drop in antenna pattern near the local horizon and minimal levels in the lower hemisphere, effectively addressing multipath errors across the entire operational frequency range.
Implementation Method 1
a circularly-polarized antenna is utilized in the backfire operation mode
Implementation Method 2
The conducting elements in each section have a constant winding angle (pitch angle, i.e., angle relative to a plane normal to antenna axis) around the cylinder
Data Source
AI summary
A broadband quadruple helical circularly-polarized antenna for receiving circularly polarized GNSS signals includes a dielectric cylinder oriented along a vertical axis; four spiral conductors wrapped around the cylinder; the four spiral conductors divided into an upper longitudinal section and a lower longitudinal section; and inductors connecting corresponding spiral conductors of the top and lower longitudinal sections. The spiral conductors in each section have a constant winding angle around the cylinder. The winding angle of all of the conductors in the same longitudinal section is the same. The winding angle of the upper longitudinal section is smaller than the winding angle of the bottom longitudinal. An excitation circuit is connected to the conductors. A third longitudinal section is below the lower longitudinal section, wherein the third longitudinal section includes conductors wound in an opposite direction relative to the lower longitudinal section.