Low-Profile GNSS Antenna Structure for Broadband Circular Polarization
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Solution Overview
Problem
Current compact broadband global navigation satellite system (GNSS) antennas lack uniform radiation coverage of the upper hemisphere and circular polarization purity, which affects cross-polarization rejection and multipath rejection, and are not optimized for low-profile, low-weight, and small-footprint applications that require operation across multiple GNSS systems.
Innovation Solution
The design employs a compact antenna structure with coupled dipole resonator elements, including a ground plane, dipole elements, parasitic elements, and ground elements, optimized for circularly polarized signals, to provide improved bandwidth and gain at low elevations, enabling operation across multiple GNSS systems with reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If compact antenna structure is used, then size and weight are reduced, but radiation pattern uniformity deteriorates
Solution Approach 1:
The antenna is divided into multiple dipole elements (first dipole element, second dipole element, third dipole element, fourth dipole element) arranged in a specific configuration. Each dipole element contributes to the overall radiation pattern, and their combined effect achieves uniform coverage of the upper hemisphere while maintaining a compact structure. The segmentation of the antenna into discrete functional elements allows optimization of both size and radiation characteristics.
Solution Approach 2:
The antenna employs asymmetric positioning of dipole elements relative to the ground plane, with specific elements placed at different heights and orientations. This asymmetric configuration, combined with parasitic elements strategically positioned near certain dipoles, creates a radiation pattern that uniformly covers the upper hemisphere while keeping the overall antenna structure compact and low-profile.
2Area of stationary object
If compact antenna structure is used, then footprint area is reduced, but circular polarization purity deteriorates
Solution Approach 1:
The antenna uses four separate dipole elements instead of a single element, allowing each to be optimized for circular polarization performance. The segmented structure enables precise control of current distribution and phase relationships, achieving high circular polarization purity (low axial ratio) within a compact footprint. Each dipole can be independently tuned to contribute to the circularly polarized radiation.
Solution Approach 2:
Parasitic elements are selectively placed near specific dipole elements (first and second dipoles) but not others, creating local variations in electromagnetic coupling. This local quality adjustment optimizes the circular polarization characteristics at specific regions of the antenna, improving overall polarization purity while maintaining a small total footprint area.
3Length of stationary object
If low profile design is used, then height is reduced, but bandwidth deteriorates
Solution Approach 1:
The bandwidth is extended through segmentation into multiple dipole elements operating at different resonant frequencies. The first and second dipoles resonate at one frequency while the third and fourth dipoles resonate at another frequency, creating a multi-band operational capability. This segmented approach allows the low-profile antenna to achieve wide bandwidth by combining the frequency responses of multiple elements.
Solution Approach 2:
The antenna structure serves multiple functions simultaneously: it provides low-profile geometry for compact integration, achieves wide bandwidth through multi-frequency resonance of different dipole elements, and maintains circular polarization capability. The parasitic elements add the function of impedance matching and bandwidth enhancement without significantly increasing the antenna height, making the structure universally applicable to space-constrained applications requiring broadband operation.
4Adaptability or versatility
If multi-band operation is implemented, then adaptability to multiple GNSS systems is improved, but device complexity increases
Solution Approach 1:
Multiple functional elements (four dipole elements and parasitic elements) are merged into a single integrated antenna structure that operates across multiple frequency bands. Instead of using separate antennas for different GNSS systems, the merged structure achieves multi-band operation through the combined resonance of its elements, reducing the number of discrete components and simplifying the overall system while maintaining adaptability to multiple GNSS standards.
Solution Approach 2:
The antenna structure is designed with universal multi-functionality to support multiple GNSS systems (GPS, GLONASS, Galileo, BeiDou) operating at different frequencies. The same physical structure, with its multi-resonant dipole elements, can simultaneously or sequentially operate across L1, L2, L5, and other frequency bands, eliminating the need for system-specific antenna designs and reducing overall device complexity.
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 wider bandwidth, improved gain, and reduced axial ratio at low elevations, enhancing the antenna's performance in terms of radiation pattern uniformity and polarization purity, making it suitable for diverse GNSS applications while maintaining a compact and lightweight form factor.
Implementation Method 1
each of the first antenna element and the second antenna element comprise: a dipole comprising a first element and a second element; a feed point coupled to a first end of the first element and a first end of the second element; a parasitic element disposed parallel to the dipole
Data Source
AI summary
Competing tradeoffs of overall footprint, weight, and performance impact the design of antennas for many applications. However, those for compact portable devices or mobile platforms exploiting global navigation satellite systems these are further compounded by seeking good performance over a wide angular range. Accordingly, it would be beneficial to provide designers of a wide range of electrical devices and systems with compact broadband antennas which offer a low vertical profile relative to that provided by the common filar element approaches for high precision applications. Accordingly, through a combination of a dipole, a parasitic element, and additional ground elements to a convention ground plane the inventors provide broadband high performance antenna designs with low profile and low overall footprint.