Circularly Polarized Phased-Array Super-Elements for Wide Scanning
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Solution Overview
Problem
Conventional circularly-polarized antennas face challenges in maintaining an axial ratio close to 0 dB as scanning angles increase, making it difficult to achieve wide scanning ranges, particularly in 5G mm-wave applications.
Innovation Solution
The design incorporates four sequentially fed antenna patches as a super-element with orthogonal polarizations and parasitic transmission lines to enforce field vectors, achieving an axial ratio below 3.6 dB for scanning angles of at least 75 degrees at 39.5 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional circularly-polarized antennas are used, then the axial ratio can be maintained close to 0 dB at broadside, but the scanning range is limited as scanning angles increase
Solution Approach 1:
The antenna element is divided into four sequentially fed patches arranged in a specific geometry, each patch contributing to different polarization components. This segmentation allows independent control of field vectors to maintain circular polarization characteristics across wide scanning angles
Solution Approach 2:
Parasitic transmission lines are introduced as intermediary elements that enforce orthogonal field vectors between the fed patches. These parasitic structures mediate the electromagnetic coupling to maintain the required phase and amplitude relationships for circular polarization during beam scanning
2Ease of operation
If phased array antennas are used to achieve directional steering, then beam focusing capability is improved, but the complexity of the system increases
Solution Approach 1:
The antenna design incorporates dynamically adjustable phase shifters and amplitude controllers that allow real-time beam steering without mechanical movement. The sequentially fed patches with controlled phase differences enable electronic beam forming and directional steering through dynamic phase modulation
Solution Approach 2:
Multiple antenna patches are merged into a single super-element that inherently provides both circular polarization and beam steering capabilities. The combined structure integrates what would traditionally require separate components, reducing overall system complexity while maintaining directional control
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
This design enables circularly-polarized antennas with wide scanning ranges, enhancing performance in 5G communications by maintaining low axial ratios and improving signal quality.
Implementation Method 1
an antenna element includes four sequentially fed patches arranged in a specific geometry to generate orthogonal field vectors
Implementation Method 2
parasitic transmission lines that enforce orthogonal field vectors
Data Source
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Figure 2B
AI summary
New antenna designs for realizing circularly-polarized antennas with a wide scanning range are disclosed. The designs are based on arranging four sequentially fed antenna patches to be considered as a single antenna element, referred to as a "super-element," in the overall phased array. An example super-element includes relatively short transmission lines to provide excitations for the vertically and horizontally polarized fields, with the transmission lines for the vertically and horizontally polarized fields being perpendicular to one other. A parasitic transmission line may be placed around a part of each antenna patch of the super-element to serve as a coupler to further enforce the field vector direction for keeping the circular polarization. With such designs, an axial ratio below 3.6 dB for scanning angles of at least 75 degrees at 39.5 GHz may be achieved.