Dual Circularly Polarized Antenna Array for Tx/Rx Isolation
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Solution Overview
Problem
Achieving good isolation between orthogonal polarizations and maintaining a desired axial ratio in dual circularly polarized antennas while using a simple integrated and compact design suitable for phased arrays with aggressive scanning possibilities is a significant technical challenge.
Innovation Solution
The use of orthogonally rotated and integrated dipoles with differential excitation in antenna arrays, where dipoles of receive antennas are geometrically orthogonal to dipoles of transmit antennas, improves isolation between orthogonal polarizations and co-polarizations, resulting in a stable antenna impedance during beam scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dual circularly polarized antennas are designed with orthogonal polarizations for full duplex communication, then frequency reuse and spectral efficiency are improved, but isolation between transmit and receive paths deteriorates
Solution Approach 1:
The patent applies local quality by using different polarization orientations for transmit and receive dipoles within the same antenna structure. Each dipole pair is specifically oriented to handle one polarization sense (RHCP or LHCP), creating localized functional differentiation that enables frequency reuse while maintaining isolation through polarization diversity.
Solution Approach 2:
The patent changes the polarization parameter by using orthogonal circular polarizations (RHCP and LHCP) for transmit and receive paths. This parameter change allows simultaneous operation on the same frequency band while maintaining signal isolation through the orthogonal nature of the polarizations, directly addressing both spectral efficiency and isolation requirements.
2Device complexity
If a compact integrated antenna design is used for phased arrays, then device complexity and size are reduced, but maintaining desired axial ratio and polarization purity becomes more difficult
Solution Approach 1:
The patent segments the antenna structure into distinct dipole pairs, with each pair dedicated to a specific polarization sense. This segmentation allows independent optimization of each dipole pair's geometry and feed structure, making it easier to maintain precise axial ratios and polarization purity even in a compact integrated design. Each segment can be independently tuned without affecting the other polarization channel.
Solution Approach 2:
The patent employs asymmetric feeding networks and unequal slot geometries to achieve the desired polarization characteristics. The feed lines have different lengths and impedances tailored to each dipole pair, and the slot dimensions are asymmetrically designed to produce the required current distributions for pure circular polarization. This asymmetric design enables precise control over polarization purity in the compact structure.
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 approach enhances isolation between orthogonal polarizations, improves axial ratio stability, and maintains antenna impedance stability during aggressive scanning, making it suitable for phased arrays in wireless communication systems.
Implementation Method 1
a first circularly polarized dipole antenna of an antenna array... transmitting a right hand circularly polarized signal... a second circularly polarized dipole antenna... receiving a left hand circularly polarized signal
Data Source
AI summary
Aspects of this disclosure relate to an antenna array. An antenna array may include a first circularly polarized dipole antenna that includes a first pair of conductive elements. The antenna array may include a second circularly polarized dipole antenna that includes a second pair conductive elements, the second pair of conductive elements being geometrically orthogonal to the first pair of conductive elements. The antenna array may include a beamformer integrated circuit configured to drive the second circularly polarized dipole antenna such that the second circularly polarized dipole antenna transmits a first radio frequency signal while the first circularly polarized dipole antenna receives a second radio frequency signal. The first radio frequency signal can have a different polarization and be in a different frequency band than the second radio frequency signal.