Dual Antenna Support and Isolation Enhancer for Cross-Polarized Arrays
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Solution Overview
Problem
Existing antenna systems with collocated antennas face challenges in achieving sufficient isolation, leading to reduced coverage area, antenna efficiency, and lower than desired decoupling, especially when closely spaced and cross-polarized, with known solutions often requiring large physical separation or being compromised by scatterers and material discontinuities.
Innovation Solution
A dual antenna support and isolation enhancer that electrically connects the coaxial cable shield to a ground plane, incorporates short-circuited LC resonators, and uses support tabs and loading pins to enhance isolation between cross-polarized antennas, allowing for improved decoupling and reduced current flow, thereby increasing isolation to 60 dB over a specific frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If known isolation techniques are used to isolate collocated antennas, then antenna isolation is improved, but coverage area is reduced due to compromise of far-field patterns and/or reduction in antenna efficiency
Solution Approach 1:
A ground plane with specific geometric features (discontinuous ground structure, frequency selective surface, or RF absorber) is introduced as an intermediary element between the two collocated antennas. This intermediary structure selectively interacts with electromagnetic fields to provide isolation in specific directions while preserving far-field radiation patterns and overall antenna efficiency, thereby maintaining coverage area.
Solution Approach 2:
The ground plane structure is designed with spatially varying properties - certain regions have discontinuities or absorptive materials to provide isolation where needed, while other regions maintain continuous ground plane characteristics to preserve radiation patterns. This local differentiation allows simultaneous achievement of isolation and coverage.
2Object-affected harmful factors
If known isolation techniques are used to isolate collocated antennas, then antenna isolation is improved, but physical separation between antenna elements must be large which is not feasible for integrated antennas
Solution Approach 1:
The ground plane with isolation-enhancing features serves as a mediator that enables high isolation (60 dB or greater) between closely-spaced antennas. By placing this intermediary structure on the ground plane beneath or between the antennas, the need for large physical separation is eliminated while achieving the required isolation for concurrent radio operation.
3Object-affected harmful factors
If scatterers and/or material discontinuities are introduced to improve isolation, then antenna isolation is improved, but free-space radiation patterns are severely degraded
Solution Approach 1:
The ground plane is designed with discontinuities or absorptive materials only in specific localized regions where they provide isolation benefits without interfering with the main radiation lobes. The majority of the ground plane remains continuous to preserve the overall radiation pattern shape and far-field characteristics.
Solution Approach 2:
The ground plane structure acts as an intermediary that provides isolation through controlled interactions (reflection, absorption, or resonance) in specific directions, while allowing free-space radiation patterns to remain largely unaffected in the desired coverage directions.
4Adaptability or versatility
If cross-polarized omnidirectional antennas are closely spaced, then integration is improved, but isolation is only around 35 dB which is much lower than the preferred 60 dB
Solution Approach 1:
A ground plane with specific geometric features (discontinuous ground structure, frequency selective surface, or RF absorber) is introduced as an intermediary element between the two collocated antennas. This intermediary structure selectively interacts with electromagnetic fields to provide isolation in specific directions while preserving far-field radiation patterns and overall antenna efficiency, thereby maintaining coverage area.
Solution Approach 2:
The ground plane parameters (geometry, material properties, discontinuity patterns, or absorptive characteristics) are optimized to achieve 60 dB or greater isolation across the operating frequency range. By carefully controlling these parameters, high isolation is achieved without compromising the cross-polarized omnidirectional antenna configuration or its integration benefits.
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 dual antenna support and isolation enhancer significantly improves antenna isolation by up to 17 dB, maintaining efficiency and radiation pattern performance, while being cost-effective and feasible for integrated antenna designs.
Implementation Method 1
incorporates short-circuited LC resonators
Implementation Method 2
electrically connects the coaxial cable shield to a ground plane, incorporates short-circuited LC resonators, and uses support tabs and loading pins to enhance isolation
Data Source
AI summary
Embodiments disclosed herein include an antenna assembly that includes a dual antenna support and isolation enhancer coupled to a first antenna element for isolating the first antenna element relative to a collocated, vertically-polarized antenna element. The dual antenna support and isolation enhancer can include tabs to support the first antenna element and shield a coaxial cable feeding the first antenna element, a base electrically connected to a shield of the coaxial cable for shorting to ground induced current on the shield of the coaxial cable, and, in some embodiments, at least one of a plurality of loading pins that can form a short-circuited LC resonator that can effectively open-circuit a gap of a coplanar strip transmission line that routes to a feed connection point of the first antenna element when vertically-polarized radiation is incident on the antenna assembly.