Interleaved Small Cell Antenna Arrays for High-Band Isolation
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Solution Overview
Problem
Existing multiband multiport omni-directional antennas for small cell base stations face challenges in maintaining signal integrity and reducing unwanted radiation patterns due to the presence of lower frequency band arrays, which affect the performance of higher frequency band arrays.
Innovation Solution
The proposed solution involves interleaving high and very high band arrays horizontally on a single structure using polygon prisms or cylinders for reflectors, and employing waveguiding metal plates with equal dimensions to make lower band arrays 'invisible' to higher band arrays, thereby reducing the negative impact of lower band structures on higher band patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If lower frequency band arrays are stacked below higher frequency band arrays to achieve compact antenna design, then antenna size is reduced, but unwanted re-radiation from lower band structures degrades the radiation pattern of higher band arrays
Solution Approach 1:
A waveguiding metal plate is introduced as an intermediary structure between the lower BAND-2 array and the higher BAND-3 and BAND-4 arrays. This plate acts as a mediator that blocks unwanted electromagnetic interactions from the lower band structures, preventing harmful re-radiation effects while allowing the compact stacked configuration to be maintained. The plate is positioned horizontally above the lower band array and below the higher band arrays, creating an electromagnetic barrier that isolates the higher frequency elements from the lower frequency structures.
Solution Approach 2:
The harmful lower band structures (BAND-2 array and its reflector) are effectively extracted or removed from the electromagnetic environment of the higher band arrays by placing the waveguiding metal plate between them. This extraction prevents the lower band structures from inducing unwanted currents and re-radiating signals that would degrade the higher band radiation patterns, while the physical space is still occupied to maintain compact antenna size.
2Adaptability or versatility
If lower frequency band arrays with larger structures are placed below higher frequency band arrays, then multi-band functionality is achieved in compact space, but beam peak misalignment and elevated side lobe levels occur for higher band arrays
Solution Approach 1:
The waveguiding metal plate serves as an intermediary that prevents the larger lower band structures from causing beam peak misalignment and elevated side lobe levels in the higher band arrays. By blocking the electromagnetic coupling between bands, the plate ensures that each frequency band operates with its intended radiation pattern characteristics, maintaining precision in beam alignment and side lobe control while achieving multi-band functionality.
Solution Approach 2:
The waveguiding metal plate is strategically positioned only in the region where harmful electromagnetic interactions occur between the lower and higher band arrays. This localized intervention preserves the multi-band functionality throughout the antenna structure while specifically addressing the local quality issues of beam alignment and side lobe levels in the higher band regions without affecting the overall compact design.
3Volume of moving object
If lower band arrays are positioned close to higher band arrays to reduce antenna volume, then compactness is achieved, but induced currents on lower band structures cause pattern degradation and increased side lobe levels
Solution Approach 1:
The waveguiding metal plate is positioned as an intermediary barrier between the lower and higher band arrays, preventing the close proximity from causing harmful induced currents. The plate blocks the electromagnetic fields that would otherwise induce currents on the lower band structures, thereby preventing re-radiation and pattern degradation while allowing the antenna to maintain its compact volume through the stacked configuration.
Solution Approach 2:
The harmful induced currents and re-radiation effects are effectively extracted or removed from the system by introducing the waveguiding metal plate. This plate eliminates the unwanted electromagnetic coupling that would cause current induction on lower band structures, thereby removing the harmful effects while preserving the compact stacked arrangement of multi-band arrays.
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 significantly reduces the effect of lower frequency array structures on higher frequency radiators, improving elevation patterns and gain of higher frequency band arrays while meeting FCC regulations for Side Lobe Level (SLL).
Implementation Method 1
waveguiding metal plates with equal dimensions to make lower band arrays 'invisible' to higher band arrays
Implementation Method 2
The reflector plates of the at least one second array are interspersed between the reflector plates of the at least one third array such that the reflector plates of the second and third arrays alternate around the circumference of the upper portion of the antenna
Data Source
AI summary
An omni-directional small cell base station antenna includes at least one array of a first frequency on a lower portion of the antenna, at least one second array of a second frequency on an upper portion of the antenna, and at least one third array of a third frequency on the upper portion of the antenna. The second frequency is higher than the first frequency, and the third frequency is higher than the second frequency. The at least one second array at a second frequency includes a plurality of reflector plates with antenna elements of the second frequency thereon, and the at least one third array at a third frequency includes a plurality of reflector plates with antenna elements of the third frequency thereon. The reflector plates of the at least one second array are interspersed between the reflector plates of the at least one third array such that the reflector plates of the second and third arrays alternate around the circumference of the upper portion of the antenna.