Base Station Antenna Choke Assemblies for Radiation Pattern Control
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Solution Overview
Problem
Base station antennas face challenges in improving azimuth beam width, azimuth pattern roll-off, front-to-back ratio, and cross polarization ratio, especially when radiating elements are mounted close to the edges of the reflector, leading to poor radiation patterns.
Innovation Solution
The implementation of a reflector with choke-within-a-choke assemblies, including multiple chokes of varying configurations and dimensions on the rear surface, which extend between the rearwardly projecting sidewalls, and a raised rigidity-enhancing rib, to manage RF energy and enhance radiation patterns without increasing the overall width of the reflector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If radiating elements are mounted close to the edges of the reflector to maximize antenna width utilization, then the antenna can support more columns and frequency bands, but the radiation patterns deteriorate with poor azimuth beam width, roll-off, front-to-back ratio, and cross polarization ratio
Solution Approach 1:
The patent implements choke-within-a-choke assemblies where multiple chokes of different sizes are nested within each other on the rear surface of the reflector. This nesting arrangement allows multiple chokes to be integrated without increasing the overall reflector width, enabling the radiating elements to be positioned close to the edges while maintaining good radiation patterns through the combined choking effect of the nested structures.
Solution Approach 2:
The patent moves the choke structures from the front surface to the rear surface of the reflector, utilizing the unused rear surface area to implement multiple chokes. This dimensional relocation allows the chokes to affect the radiation patterns without occupying space on the front surface where radiating elements need to be positioned for maximum width utilization.
2Reliability
If multiple chokes are added to improve radiation patterns, then azimuth beam width, roll-off, front-to-back ratio, and cross polarization ratio improve, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The nested choke configuration allows multiple chokes to share common boundaries and structures. The chokes are arranged concentrically with smaller chokes inside larger ones, sharing portions of their perimeters and reducing the total amount of material and structural support needed compared to separate, non-nested choke arrangements.
Solution Approach 2:
The nested choke assemblies serve multiple functions simultaneously: they control radiation patterns, provide structural support for the reflector rear surface, and can be integrated with the mounting structure for radiating elements. This multi-functionality reduces the need for additional separate components, simplifying the overall device complexity.
3Adaptability or versatility
If the reflector width is increased to accommodate more radiating elements, then more columns and frequency bands can be supported, but the overall antenna size and structural requirements increase
Solution Approach 1:
The patent utilizes the rear surface of the reflector, which is typically unused space, to implement the choke structures. By relocating the chokes from the front surface to the rear surface, the design maximizes the utilization of the existing reflector width without requiring any increase in the overall antenna dimensions.
Solution Approach 2:
The nested choke configuration allows multiple chokes to be packed into a compact area on the rear surface of the reflector. This nesting arrangement enables the inclusion of multiple chokes for controlling radiation patterns across different frequency bands without expanding the reflector width, as the chokes share common boundaries and occupy overlapping spatial regions.
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 configuration improves the azimuth beam width, roll-off, front-to-back ratio, and cross polarization ratio, enabling more efficient radiation patterns and structural integrity for multi-column, multi-band applications.
Implementation Method 1
As the RF signals at the top of the outer side of the U-shaped channels 16a, 16b of the RF chokes 12a, 12b are about 180° out-of-phase with the RF signals at the top of the inner side of U-shaped channels 16a, 16b, these phase-shifted signals tend to cancel each other so that interfering radiation from opposing sides of the reflector 10 can be advantageously suppressed.
Implementation Method 2
the front 14a of the reflector 10 acts as the main reflective surface 20 for redirecting RF energy to the forward direction
Data Source
AI summary
A base station antenna (BSA) includes a reflector having a main reflector surface thereon, which extends between first and second sidewalls thereof. First and second choke-within-a-choke assemblies are provided on first and second sides of the reflector, respectively. The first choke-within-a-choke assembly includes: a first relatively low-band choke defined on one side thereof by the first sidewall of the reflector, and a first relatively high-band choke contacting on two sides thereof a rear surface of the reflector and an inner surface of the first sidewall. The second choke-within-a-choke assembly includes: a second relatively low-band choke defined on one side thereof by the second sidewall of the reflector, and a second relatively high-band choke contacting on two sides thereof the rear surface of the reflector and an inner surface of the second sidewall.