Bent Feed Stalk Base Station Antennas for Symmetric Multi-Band Arrays

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Solution Overview

Problem

Existing base station antennas face challenges in achieving a 65° azimuth HPBW while adhering to commercial width limits and supporting multiple frequency bands, particularly with the introduction of 5G services, due to constraints on the number of deployable antennas and the need for multi-column arrays.

Innovation Solution

The design incorporates bent feed stalks coupled to side support segments and radiating elements, positioning them away from the side walls, and uses a single feed stalk for cross-polarized dipole arms, along with a frequency selective surface and printed circuit boards to enhance antenna performance and reduce passive intermodulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If linear arrays of wide-band radiating elements are used to support new frequency bands, then multi-band service capability is improved, but the number of deployable antennas is limited due to width constraints

Engineering Contradiction:

Improvemulti-band service capabilityVSAvoidantenna width

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent transitions from traditional front-fed radiating elements to side-fed radiating elements, changing the feeding dimension from the front face to the side wall of the antenna. This dimensional change allows the antenna to support multiple frequency bands without increasing the front width, as the feed structures are now arranged along the side walls where space is more readily available.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent divides the antenna structure into multiple side walls, each potentially carrying different feed structures and radiating elements for different frequency bands. This segmentation allows independent optimization of each band's feed path without interfering with other bands, enabling multi-band operation within width constraints.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If multiple linear arrays are deployed to support 5G services, then beamforming and massive MIMO capabilities are improved, but the number of antennas exceeds deployment limits

Engineering Contradiction:

Improvebeamforming and massive MIMO capabilityVSAvoidnumber of antennas

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent designs a single antenna structure that can simultaneously support traditional wide-band services and 5G beamforming/massive MIMO services by incorporating multiple linear arrays with different feeding configurations. The side-fed architecture provides the structural flexibility needed to accommodate multiple functional requirements within one antenna unit.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges multiple linear arrays into a single integrated antenna structure, combining legacy service support and 5G service support in one deployment. This merging reduces the total number of separate antenna units needed while maintaining all required functionalities.

Inventive Principle:

Principle #5Merging (Combining)

3Area of stationary object

If radiating elements are positioned close to side walls to reduce width, then area utilization is improved, but antenna pattern symmetry deteriorates

Engineering Contradiction:

Improveantenna widthVSAvoidantenna pattern symmetry

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent intentionally introduces asymmetry in the feed structure placement (side-fed rather than front-fed) to achieve an overall symmetric radiation pattern. By positioning feeds on opposite side walls in a balanced configuration, the asymmetric local feed positions produce symmetric far-field radiation characteristics, resolving the contradiction between compact width and pattern symmetry.

Inventive Principle:

Principle #4Asymmetry

4Reliability

If feed stalks are extended to reach radiating elements, then electrical connection is improved, but passive intermodulation increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidpassive intermodulation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the feed stalks from the traditional front-fed position and relocates them to side-fed positions, separating the feed structures from the main radiation aperture. This extraction reduces the interaction between feed stalks and radiating elements that causes passive intermodulation, while maintaining reliable electrical connection through the side-fed configuration.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20250323426A1Base station antennas with radiating elements having bent feed stalks and side feed

Publication Date: 2025.10.16 OUTDOOR WIRELESS NETWORKS LLC

AI summary

Radiating elements of first and second linear arrays of radiating elements have respective feed stalks that project laterally inward from side feeds, then bend at a 90 degree angle to project forward and provide a balanced dipole arm.