Duplexed Base Station Antenna PIM Isolation

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Solution Overview

Problem

Base station antennas face challenges in efficiently managing multiple frequency bands, leading to passive intermodulation (PIM) distortion and complex designs that increase antenna dimensions, particularly when combining low-frequency bands like 700 MHz and 800 MHz, which can result in large antenna sizes and impractical dimensions for deployment.

Innovation Solution

The implementation of a base station antenna with separate downlink and uplink RF feed networks, using duplexers to isolate signals and bandpass filters to block PIM distortion, allowing for the segregation of downlink and uplink radiating elements into distinct arrays, thereby reducing antenna size while maintaining signal isolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple frequency bands are combined in a base station antenna, then communication versatility is improved, but passive intermodulation distortion increases and design complexity worsens

Engineering Contradiction:

Improvecommunication versatilityVSAvoidpassive intermodulation distortion

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The antenna system is segmented into separate downlink and uplink RF feed networks, with distinct radiating element arrays for each direction. This segmentation isolates the signal paths to prevent intermodulation distortion while maintaining support for multiple frequency bands through dedicated networks for each band.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The harmful intermodulation products are extracted and removed from the system by separating the downlink and uplink paths. The downlink network transmits signals while the uplink network receives signals, preventing the interaction that generates PIM distortion. Bandpass filters are also used to extract and block unwanted frequency products.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If multiple frequency bands are combined in a base station antenna, then communication versatility is improved, but antenna dimensions increase

Engineering Contradiction:

Improvecommunication versatilityVSAvoidantenna dimensions

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

Multiple radiating element arrays operating at different frequency bands are merged into a single integrated antenna structure. The arrays are positioned in close proximity and share common support structures and feeding mechanisms, allowing the antenna to support multiple bands while maintaining a compact overall dimension.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The antenna arrays for different frequency bands are nested within each other or positioned in overlapping configurations. Lower-band arrays with larger elements are nested with higher-band arrays, allowing multiple frequency bands to be accommodated in a compact space without significantly increasing overall antenna dimensions.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Device complexity

If downlink and uplink signals are combined in the same RF path, then device complexity is reduced, but signal isolation deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidsignal isolation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The RF feed network is segmented into separate downlink and uplink paths, with dedicated amplifiers, filters, and radiating element arrays for each direction. This segmentation ensures that downlink transmit signals do not interfere with uplink receive signals, providing excellent isolation while maintaining manageable system complexity through modular design.

Inventive Principle:

Principle #1Segmentation

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 solution effectively blocks PIM distortion and achieves isolation between downlink and uplink signals, enabling a compact antenna design that can accommodate multiple low-frequency bands without compromising performance, allowing for smaller antenna dimensions and improved deployment flexibility.

Implementation Method 1

a bandpass filter that is coupled to the first and second downlink RF paths

Methodology Applied

Scientific EffectBandpass filtering: Filter (electronic)

Implementation Method 2

a first duplexer that couples the first frequency band ports to a plurality of first downlink RF paths and a plurality of first uplink RF paths

Methodology Applied

Scientific EffectFrequency division multiplexing: Filter (electronic)

Implementation Method 3

a first multiplexer that couples the first and second downlink RF paths to the arrays

Methodology Applied

Scientific EffectSignal multiplexing: Filter (electronic)

Data Source

PatentUS20230170615A1Duplexed base station antennas

Publication Date: 2023.06.01 OUTDOOR WIRELESS NETWORKS LLC

AI summary

Base station antennas are provided. A base station antenna includes a plurality of arrays of radiating elements. The antenna includes a downlink radio frequency (RF) feed network that is configured to filter downlink portions of different frequency bands and that couples the filtered downlink portions of the different frequency bands to the arrays. Moreover, the antenna includes an uplink RF feed network that couples uplink portions of the different frequency bands to the arrays and that is separate from the downlink RF feed network.