Microstrip Filter Feeding Network for Base-Station Antennas
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Solution Overview
Problem
Conventional filter designs for remote radio units in base stations are large, heavy, and difficult to integrate with antennas, limiting their application in high-density MIMO active antenna systems.
Innovation Solution
A filter feeding network utilizing a dielectric substrate with microstrip lines and metal ground, incorporating power division circuits and filters, including low-pass and band-pass filters, to create a compact and lightweight solution suitable for large-scale production, integrating with microstrip power dividers to simplify RF unit structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coaxial or air cavity filters are used in RRU, then filtering function is achieved, but filter size and weight become large, making integration with antenna difficult
Solution Approach 1:
The patent replaces conventional mechanical coaxial or air cavity filters with a microstrip-based distributed element filter. The filtering function is achieved through distributed inductive and capacitive elements formed by microstrip lines on a substrate, eliminating the need for heavy mechanical filter structures while maintaining the required filtering performance.
Solution Approach 2:
The patent changes the physical implementation parameters of the filter from volumetric mechanical structures to planar microstrip transmission lines. By transforming the filter into a distributed element configuration with specific impedance values and line lengths, the filter achieves the same electrical characteristics with dramatically reduced weight and size.
2Reliability
If conventional coaxial or air cavity filters are used in RRU, then filtering function is achieved, but filter volume becomes large, making integration with antenna difficult
Solution Approach 1:
The patent replaces conventional mechanical coaxial or air cavity filters with a microstrip-based distributed element filter. The filtering function is achieved through distributed inductive and capacitive elements formed by microstrip lines on a substrate, eliminating the need for heavy mechanical filter structures while maintaining the required filtering performance.
Solution Approach 2:
The patent transitions the filter design from three-dimensional volumetric structures to two-dimensional planar microstrip patterns on a substrate. This dimensional reduction allows the filter to be integrated directly into the antenna feed network plane, dramatically reducing the overall volume while maintaining filtering functionality.
3Reliability
If RRU with passive modules is used, then filtering and amplification functions are achieved, but device complexity and installation difficulty increase
Solution Approach 1:
The patent merges the filter and power divider functions into a single integrated microstrip-based feeding network. The distributed element filter and power division circuits are implemented together on the same substrate using microstrip lines, eliminating the need for separate passive modules and reducing overall device complexity.
Solution Approach 2:
The microstrip feeding network structure serves multiple functions simultaneously: it provides filtering, power division, and impedance transformation all within a single integrated configuration. This multi-functionality eliminates the need for separate dedicated components for each function, simplifying the overall RRU structure.
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 solution achieves a highly integrated, lightweight filter feeding network that simplifies RF unit structures, reduces volume and weight, and enhances system integration, while improving outband suppression and supporting high-order harmonic wave filtering.
Implementation Method 1
a surface of one side of the dielectric substrate is provided with a microstrip line
Implementation Method 2
including a dielectric substrate, where a surface of one side of the dielectric substrate is provided with a microstrip line
Implementation Method 3
a surface of the other side of the dielectric substrate is provided with a metal ground
Implementation Method 4
the microstrip line includes first and second power division circuits, and first and second filter circuits
Implementation Method 5
first and second filter circuits; an input end and an output end of the first filter circuit are respectively connected to an input end and an output end of the first power division circuit correspondingly
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Provided is a filter feeding network, including a dielectric substrate (1), where a surface of one side of the dielectric substrate (1) is provided with a microstrip line (2), and a surface of the other side of the dielectric substrate (1) is provided with a metal ground (3); the microstrip line (2) includes first and second power division circuits (21, 21'), and first and second filter circuits (220, 220'); an input end and an output end of the first filter circuit (220) are respectively connected to an input end and an output end of the first power division circuit (21) correspondingly, an input end and an output end of the second filter circuit (220') are respectively connected to an input end and an output end of the second power division circuit (21') correspondingly, and the input end of the first filter circuit (220) and the input end of the second filter circuit (220') are in conduction with the metal ground (3); and the output end (212) of the first power division circuit (21) feeds at least two array antenna units for -45° polarization, and the output end (212') of the second power division circuit (21') feeds at least two array antenna units for +45° polarization. The present invention further provides a base station antenna. The filter feeding network is highly integrated, has a small weight and a small volume, and is suitable for large-scale production.