Embedded Antenna Branch Reactance Multiband Design
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Solution Overview
Problem
Existing embedded antennas in mobile terminals face challenges with deteriorated radiation efficiency, narrow bandwidth, and difficulty in achieving wideband and multiband characteristics due to limited size and low resistance characteristics, which complicates their miniaturization and multifunctionality.
Innovation Solution
The integration of branch reactances and stubs with the rear case of a mobile terminal to form multiple current paths and resonant frequency bands, utilizing capacitive elements and adjustable stub lengths and widths to control resonant frequencies and expand bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inverted-F antenna is used as an embedded antenna, then the antenna can be easily fabricated and installed, but the radiation efficiency and bandwidth are deteriorated
Solution Approach 1:
The antenna is divided into multiple segments including a radiator, first branch arm, second branch arm, first stub, and second stub. Each segment serves a specific function in creating multiple current paths and resonant frequency bands, allowing the antenna to achieve multiband characteristics while maintaining ease of fabrication through simple structural components
Solution Approach 2:
The antenna structure incorporates adjustable parameters such as the lengths and widths of stubs and branch arms, which can be dynamically modified to control resonant frequencies and impedance matching. This dynamic adjustability enables the antenna to achieve wideband and multiband characteristics while maintaining ease of manufacture
2Volume of moving object
If the antenna size is limited due to installation in small space, then the antenna can be installed in mobile terminal, but the input impedance has great capacitive reactance with low resistance
Solution Approach 1:
The antenna structure employs a nested configuration where stubs are positioned within or adjacent to the radiator and branch arms, creating multiple current paths in a compact arrangement. This nesting allows the antenna to achieve complex impedance characteristics and multiband operation within a limited volume suitable for mobile terminal installation
Solution Approach 2:
The antenna utilizes three-dimensional spatial arrangement of stubs and branch arms extending in different directions from the radiator. This dimensional approach allows the creation of multiple resonant frequency bands and improved impedance characteristics without increasing the overall footprint, enabling compact installation while maintaining reliable electrical performance
3Reliability
If matching circuit is used to remove reactance, then the inverted-F antenna can be matched, but the antenna has narrowband characteristics rather than wideband characteristics
Solution Approach 1:
Instead of using a traditional matching circuit, the antenna is segmented into multiple functional parts (radiator, branch arms, stubs) that collectively provide both impedance matching and wideband operation. Each segment contributes to creating multiple current paths with different electrical lengths, achieving matching across wide frequency ranges without limiting bandwidth
Solution Approach 2:
The stubs and branch arms serve multiple functions simultaneously: they provide impedance matching, create additional resonant frequency bands, and expand the overall bandwidth. This multi-functionality eliminates the need for separate matching circuits that would otherwise limit bandwidth, achieving both reliable matching and wideband characteristics in a single integrated structure
4Device complexity
If low-resistance characteristics are present, then the antenna can be simple in structure, but the radiation efficiency is decreased
Solution Approach 1:
The antenna structure incorporates adjustable parameters such as stub lengths, branch arm dimensions, and gap sizes that can be dynamically optimized to achieve high radiation efficiency. These dynamic design parameters allow the antenna to maintain simple construction while achieving low input reactance and high radiation efficiency through proper geometric optimization rather than complex circuitry
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 enhances the antenna's ability to achieve multiband and wideband characteristics by expanding resonant frequency bandwidth and improving radiation efficiency, effectively addressing the limitations of traditional embedded antennas.
Implementation Method 1
the first and second branch reactances include a capacitive element. The capacitive element include a chip capacitor
Implementation Method 2
The first branch reactance and the second branch branch reactance form a plurality of current paths to generate a plurality of resonant frequency bands
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An antenna according to an embodiment includes a substrate; a radiator; a ground plane spaced apart from the radiator; a feeding pin for feeding an RF signal; a first branch reactance at one side of the feeding pin, the first branch reactance including one end connected to the substrate and an opposite end connected to the ground plane; and a second branch reactance at an opposite end of the feeding pin, the second branch reactance including one end connected to the substrate and an opposite end connected to the ground plane.