Multiband Antenna with Segmented Branches and Impedance Matching
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Solution Overview
Problem
There is a need for compact antennas that can efficiently operate across multiple frequency bands, particularly in small wireless communication terminals, while maintaining performance across various frequency ranges without significant degradation.
Innovation Solution
The design incorporates a multiband RF antenna structure with specific antenna branches and impedance matching elements, including a coaxial RF feed structure and inductive matching elements, to resonate across frequencies from 824 MHz to 960 MHz and 1710 MHz to 2700 MHz, ensuring efficient operation across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If antenna size is reduced to fit small wireless terminals, then terminal compactness is improved, but antenna performance across multiple frequency bands deteriorates
Solution Approach 1:
The antenna is divided into multiple separate antenna branches (first antenna branch, second antenna branch, third antenna branch) with different lengths. Each branch is tuned to resonate at different frequency bands, allowing the compact antenna structure to achieve multiband operation by combining the resonance characteristics of individual segmented branches.
Solution Approach 2:
Different portions of the antenna structure are designed with different electrical characteristics. The feed conductor has a first impedance, the ground conductor has a second impedance, and impedance matching elements are strategically placed to provide localized impedance transformation. This local quality variation enables each branch to be optimized for specific frequency ranges while maintaining overall compactness.
2Ease of manufacture
If antenna structure is simplified for manufacturing, then ease of manufacture is improved, but impedance matching performance across frequency bands deteriorates
Solution Approach 1:
Impedance matching elements are introduced as intermediary components between the feed conductor and the antenna branches. These elements serve as mediators to transform and match impedances across different frequency bands, ensuring reliable impedance matching without requiring complex antenna geometries that would be difficult to manufacture.
Solution Approach 2:
The impedance characteristics of the antenna system are controlled by adjusting parameters such as conductor dimensions, spacing between conductors, and the properties of impedance matching elements. By changing these physical parameters, the antenna achieves proper impedance matching across multiple frequency bands while maintaining a simple, manufacturable structure.
3Volume of moving object
If antenna branches are coupled closely to ground conductor, then compactness is improved, but electromagnetic interference between branches increases
Solution Approach 1:
The ground conductor is designed with specific impedance characteristics and is coupled to each antenna branch at controlled distances. This creates equipotential regions that reduce unwanted electromagnetic coupling between branches while maintaining compact overall dimensions. The ground conductor acts as a reference that stabilizes the electromagnetic environment for each branch.
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 allows for compact, efficient, and effective operation across multiple frequency bands, including GSM, DCS, GPS, and Bluetooth frequencies, with improved impedance matching and resonance performance, maintaining high-bandwidth capabilities without impacting low-band frequencies.
Implementation Method 1
Each antenna branch is electrically connected to the feed conductor and the ground conductor... resonate across frequencies from 824 MHz to 960 MHz and 1710 MHz to 2700 MHz
Implementation Method 2
inductive matching elements... improved impedance matching and resonance performance
Data Source
Figure 1
Figure 2A~2D
Figure 3~4B
AI summary
A communications structure may include a ground plane, a ground conductor electrically coupled to the ground plane and extending from the ground plane, and a feed conductor. A first antenna branch may be electrically coupled to the ground conductor, with an electrical coupling between the first antenna branch and the ground conductor being spaced apart from an electrical coupling between the ground plane and the ground connector. A second antenna branch may be electrically coupled to the feed conductor, with the first and second antenna branches being spaced apart. In addition, a radio frequency (RF) transmitter and/or receiver may be provided with the ground plane and the feed conductor being electrically coupled to the RF transmitter and/or receiver.