Multi-band Antenna Design for High Efficiency and Isolation
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Solution Overview
Problem
Existing multi-band antennas for mobile radio communication terminals face challenges in achieving high antenna efficiency and isolation between radiating elements, often resulting in increased costs and decreased reliability due to the number of terminal electrodes and inefficient radiation resistance.
Innovation Solution
The antenna design incorporates a first radiating element resonating in a ¼ wavelength mode and a second radiating element resonating in a ½ wavelength mode, with a shared ground point and a feed line connecting between the feed and ground points, optimizing the distance from the ground to the feed points to enhance radiation resistance and reduce the number of terminal electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a folded structure with ground point near feed point is used for λ/4 mode antenna element, then the antenna structure is compact, but the loop diameter becomes small, radiation resistance becomes low, and antenna efficiency deteriorates
Solution Approach 1:
The antenna system is segmented into two distinct radiating elements: a first element operating in λ/4 mode and a second element operating in λ/2 mode. This segmentation allows each element to have optimized characteristics for its operating mode, with the λ/2 element providing the necessary loop area for high radiation resistance while the λ/4 element maintains compactness.
Solution Approach 2:
The antenna system combines two different operating modes (λ/4 and λ/2) in a composite structure. The first radiating element uses a folded λ/4 configuration for compactness, while the second radiating element uses a λ/2 configuration for high radiation resistance, creating a composite multi-band antenna system that achieves both compactness and efficiency.
2Reliability
If two radiating elements have separate ground points located between feed points, then isolation between elements is improved, but the total number of terminal electrodes increases to four, leading to increased cost and decreased reliability
Solution Approach 1:
The patent merges the ground points of the two radiating elements into a single common ground point. The first and second radiating elements share this common ground connection, reducing the total terminal electrode count from four to three (two feed points plus one common ground point), while maintaining sufficient isolation between elements through proper positioning and the inherent isolation provided by the different operating modes.
Solution Approach 2:
The common ground point serves multiple functions: it provides the ground reference for both the λ/4 mode element and the λ/2 mode element simultaneously. This multi-functional ground point reduces the number of required terminal electrodes while maintaining the electrical performance needed for both operating modes.
3Device complexity
If direct feeding is used instead of capacitance feeding, then the structure is simpler, but sufficient isolation between the two radiating elements cannot be ensured
Solution Approach 1:
The patent applies different feeding approaches to different elements based on their specific requirements. The first radiating element (λ/4 mode) uses capacitance feeding through a feed line to achieve compactness and proper impedance matching, while the second radiating element (λ/2 mode) uses direct feeding at its feed point. This localized differentiation allows each element to be fed in the most appropriate manner while maintaining overall system isolation.
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 design achieves high antenna efficiency and sufficient isolation between radiating elements, reducing costs and improving reliability by increasing radiation resistance and maintaining effective performance across multiple frequency bands.
Implementation Method 1
The first radiating element is open at a first end thereof, is connected to a ground point at a second end thereof, and resonates in a substantially 1⁄4 wavelength mode in a first communication frequency band
Implementation Method 2
The second radiating element has a first end that is a second feed point, has a second end that is connected to the ground point, and resonates in a substantially 1⁄2 wavelength mode in a second communication frequency band
Data Source
AI summary
An antenna includes a base, a first radiating element, and second radiating element. The first radiating element is open at a first end thereof, is connected to a ground point at a second end thereof, and resonates in a substantially ¼ wavelength mode in a first communication frequency band. A feed line is connected between a first feed point and a predetermined position between the first end and the second end of the first radiating element. The second radiating element has a first end that is a second feed point, a second end that is connected to the ground point, and resonates in a substantially ½ wavelength mode in a second communication frequency band. A distance from the ground point to the second feed point is longer than a distance from the ground point to the first feed point.