Multi-Resonant Antenna Impedance Matching via Segmented Sub-Elements
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Solution Overview
Problem
Existing antenna devices with multiple resonant frequencies and broad frequency ranges face challenges in maintaining necessary impedance characteristics, leading to size and thickness issues, particularly in compact devices like notebooks, and can suffer from impedance mismatch when constrained in size.
Innovation Solution
The antenna device incorporates a printed board with a ground conductor, a first sub-element crossing another, a second sub-element branching off and directed oppositely, and a short circuit element that short-circuits one of these with the ground conductor, optimizing impedance characteristics across a 2-8 GHz frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the antenna uses a narrow strip shaped element with arc shaped portion and projection for impedance adjustment, then the frequency range is broadened, but the size of the antenna in the direction perpendicular to the ground plate increases
Solution Approach 1:
The antenna element is divided into multiple segments including a first sub-element, a second sub-element, and a short circuit element. Each segment serves a specific function in achieving broadband operation while controlling the overall size. The first sub-element provides the main radiating structure, the second sub-element extends the frequency range, and the short circuit element controls impedance without requiring additional space perpendicular to the ground plate.
Solution Approach 2:
Instead of increasing the antenna size in the direction perpendicular to the ground plate, the invention utilizes the planar dimension parallel to the ground plate more effectively. The multiple sub-elements are arranged in a configuration that exploits the two-dimensional space on the printed board, transforming the problem from a three-dimensional size constraint to a two-dimensional layout optimization.
2Length of stationary object
If the antenna is constrained to insufficient size in the direction perpendicular to the ground conductor, then the device becomes compact, but impedance mismatch occurs due to decreased impedance at feed portions
Solution Approach 1:
The invention applies different structural characteristics to different parts of the antenna. The first sub-element has a specific width and shape optimized for the lower frequency range, while the second sub-element has different dimensions optimized for the upper frequency range. The short circuit element is positioned and sized to provide the necessary impedance transformation locally at the feed portion, ensuring proper impedance matching without requiring the entire antenna to be large.
Solution Approach 2:
The invention changes the electrical parameters of the antenna by introducing the short circuit element, which transforms the impedance characteristics. By adjusting the position, width, and length of the short circuit element and the two sub-elements, the impedance at the feed portion can be controlled to match the desired value, maintaining reliability even in compact configurations.
3Adaptability or versatility
If the antenna uses a triple layered fan shaped structure, then multiple resonant frequencies are achieved, but the antenna thickness increases and layers need alignment
Solution Approach 1:
The invention extracts the essential function of achieving multiple resonant frequencies from the complex triple-layered structure and implements it using a simplified two-sub-element configuration. By taking out only the necessary elements (first sub-element, second sub-element, and short circuit element) and removing unnecessary layers, the invention achieves the same multi-frequency capability with reduced structural complexity and easier manufacturing.
Solution Approach 2:
Instead of building up multiple layers to achieve multiple frequencies, the invention inverts the approach by using a planar configuration with elements of different lengths and positions. Rather than stacking layers vertically, the solution spreads the frequency-determining elements horizontally across the printed board, simplifying the structure and eliminating alignment requirements between layers.
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 enhances impedance matching and radiation efficiency while maintaining a compact size, improving performance in both lower and higher frequency ranges without significantly affecting the resonant frequencies.
Implementation Method 1
a short circuit element that short-circuits one of the first sub-element and the second sub-element with the ground conductor
Implementation Method 2
an antenna device having multiple resonant frequencies or a broad frequency range
Implementation Method 3
improving performance in both lower and higher frequency ranges without significantly affecting the resonant frequencies
Data Source
AI summary
An antenna device included in a radio apparatus having a printed board includes a ground conductor provided in the printed board, a first sub-element, a second sub-element and a short circuit element. The first sub-element is formed as an area having a first side and a second side crossing each other. The first side faces a side of the ground conductor. The first sub-element has a feed portion around a crossing of the first side and the second side. The second sub-element is formed to branch off from the first sub-element around an end of the second side being farther from the crossing, to be open-ended and to be directed at least partially in a direction opposite a direction from the crossing to an end of the first side opposite the crossing. The short circuit element short-circuits one of the first sub-element and the second sub-element with the ground conductor.