Small Antenna with Inductance Shapes for Return Loss
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Solution Overview
Problem
Existing small antennas face challenges in downsizing while maintaining improved return loss, as existing configurations struggle to effectively separate resonant frequencies and achieve satisfactory return loss when applied to downsized dipole antennas with inductance-shaped portions.
Innovation Solution
A small antenna design featuring a first element and a second element with inductance shapes, where the length from the power feeding point to the inductance shape is optimized to separate the first and second resonant frequencies, and the configuration includes a short-circuit element to adjust the resonant frequencies and improve return loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna is downsized by forming inductance shapes, then the antenna size is reduced, but the return loss deteriorates
Solution Approach 1:
The antenna element is divided into multiple sections with different shapes (inductance shapes and linear portions), where each section serves a specific function. The inductance shapes provide miniaturization while the linear portions contribute to resonant frequency control, allowing independent optimization of size and return loss characteristics
Solution Approach 2:
The patent optimizes specific parameters including the number of bending structures (3 or more), the spiral structure configurations, and the length from power feeding point to inductance shape. These parameter adjustments enable the antenna to achieve both compact size and satisfactory return loss by controlling the distribution of current and resonant frequencies
2Reliability
If the line width is adjusted to improve return loss, then the return loss is improved, but downsizing becomes difficult
Solution Approach 1:
Instead of uniformly adjusting line width across the entire antenna, the patent segments the antenna into inductance shapes and linear portions. This allows return loss optimization through geometric configuration of segmented parts rather than through line width adjustment, maintaining compact dimensions while achieving good impedance matching
Solution Approach 2:
The patent moves away from one-dimensional line width adjustment and utilizes two-dimensional geometric configurations (bending structures, spiral structures) to achieve return loss improvement. This dimensional transition enables size reduction while maintaining or improving return loss characteristics
3Reliability
If the resonant frequencies are not separated, then the antenna structure is simple, but the return loss cannot be improved satisfactorily
Solution Approach 1:
The patent controls the length from the power feeding point to the inductance shape to specifically separate the first resonant frequency (in-phase current) from the second resonant frequency (opposite-direction current). This parameter optimization achieves frequency separation and improved return loss while maintaining relatively simple antenna structure
Solution Approach 2:
The antenna utilizes electromagnetic resonance phenomena where the inductance shapes and linear portions create distinct resonant modes. By controlling the geometric parameters, the patent achieves separation of resonant frequencies, allowing independent optimization of different operating modes while maintaining structural simplicity
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 design achieves downsizing while significantly improving return loss by separating resonant frequencies and optimizing the length and position of inductance shapes, resulting in enhanced antenna performance.
Implementation Method 1
A first resonance mode, in which a current direction of current flowing through the first element is same as a current direction of current flowing through the second element, has a first resonant frequency. A second resonance mode, in which the current direction of current flowing through the first element is opposite to a current direction of current flowing through the second element, has a second resonant frequency.
Data Source
AI summary
A small antenna includes: a first element having a pair of conductors with a power feeding point; and a second element as a conductor arranged to sandwich a dielectric body. A part of the first and second elements has an inductance shape. A first resonance mode with a same current direction of the first element as the second element has a first resonant frequency. A second resonance mode with an opposite current direction of the first element to the second element has a second resonant frequency. A length from each power feeding point to the inductance shape is determined to hold the first resonant frequency within a range from a frequency slightly higher than the second resonant frequency to a high anti-resonant frequency of the second resonance mode, or a range from a frequency slightly lower than the second resonant frequency to a low anti-resonant frequency of the resonance mode.