Folded Monopole Antenna Capacitor Impedance Band Expansion
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Solution Overview
Problem
Conventional multifrequency antenna devices face challenges in expanding their impedance band without increasing size, making it difficult to accommodate multiple radio systems with different frequency bands in compact portable electronic devices.
Innovation Solution
Incorporating a capacitor element between the folded monopole element and the feeding terminal, and adding additional antenna elements, such as a monopole element and a passive element, to create multiple resonance modes that expand the impedance band while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional multifrequency antenna device uses a folded monopole element with a stub, then it can support multiple frequency bands, but the impedance band cannot be expanded without adding more antenna elements which increases device size
Solution Approach 1:
The patent applies parameter changes by introducing a capacitor element that modifies the electrical characteristics of the folded monopole element. The capacitor changes the impedance parameters and resonance frequency of the antenna, enabling band expansion through electrical parameter adjustment rather than adding physical antenna elements. This resolves the contradiction by expanding the impedance band (improving adaptability) while maintaining the same physical antenna structure (avoiding volume increase).
2Adaptability or versatility
If additional antenna elements are added to expand the impedance band, then the resonance band can be expanded, but the size of the antenna device increases
Solution Approach 1:
The capacitor element serves as an intermediary component that couples the folded monopole element to the feeding terminal. Instead of adding more antenna elements to expand the resonance band, the capacitor mediates the electrical connection and modifies the resonance characteristics. This allows the resonance band to be expanded through the intermediary's electrical properties without increasing the physical size of the antenna device.
3Volume of moving object
If the antenna structure is simplified to reduce size, then the device becomes more compact, but the ability to cover multiple frequency bands is limited
Solution Approach 1:
The patent maintains a simplified antenna structure with a folded monopole element and stub, keeping the device compact. The frequency band coverage is expanded not by adding structural complexity but by changing the electrical parameters through the capacitor element. This resolves the contradiction by maintaining small physical size while achieving broad frequency band coverage through parameter modification.
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 solution effectively expands the resonance band of the antenna device from 720 MHz to 1,100 MHz, allowing it to cover multiple frequency bands used by LTE and 3G standard radio systems, while maintaining a compact size and improving impedance matching.
Implementation Method 1
a capacitor element (5) is inserted between the stub (411) and the feeding terminal (22)
Implementation Method 2
the first antenna element (41) has a first end (41a) connected to a feeding terminal (22), a second end (41d) connected to a first ground terminal (31), and a middle portion (41b) folded, with a stub (411) being provided between the forward portion and backward portion formed by this folding
Data Source
AI summary
According to one embodiment; an antenna device according to this embodiment includes the first antenna element formed from a folded monopole element and a capacitor element. The first antenna element has a first end connected to a feeding terminal, a second end connected to the first ground terminal, and a middle portion folded, with a stub being provided between the forward portion and backward portion formed by this folding. The capacitor element is inserted between the stub and the above feeding terminal of the forward portion of the first antenna element.