Multiband Antenna Switching Electrical Length for Impedance Matching
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Solution Overview
Problem
Existing antennas, such as multi-resonant and reactance-loaded antennas, face challenges in significantly changing resonant frequencies without causing input impedance mismatch, making them unsuitable for applications like WLANs that require broad frequency coverage.
Innovation Solution
The proposed antenna device consists of a first unbalanced-fed antenna element and a second monopole antenna element with a common feeding point, where the second element can switch between ungrounded and grounded states, allowing for a significant change in resonant frequency while minimizing input impedance mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a reactance element is used to achieve multi-resonance, then the antenna can resonate at multiple frequencies, but the resonant frequency cannot be significantly changed without adjusting the reactance value
Solution Approach 1:
The patent applies the dynamics principle by making the antenna element length adjustable. The second antenna element can be extended or retracted to change its electrical length, thereby significantly changing the resonant frequency without requiring reactance value adjustments. This dynamic length modification allows the antenna to adapt to different frequency requirements while maintaining simple reactance element configuration.
Solution Approach 2:
The patent applies parameter changes by modifying the physical length parameter of the antenna element rather than changing the reactance value. By extending or retracting the second antenna element, the resonant frequency is significantly changed through geometric parameter modification, which is simpler and more direct than adjusting reactance values to achieve the same frequency tuning effect.
2Volume of moving object
If the T-type monopole antenna operates in parallel resonance mode to achieve downsizing, then the input impedance increases, but this causes mismatch with feeders designed for series resonant frequency matching
Solution Approach 1:
The patent applies segmentation by dividing the antenna into multiple independent elements (first antenna element and second antenna element) with different functions. The first element provides the main radiating structure while the second element acts as a可调 length extension. This segmentation allows the antenna to achieve downsizing through parallel resonance mode while the adjustable second element can compensate for impedance mismatch by modifying the overall electrical length and input impedance characteristics.
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 enables the antenna device to broaden its frequency characteristic, effectively covering multiple bands with reduced VSWR mismatch, thus addressing the limitations of existing antennas in multiband operations.
Implementation Method 1
a resonant frequency of which a length of the antenna element corresponds to a quarter wavelength
Implementation Method 2
the switch element changes a resonant frequency of the antenna by modifying an electrical length of the antenna element
Data Source
AI summary
An antenna device and a radio apparatus are provided. The antenna device is configured to be coupled to a feeding point of the radio apparatus. The antenna device has a first antenna element and a second antenna element. The first antenna element is configured to be an unbalanced-fed antenna fed at the feeding point to resonate at a first frequency. The second antenna element is configured to be a monopole antenna having an open end and to be fed at the feeding point. The first antenna element and the second antenna element have a common portion from the feeding point to a branching point. The second antenna element is configured to be ungrounded in a first state to resonate at a second frequency lower than the first frequency and to be grounded in a second state at a switch point between the branching point and the open end.