Miniaturized Antenna with Switched Lumped Elements
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Solution Overview
Problem
Existing frequency-tunable antennas for mobile terminals and PCs face challenges in miniaturization, as they suffer from reduced bandwidth and radiative efficiency due to active elements, and often require multiple feeding points, which complicates frequency adjustment and increases loss.
Innovation Solution
The antenna apparatus incorporates a folded monopole antenna with a frequency switching circuit that includes a first lumped constant element and a switch, allowing selective connection of second lumped constant elements to adjust resonant frequency, reducing active element loss and maintaining a common feeding point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna apparatus is miniaturized, then the size is reduced, but the radiative efficiency decreases due to reduced radiative resistance
Solution Approach 1:
The patent changes the electrical parameters of the antenna by introducing lumped constant elements (inductors and capacitors) to adjust the resonant frequency and impedance characteristics. This allows the miniaturized antenna to maintain proper resonance conditions and radiative efficiency despite its reduced physical size.
Solution Approach 2:
The patent uses lumped constant elements as intermediary components between the antenna element and the feeding point. These intermediate elements (inductors L1-L4 and capacitors C1-C4) serve to transform the impedance and adjust the resonant frequency, enabling the small antenna to achieve efficient radiation.
2Adaptability or versatility
If active elements such as switches are used to adjust operating frequency, then frequency tuning capability is improved, but loss at the active element increases and radiative efficiency decreases
Solution Approach 1:
The patent replaces expensive and lossy active elements (such as switches) with passive lumped constant elements (inductors and capacitors). These passive components have negligible loss compared to active elements, thereby maintaining radiative efficiency while still providing frequency tuning capability through switching between different passive element configurations.
Solution Approach 2:
The patent substitutes the electrical/mechanical switching mechanism with a configuration that uses passive LC circuits. Instead of using active electronic switches that introduce loss, the system uses switches to reconfigure passive inductor and capacitor connections, achieving frequency tuning without the losses associated with active elements.
3Adaptability or versatility
If multiple feeding points are used to achieve frequency adjustment, then frequency flexibility is improved, but device complexity and loss increase
Solution Approach 1:
The patent makes the single feeding point universal by designing the lumped constant element network (inductors L1-L4 and capacitors C1-C4) to provide multiple resonant frequencies and impedance transformations from one feeding point. This single point can support multiple wireless communication systems and frequency bands, eliminating the need for multiple feeding points while maintaining frequency flexibility.
Solution Approach 2:
The patent merges the functions of multiple feeding points into a single feeding point by combining multiple LC resonant circuits and impedance transformation networks that are all connected to one feeding point. This consolidation reduces device complexity and the number of connection points while maintaining the ability to operate at multiple frequencies.
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 radiative efficiency and allows for frequency tuning while maintaining a compact design with a single feeding point, effectively addressing the limitations of existing miniaturized antennas.
Implementation Method 1
The antenna apparatus has a folded monopole antenna element, a frequency switching circuit, and a common feeding point. The frequency switching circuit includes a first lumped constant element, a switch, and at least one second lumped constant element. The switch is configured to select a current path in accordance with a control signal. The at least one second lumped constant element is selectively connectable in parallel to the first lumped constant element through the switch.
Implementation Method 2
the loss at the active element adversely influences the antenna radiative efficiency. This influence is more prominent as the antenna apparatus is miniaturized, reducing the radiative resistance of the antenna elements.
Data Source
AI summary
According to one embodiment, an antenna apparatus comprises an antenna element connected to a feeding point, a grounded first lumped constant element connected to the antenna element, and a grounded second and third lumped constant elements connected to the antenna element through a selector. The selector is configured to connect the grounded second lumped constant element to the antenna element in order to lower a resonant frequency of the antenna element, and to connect the grounded third lumped constant element to the antenna element in order to raise the resonant frequency of the antenna element.