Antenna Tuning via Variable Impedance Coupling
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Solution Overview
Problem
Small antennas for mobile devices operating in the 100MHz to 5GHz frequency range face challenges in achieving sufficient radiation efficiency and receiver sensitivity due to size constraints, with existing broad band or multiple resonance designs falling short in meeting radiation specifications within a small physical volume.
Innovation Solution
The integration of a digital variable capacitor, such as a MEMS DVC, and a variable impedance device like a switched inductor and/or capacitor bank, coupled with a parasitic element to a printed circuit board, allows for tuning of the antenna resonance frequency without affecting other bands, enhancing radiation efficiency and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna size is reduced to fit small portable devices, then the device size is reduced, but the radiation efficiency and receiver sensitivity deteriorate
Solution Approach 1:
The patent employs a variable impedance device that can dynamically adjust the antenna's electrical characteristics. By changing the impedance state, the antenna can be tuned to different resonance frequencies, allowing a small physical structure to achieve optimal radiation efficiency across multiple frequency bands through dynamic reconfiguration rather than physical size changes
Solution Approach 2:
The invention changes the electrical parameters of the antenna system by introducing a variable impedance device that modifies the reactive component of the antenna circuit. This allows the antenna to maintain resonance at different frequencies while keeping the physical dimensions small, effectively decoupling the radiation efficiency from the physical size constraint
2Loss of energy
If broad band or multiple resonance antenna designs are used to improve radiation efficiency, then the radiation specifications are met, but the device complexity increases
Solution Approach 1:
The variable impedance device serves multiple functions: it acts as an impedance matching network, a frequency tuning mechanism, and a band selection switch. This single component performs what would traditionally require multiple separate antenna elements or complex matching networks, thereby reducing overall device complexity while maintaining high radiation efficiency across multiple bands
Solution Approach 2:
Instead of designing complex multi-resonance antenna structures with different geometries, the invention achieves multi-band operation by changing the electrical parameters (impedance and reactance) of a single antenna structure. This parameter-based approach is simpler than structural complexity, reducing design and manufacturing complexity
3Loss of energy
If the antenna is tuned for one frequency band, then the radiation efficiency for that band is optimized, but the performance in other bands is affected
Solution Approach 1:
The variable impedance device enables dynamic reconfiguration of the antenna's electrical characteristics, allowing the system to adapt to different frequency bands on demand. Each band can be independently optimized by switching the impedance device to the appropriate state, and the antenna can maintain versatility across multiple bands through this dynamic adaptability rather than fixed design
4Adaptability or versatility
If a variable impedance device is integrated to enable frequency tuning, then the adaptability and radiation efficiency are improved, but the device complexity increases
Solution Approach 1:
The variable impedance device is designed to perform multiple functions within a single component: frequency tuning, impedance matching, and band selection. This multi-functionality reduces the need for separate components for each function, thereby limiting the increase in device complexity while achieving improved adaptability and frequency tuning capability
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 solution maximizes antenna radiation efficiency, enabling coverage of required telecommunication bands within a small volume while allowing independent tuning of different frequency bands, thereby optimizing performance across the desired frequency spectrum.
Implementation Method 1
a digital variable capacitor connected between the parasitic element and the printed circuit board, wherein the digital variable capacitor is spaced from the grounded leg
Implementation Method 2
a parasitic element directly connected to a ground plane of the printed circuit board through a grounded leg, wherein the parasitic element is spaced from and parallel to the linear antenna conductor
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present invention generally relates to small antennas suitable for mobile devices operating in the high frequency and radio frequency bands in the range 100MHz to 5GHz. The antennas may be coupled to a DVC such as a MEMS DVC. The antenna may be coupled to a printed circuit board disposed inside of the mobile device, such as a mobile phone or smart phone.