Impedance Conversion Device for Wideband Antenna Matching
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Solution Overview
Problem
Existing antenna devices face challenges in achieving efficient impedance matching over a wide frequency band due to high insertion loss and complex circuit configurations, particularly in devices that require compatibility with multiple communication systems like GSM, DCS, UMTS, GPS, and Bluetooth.
Innovation Solution
An impedance conversion device is introduced, featuring a first inductance element connected to a feeder circuit and a second inductance element coupled with a capacitor connected to an antenna element, which reduces the frequency dependence of impedance and achieves matching by generating a transformer circuit with mutual inductance, thereby minimizing loss and strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wide-band matching circuits including multiple resonant circuits are used, then frequency band coverage is improved, but insertion loss increases and gain is insufficient
Solution Approach 1:
The impedance conversion circuit is divided into two separate circuits: a first circuit with a first inductance element connected to the feeder circuit, and a second circuit with a second inductance element connected to the antenna element. This segmentation allows each circuit to be optimized independently, reducing overall insertion loss while maintaining wide frequency band coverage through the coupling between the two inductance elements.
Solution Approach 2:
The first inductance element acts as an intermediary between the feeder circuit and the second inductance element. By introducing this intermediate element with controlled mutual inductance coupling, the circuit achieves impedance transformation across a wide frequency range without requiring multiple resonant circuits, thereby reducing insertion loss.
2Adaptability or versatility
If tunable antennas with variable capacitance elements are used, then frequency band coverage is improved, but circuit complexity increases due to switching circuits
Solution Approach 1:
The patent employs inductance elements with variable inductance values that can be dynamically adjusted to change the resonant frequency and impedance characteristics of the antenna circuit. This dynamic adjustment capability allows the antenna to cover multiple frequency bands without requiring complex switching circuits between different fixed capacitor configurations.
Solution Approach 2:
The patent changes the inductance parameter of the inductance elements to achieve frequency tuning and impedance matching across different bands. By varying the inductance value rather than switching between different capacitance configurations, the circuit maintains a simpler structure while achieving wide frequency band coverage.
3Adaptability or versatility
If switching circuits are used for frequency band switching, then adaptability is improved, but loss and strain increase reducing gain
Solution Approach 1:
The patent replaces lossy mechanical or electronic switching circuits with dynamically adjustable inductance elements that can continuously or steplessly change their inductance value. This dynamic adjustment mechanism achieves frequency band switching without the contact resistance and power loss associated with traditional switching circuits.
Solution Approach 2:
The patent substitutes mechanical switching circuits with an electromagnetic field-based inductance adjustment mechanism. By using variable inductance elements controlled through electromagnetic means rather than mechanical contacts, the system achieves frequency band switching with significantly reduced loss and strain.
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 enables effective impedance matching for both real and imaginary components of the antenna and high-frequency circuit over a wide frequency band, reducing loss and strain, and allowing for compatibility with various communication systems.
Implementation Method 1
a first circuit including a first inductance element connected to the feeder circuit and a second circuit including a second inductance element connected to the antenna element and coupled with the first inductance element
Implementation Method 2
the second circuit including a capacitor connected to the second inductance element
Data Source
AI summary
In a case in which a capacitor is not provided in parallel with a second inductance element, the impedance ratio between a first inductance element and the second inductance element is constant regardless of the frequency, but when a capacitor is provided, the parallel impedance of the capacitor and the second inductance element gradually increases at frequencies equal to and below the resonant frequency. Consequently, at frequencies equal to or below the resonant frequency, the higher the frequency becomes, the larger the value of the real portion of the impedance observed on a high-frequency-circuit side becomes. Therefore, by appropriately setting the values of the first inductance element, the second inductance element, and the capacitor, the frequency characteristics of the real portion of the impedance observed on the high-frequency-circuit side can be set to be similar to the frequency characteristics of the radiation resistance of the antenna.