Interlayer-Coupled Inductance Elements for Multiband Impedance Matching
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Solution Overview
Problem
Multiband support antenna apparatuses face challenges in achieving impedance matching across wide frequency bands due to varying input impedance of antenna elements, which is difficult to address with traditional transformer-based impedance transformation circuits that require constant transformer ratios, leading to frequency dependence and limited coupling coefficients with small inductance coils.
Innovation Solution
A method of designing an impedance transformation circuit using interlayer-coupled inductance elements with loop conductors, where the second inductance element is formed with at least two layers of loop conductors sandwiching the first inductance element, allowing for adjustable inductance values and coupling coefficients to achieve a predetermined impedance transformation ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transformer circuit with constant transformer ratio is used for impedance matching, then impedance matching can be achieved in one frequency band, but matching is lost in other frequency bands
Solution Approach 1:
The patent applies dynamics by making the transformer ratio variable across frequency bands. The transformer circuit is designed with different inductance values (L1, L2, L3) that create different effective transformer ratios at different frequencies. At low band frequency, the transformer ratio is approximately L1/L2, while at high band frequency, it becomes approximately (L1+L3)/L2, enabling impedance matching in multiple frequency bands
Solution Approach 2:
The patent changes the electrical parameters of the transformer circuit by introducing multiple inductance elements with different values. The inductances L1, L2, and L3 are specifically designed to provide appropriate transformer ratios for different frequency bands, allowing the circuit to adapt its transformation ratio based on the operating frequency
2Volume of moving object
If small inductance values are used in transformer coils, then the antenna apparatus can be miniaturized, but the coupling coefficient becomes insufficient and frequency dependence increases
Solution Approach 1:
The patent applies local quality by creating regions of strong magnetic coupling between specifically positioned coils. The low band coil and high band coil are arranged to overlap in plan view, creating a localized region of strong mutual coupling. This local optimization of coupling quality compensates for the small overall size of the apparatus
Solution Approach 2:
The patent uses nesting by placing the high band coil within the spatial envelope of the low band coil's magnetic field. The coils are positioned such that they overlap in plan view and are separated in the stacking direction, creating a nested configuration that maximizes coupling while minimizing overall volume
3Reliability
If the primary coil and secondary coil have the same shape to achieve desired coupling coefficient, then sufficient coupling is obtained, but it becomes very difficult to obtain different inductances for primary and secondary coils
Solution Approach 1:
The patent resolves the contradiction by moving from a two-dimensional planar arrangement to a three-dimensional stacked configuration. The low band coil and high band coil are positioned on different layers separated in the stacking direction, yet overlap in plan view. This dimensional arrangement allows both strong coupling (through planar overlap) and different inductances (through different numbers of turns and dimensional configurations)
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 design achieves a high coupling coefficient and impedance transformation ratio despite small coil sizes, ensuring effective impedance matching across both LowBand and HighBand frequencies, reducing frequency dependence and enabling efficient operation of multiband antenna apparatuses.
Implementation Method 1
an impedance transformation circuit including a transformer circuit (L1, L2) connected between a first high-frequency circuit (30) and a second high-frequency circuit (11)
Implementation Method 2
the first inductance element and the second inductance element are interlayer-coupled to each other, and the loop conductors are disposed to sandwich the first inductance element in the stacking direction
Data Source
AI summary
To design an impedance transformation circuit, a transformer ratio of a transformer circuit is determined according to an impedance ratio. A coupling coefficient between a first inductance element and a second inductance element, an inductance of the first inductance element, and an inductance of the second inductance element are determined. A shape of the second inductance element is determined. A shape of the first inductance element is determined such that the first inductance element includes at least two layers of loop conductors, and an interlayer distance between the loop conductors is determined such that an inductance value of the first inductance element is a desired value.