Transformer-Coupled Antenna Layout for Close-Spaced Radiators
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Solution Overview
Problem
Antenna devices with closely arranged radiating elements experience reduced radiation efficiency due to electric field coupling, where currents flowing through the parasitic radiating element are weakened by electromagnetic field coupling, leading to insufficient radiation performance, especially in wide frequency range applications.
Innovation Solution
Incorporating a first and second coil coupled via an electromagnetic field, forming a transformer, and an inductor in series with the second coil to set the resonant frequency at a (2n+1)th harmonic, which enhances the current flow through the second radiating element and prevents current weakening, thereby maintaining high radiation efficiency across communication frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the first radiating element and the second radiating element are arranged close to each other to reduce antenna space, then the antenna space is decreased, but the electric field coupling between the radiating elements is strengthened, causing the currents to weaken each other and reducing radiation efficiency
Solution Approach 1:
The patent introduces an antenna coupling element as an intermediary component between the first and second radiating elements. This coupling element includes a first coil and a second coil that form a transformer, which mediates the electromagnetic coupling between the radiating elements. By using this intermediary transformer structure, the direct electric field coupling that causes current weakening is converted into controlled magnetic field coupling through the transformer, allowing close arrangement of radiating elements while maintaining radiation efficiency.
Solution Approach 2:
The patent changes the coupling mechanism from direct electric field coupling to magnetic field coupling through the transformer. By adjusting the inductance values of the coils and the coupling coefficient of the transformer, the current distribution and phase relationships are optimized to prevent current weakening. The transformer parameters are specifically designed to ensure that the current flowing through the second radiating element is enhanced rather than weakened.
2Adaptability or versatility
If an antenna coupling element implementing a transformer is used to cover a wide frequency range, then the usable frequency range is widened, but the radiation efficiency decreases when currents through the parasitic radiating element weaken due to electric field coupling
Solution Approach 1:
The transformer-based antenna coupling element serves as an intermediary that enables wide frequency range coverage while controlling current distribution. The transformer structure with specifically designed inductance values and coupling coefficients ensures that across the wide frequency range (e.g., 0.6 GHz to 2.7 GHz), the magnetic field coupling dominates over direct electric field coupling, preventing current weakening and maintaining radiation efficiency throughout the entire frequency band.
3Adaptability or versatility
If the radiating elements are arranged in parallel close proximity to support carrier aggregation, then carrier aggregation capability is enabled, but the electric field coupling strengthens and causes sufficient radiation efficiency to be unobtainable
Solution Approach 1:
The transformer-based coupling element acts as an intermediary that enables the parallel arrangement of radiating elements for carrier aggregation while controlling the coupling effects. The magnetic field coupling through the transformer coils provides the necessary interaction for multi-frequency operation and carrier aggregation, while the transformer design ensures that direct electric field coupling between the closely spaced radiating elements does not cause harmful current weakening, thus maintaining radiation efficiency.
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
The solution significantly reduces or prevents the decrease in radiation efficiency, ensuring high efficiency across a wide frequency range by aligning current flows to support enhanced communication terminal apparatus performance.
Implementation Method 1
a first coil (L1) coupled to at least one of the first radiating element and a feeding circuit, a second coil (L2) coupled to the second radiating element and coupled to the first coil via an electromagnetic field
Implementation Method 2
The first radiating element and the second radiating element are coupled to each other via an electric field
Implementation Method 3
The inductor is coupled in series with the second coil to generate the resonant frequency of the resonance circuit to be set at a frequency of a (2n+1)th harmonic
Data Source
AI summary
An antenna device includes first and second radiating elements, a first coil coupled to the first radiating element or a feeding circuit, a second coil coupled to the second radiating element and coupled to the first coil via an electromagnetic field, and an inductor. The first and second radiating elements are coupled to each other via an electric field. The harmonic resonant frequency of a resonance circuit defined by a transformer defined by the first coil and the second coil, the inductor, and the second radiating element exists within a communication frequency range. The harmonic resonant frequency is a (2n+1)th harmonic frequency, where n is an integer equal to or greater than 1.