Magnetically Coupled Antenna Layout for Wideband Radiation Efficiency
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Solution Overview
Problem
Existing antenna devices struggle to achieve sufficient radiation efficiency in multiple frequency bands, particularly in low and high-frequency bands due to reduced antenna length and resonance issues.
Innovation Solution
The antenna device includes a first antenna with a feed circuit and a first radiating element, and a second antenna with a second radiating element magnetically coupled to a first coil, where the impedance of the first antenna is set higher than 50Ω at the resonant frequency of the second antenna's fundamental, allowing it to resonate at a harmonic frequency to increase the length of the second radiating element and improve radiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the antenna length is reduced to operate in high-frequency bands (3.3 GHz to 5.0 GHz), then the device size is reduced, but sufficient radiation efficiency is not achieved
Solution Approach 1:
A first antenna is introduced as an intermediary element that is magnetically coupled to the second antenna. The first antenna acts as a mediator to enhance the radiation efficiency of the second antenna by providing an additional radiating structure that is fed through a coil, thereby improving overall radiation performance without increasing the physical length of the second antenna element.
Solution Approach 2:
The impedance of the first antenna is specifically designed to be higher than about 50Ω at the resonant frequency of the fundamental of the second antenna. This parameter change in impedance creates a detuned condition that prevents the first antenna from resonating at the same frequency as the second antenna, thereby avoiding destructive interference and improving radiation efficiency in the high-frequency band.
2Adaptability or versatility
If two antennas are coupled to broaden bandwidth, then frequency band coverage is improved, but resonance interference occurs when both antennas resonate at the same frequency
Solution Approach 1:
The impedance of the first antenna is designed to be higher than about 50Ω at the resonant frequency of the fundamental of the second antenna. This parameter change ensures that the first antenna does not resonate at the same frequency as the second antenna, thereby preventing resonance interference and maintaining reliable operation across the broadened frequency band.
3Loss of energy
If the antenna length is increased to achieve sufficient radiation efficiency, then radiation efficiency is improved, but the device size increases
Solution Approach 1:
The first antenna serves as an intermediary radiating structure that compensates for the insufficient radiation efficiency of the shortened second antenna. By introducing this additional fed antenna element with magnetic coupling, the system achieves sufficient radiation efficiency without requiring the second antenna to be physically longer.
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 broadens the bandwidth and enhances radiation efficiency by preventing resonance at the fundamental frequency of the second antenna, enabling stable communication across a wide frequency range.
Implementation Method 1
The second antenna includes a second coil magnetically coupled to the first coil, and a second radiating element connected to the second coil
Data Source
AI summary
An antenna device includes first and second antennas. The first antenna includes a first radiating element connected to a feed circuit to supply a radio-frequency signal, and a first coil connected between the first radiating element and the feed circuit. The second antenna includes a second coil magnetically coupled to the first coil, and a second radiating element connected to the second coil. An impedance of the first antenna is higher than about 50Ω at a resonant frequency of a fundamental of the second antenna.