Coil Antenna Resonance Tuning for Harmonic Wave Suppression
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Solution Overview
Problem
Conventional coil antennas in motor vehicles face challenges in suppressing harmonic waves, which interfere with other frequency bands, as they lack the space for additional electrical conductor structures like band-stop filters, unlike PCB-based antennas.
Innovation Solution
A coil antenna is arranged on a support element, such as a ferrite core or housing, to create a parasitic parallel capacitance that, combined with its self-inductance, forms a parallel resonant circuit acting as a band-stop filter, effectively damping harmonic waves by setting the natural resonant frequency to an integer multiple of the transmission frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If additional electrical conductor tracks are inserted into a PCB-based antenna structure to create a band-stop filter for suppressing harmonic waves, then the harmonic wave suppression is improved, but the space requirement for the antenna structure increases
Solution Approach 1:
The invention extracts the band-stop filter function from the PCB antenna structure and implements it using a separate coil antenna with ferrite core. This separates the filtering function from the antenna structure, allowing harmonic suppression without increasing the PCB antenna area.
Solution Approach 2:
The ferrite core acts as an intermediary element that provides both magnetic properties for antenna operation and lossy characteristics for harmonic suppression. This single component serves dual purposes: enabling the coil antenna function while simultaneously damping harmonic waves through its material properties.
2Object-generated harmful factors
If additional electrical conductor tracks are added to an antenna structure on a circuit board to prevent coupling between different parts, then the coupling prevention is improved, but the space requirement increases
Solution Approach 1:
The invention extracts the coupling prevention function from the PCB antenna design and implements it through the coil antenna structure with ferrite core. The ferrite core provides magnetic isolation that prevents coupling between different parts of the antenna structure without requiring additional conductor tracks.
3Area of stationary object
If a coil antenna is used instead of a PCB-based antenna, then the availability of surface for additional electrical conductor structures is improved, but the ability to implement band-stop filters is worsened
Solution Approach 1:
The coil antenna with ferrite core is designed to be self-sufficient, where the ferrite core itself provides the harmonic damping function without requiring separate band-stop filter circuits. The material properties of the ferrite core enable it to serve both as a magnetic support structure and as a harmonic suppressor.
Solution Approach 2:
The invention changes the approach from electrical filtering (conductor tracks) to material-based filtering (ferrite core lossy properties). By changing the parameter from electrical circuit implementation to material property utilization, the coil antenna achieves harmonic suppression without requiring additional conductor structures.
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 allows for the suppression of harmonic waves without increasing the antenna's space requirements, ensuring the radio signal emitted has reduced interference and maintains a compact design, effectively preventing harmonic interference with other radio technologies.
Implementation Method 1
a parasitic parallel capacitance is obtained in parallel with the self-inductance of the coil antenna
Implementation Method 2
the self-inductance of the coil antenna
Implementation Method 3
the parallel capacitance together with the self-inductance collectively produce a parallel resonant circuit having a predetermined natural resonant frequency
Implementation Method 4
the parallel resonant circuit...acts as a band-stop filter
Implementation Method 5
The material of the support element, that is to say, the support material, is preferably an electrical insulator, but with a known value of the dielectric constant
Data Source
AI summary
A transmission device for a motor vehicle for transmitting a radio signal is provided. A coil antenna is provided for emitting the radio signal, and an electric driver circuit is designed to generate an electric alternating current with a specified transmission frequency in the coil antenna. The coil antenna is arranged on at least one support element, and a parasitic parallel capacitance acting parallel to an intrinsic inductance of the coil antenna is produced by virtue of the geometry and/or the material of the at least one support element and/or by virtue of the shape of the coil antenna, the parasitic parallel capacitance together with the intrinsic inductance functioning as a parallel resonant circuit with a specified intrinsic resonant frequency with respect to the driver circuit.