Vehicle MIMO Antenna Compact Design Isolation
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Solution Overview
Problem
Existing vehicle antenna systems are bulky and require multiple antennas to cover various radio-communication services, which affects their aesthetic and aerodynamic design, and reducing their size compromises LTE communication performance due to decreased isolation between antennas.
Innovation Solution
A compact MIMO antenna system with monopole antennas on a dielectric substrate, featuring elongated conductors with specific height-to-thickness ratios and electromagnetic coupling, allowing for reduced length without compromising isolation or LTE frequency coverage, and integrating additional communication services like a camera without shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the antenna module length is reduced to meet customer tastes and aerodynamic requirements, then the streamlined appearance is improved, but the isolation between LTE antennas deteriorates
Solution Approach 1:
The patent transitions from traditional horizontal antenna arrangement to a vertical configuration where monopole antennas extend perpendicular to the dielectric substrate. This dimensional change allows antennas to be closely spaced horizontally (meeting aesthetic requirements) while maintaining vertical isolation through the substrate, thus preserving electromagnetic isolation despite reduced overall module length.
Solution Approach 2:
The patent optimizes the height-to-thickness ratio of the first conductor within 5 to 45 to achieve resonance at first LTE frequency bands. By carefully controlling geometric parameters of the conductors and the dielectric substrate, the antenna maintains proper electromagnetic characteristics and isolation while achieving a compact form factor that meets aesthetic requirements.
2Device complexity
If multiple antennas are integrated in a single module to reduce the number of antennas, then the device complexity is reduced, but the isolation between antennas deteriorates
Solution Approach 1:
The patent combines multiple LTE antennas and other communication antennas into a single integrated module mounted on the vehicle roof. This consolidation reduces the total number of separate antenna components while maintaining proper isolation through careful design of the dielectric substrate and conductor arrangement, thus simplifying the overall system.
Solution Approach 2:
The dielectric substrate acts as an intermediary element between the monopole antennas and ground plane, providing electromagnetic isolation while allowing the antennas to be closely integrated in a single module. The substrate's dielectric properties enable the antennas to coexist in close proximity without excessive coupling.
3Reliability
If the conductor height is increased to provide resonant frequency at LTE bands, then the frequency coverage is improved, but the antenna length increases
Solution Approach 1:
The patent achieves resonance at LTE frequency bands by optimizing the height-to-thickness ratio of conductors within a specific range (5 to 45) rather than simply increasing height. This parameter optimization allows the antenna to achieve proper resonant frequency characteristics while maintaining a compact overall length that meets aesthetic and aerodynamic requirements.
Solution Approach 2:
Instead of extending antenna length horizontally, the patent utilizes vertical dimension by having monopole conductors extend perpendicular to the dielectric substrate. This allows frequency coverage requirements to be met through vertical conductor height while the horizontal footprint remains compact, satisfying both frequency coverage and length constraints.
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 achieves a 10% reduction in antenna length while maintaining isolation above 10 dB, ensuring optimal MIMO functionality across all 4G frequency bands and integrating multiple communication services in a single, compact module, enhancing both aesthetic and aerodynamic performance.
Implementation Method 1
the third conductor is electromagnetically coupled to the first and second conductors to thereby provide additional resonant frequencies at third and fourth LTE frequency bands
Implementation Method 2
The first conductor has a height and a thickness such that the height to thickness ratio is comprised within 5 to 45 so as to provide a resonant frequency at a first LTE frequency band
Data Source
AI summary
A MIMO antenna system for a vehicle comprising first and second monopole antennas, which comprises first, second and third conductors. First and second conductors are electrically connected in parallel, and the third conductor is coupled to the first and second conductors. The first conductor has a height (H1) and thickness (t1) such that the H1/t1 ratio is within 5 to 45 to provide a resonant frequency at a first LTE frequency band. The second conductor has a height of 30%-60% H1 to provide a resonant frequency at a second LTE frequency band. The third conductor provides resonant frequencies at third and fourth LTE frequency bands, and having an electrical length such that the coupling level of the third conductor with respect to first and second conductors in the third and fourth LTE frequency bands is greater than 10 dB.