Leaky-Wave Antenna for Vehicle Glass MIMO Integration
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Solution Overview
Problem
Modern vehicles face design challenges due to the need for multiple-input multiple-output (MIMO) LTE antennas, which require increased antenna structure size when mounted on the roof, and existing glass-integrated antennas suffer from signal loss due to curvature-induced radiation patterns directed upward rather than parallel to the ground.
Innovation Solution
A thin film, flexible leaky-wave co-planar waveguide antenna with transparent conductors is mounted on vehicle glass, featuring a ground plane with opposing lines and radiating elements with leaky-wave tuning stubs to optimize radiation patterns for parallel ground directionality, suitable for MIMO LTE systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MIMO LTE antennas are mounted on the roof of the vehicle, then signal reception capability is improved, but the antenna structure size increases and interferes with vehicle design
Solution Approach 1:
The patent transitions antenna mounting from the traditional roof (horizontal plane) to the vehicle glass surface (vertical plane), utilizing the vertical dimension of the windshield. This dimensional change allows MIMO antennas to be positioned closer together while maintaining signal quality, thereby reducing the overall antenna structure volume and eliminating interference with vehicle roof design.
Solution Approach 2:
The patent employs thin film flexible substrate materials for mounting the antennas on the curved glass surface. This allows the antenna structure to conform to the glass curvature without requiring bulky housing structures, thereby reducing antenna volume while maintaining reception capability.
2Ease of manufacture
If antennas are adhered to curved vehicle windshield, then integration into vehicle glass is achieved, but radiation pattern is directed upward causing signal loss
Solution Approach 1:
The patent introduces leaky-wave tuning stubs at specific locations along the antenna radiating element to locally modify the radiation characteristics. These stubs create controlled impedance discontinuities that extract energy from the traveling wave and redirect it horizontally, compensating for the upward tilt caused by glass curvature and reducing signal loss.
Solution Approach 2:
The patent modifies the electrical parameters of the antenna by adding tuning stubs with specific lengths and positions, which change the phase and amplitude distribution along the radiating element. This parameter adjustment transforms the radiation pattern from upward-directed to horizontally-directed, overcoming the signal loss issue while maintaining glass integration.
3Volume of moving object
If MIMO antennas are placed close together, then antenna structure size is reduced, but signal de-correlation between antenna ports becomes difficult to achieve
Solution Approach 1:
The patent positions MIMO antennas in the vertical dimension on the glass surface rather than horizontally on the roof. This vertical arrangement allows closer spacing while maintaining sufficient signal de-correlation through the use of leaky-wave tuning stubs that create distinct radiation patterns for each antenna element.
Solution Approach 2:
The patent replaces the mechanical spacing requirement (physical distance between antennas) with an electromagnetic solution (leaky-wave tuning stubs) to achieve signal de-correlation. The stubs create phase and amplitude differences that de-correlate the signals electrically, allowing antennas to be placed closer together without sacrificing MIMO performance.
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 allows for efficient signal reception and transmission by directing antenna radiation parallel to the ground, reducing signal loss and enabling better integration of MIMO LTE antennas on vehicle glass without increasing the antenna structure size, thus addressing design and functionality challenges.
Implementation Method 1
A series of crossing bus bars are provided along the radiating element at predetermined intervals within the gap. The bus bars extract energy from a wave traveling along the radiating element and cause the radiation pattern of the antenna to be directed parallel to the ground.
Implementation Method 2
The bus bars extract energy from a wave traveling along the radiating element and cause the radiation pattern of the antenna to be directed parallel to the ground. In one embodiment, the distance between adjacent the bus bars is much less than the free space wavelength of the center of the frequency band of interest so as to create circular currents in the bus bars that generate radiation.
Data Source
AI summary
A thin film, flexible, leaky-wave CPW antenna that can mounted to a dielectric substrate on a vehicle, such as vehicle glass, where the antenna has application for a MIMO LTE cellular system, and where the conductive portion of the antenna can employ transparent conductors. The antenna includes a ground plane having opposing first and second ground lines defining a gap therebetween and an antenna radiating element extending between the ground lines in the gap. The antenna radiating element includes a plurality of leaky-wave tuning stubs crossing the antenna radiating element at predetermined intervals that operates to change the radiation pattern of the antenna to be more parallel to the ground.