Multiband Antenna with Capacitive Coupling for Shark Fin Units
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multiband antennas for vehicles are bulky and costly due to the need for multiple coaxial cables to connect multiple antennas, which increases the unit cost and complexity, especially when compact designs are required for shark fin units on car rooftops, and they are not efficient in the presence of a large grounding body like a vehicle.
Innovation Solution
A compact multiband antenna design featuring two quarter-wavelength monopole conductive plates with controlled capacitive coupling and a single feeding port, where the connecting conductor ensures in-phase current flow and reduces capacitive interference, allowing operation in the presence of a ground plane and minimizing the need for multiple coaxial connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antennas are concentrated in one shark fin unit with multiple coaxial cables, then multiple frequency bands can be covered, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple antenna functions into a single integrated structure using two conductive plates on opposite sides of a substrate. The plates are capacitively coupled and share a common ground plane, eliminating the need for multiple separate coaxial cables while covering multiple frequency bands (2.4 GHz and 5.8 GHz) through a unified design.
Solution Approach 2:
The single shark fin unit with capacitively coupled conductive plates serves multiple functions: it operates across different frequency bands (2.4 GHz and 5.8 GHz), provides omnidirectional radiation patterns, and maintains compact dimensions. This multi-functional design replaces what would traditionally require multiple separate antennas and cables.
2Volume of moving object
If the antenna size is reduced to fit within shark fin unit constraints, then the unit cost decreases, but the antenna performance may deteriorate
Solution Approach 1:
The patent transitions from a traditional planar antenna layout to a three-dimensional configuration with conductive plates on opposite sides of a substrate. This vertical stacking approach allows the antenna to maintain compact horizontal dimensions while achieving the necessary electrical length for multiple frequency bands through the capacitive coupling and quarter-wavelength monopole structures.
Solution Approach 2:
The invention changes the electrical parameters by using capacitive coupling between the two conductive plates, which allows the antenna to resonate at multiple frequencies (2.4 GHz and 5.8 GHz) simultaneously. The quarter-wavelength monopole design with specific plate dimensions and spacing enables compact size while maintaining reliable performance across both frequency bands.
3Volume of moving object
If quarter-wavelength monopole structures are used for compact size, then the antenna fits within constraints, but capacitive coupling between plates may cause interference
Solution Approach 1:
The patent converts the potentially harmful capacitive coupling between the two conductive plates into a beneficial feature. The capacitive coupling is designed to enable the antenna to operate at multiple frequencies simultaneously by creating resonant circuits at both 2.4 GHz and 5.8 GHz, rather than being treated as interference to be eliminated.
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 design achieves efficient signal transmission and reception across multiple frequency bands, including 2.5 GHz and beyond 5 GHz, while fitting within the constraints of a shark fin unit, reducing manufacturing costs and complexity by using a single feeding port and minimizing capacitive coupling, thus enhancing antenna performance and reducing the number of coaxial cables required.
Implementation Method 1
The first and second conductive plates are capacitively coupled and are electrically connected to a common ground plane
Implementation Method 2
The length of the first and second conductive plates in the longitudinal direction corresponds to quarter wavelength monopole antennas for the frequencies of signals that the plates are configured to transmit and receive
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
A multiband antenna (400) comprising a substrate (402) having a first surface and a second surface. A first conductive plate (404) is provided on the first surface of the substrate (402) and a second conductive plate (408) is provided on the second surface of the substrate (402). The second conductive plate (408) at least partially overlaps the first conductive plate (404) in the plane of the substrate. The antenna (400) also comprises a ground plane (410), wherein the substrate (402) is connected to the ground plane (410) and is substantially perpendicular to the ground plane (410), and a feeding port (412) that is electrically coupled to both the first conductive plate (404) and the second conductive plate (408). The first conductive plate (404) is configured to transmit or receive signals in a first frequency band and the second conductive plate (408) is configured to transmit or receive signals in a second frequency band.