Multiband Antenna with Capacitive Plates for Compact Automotive Shark Fin
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Solution Overview
Problem
Current automotive antennas are bulky and costly due to the need for multiple coaxial cables, which increases the unit cost and reduces efficiency, especially when trying to fit multiple frequency bands within a compact 'shark fin' unit on vehicles, limiting their operational efficiency and fractional bandwidth.
Innovation Solution
A compact multiband antenna design featuring a substrate with conductive plates and a feeding port that utilizes double resonance tuning through capacitive and inductive structures, allowing independent tuning of frequency bands and reducing the need for coaxial cables by integrating RF integrated circuits close to the antenna, thus minimizing physical size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple antennas are concentrated in one shark fin unit, then the number of antennas is reduced and space is saved, but the device complexity increases and manufacturing precision requirements increase
Solution Approach 1:
The antenna is divided into multiple conductive plates (first, second, third, and fourth conductive plates) with distinct functions. Each plate serves specific frequency bands or impedance tuning purposes, allowing the complex multiband antenna to be segmented into manageable functional units that can be independently optimized and manufactured.
Solution Approach 2:
Multiple frequency bands (0.5GHz to 3.5GHz) are merged into a single antenna structure by combining multiple conductive plates with different geometries and configurations. The first and second conductive plates handle lower frequency bands while the third and fourth plates handle higher frequency bands, achieving multiband operation in one integrated unit.
2Volume of moving object
If the antenna size is reduced to fit in compact units, then space is saved, but the fractional bandwidth and operational efficiency decrease
Solution Approach 1:
The antenna design transitions from traditional planar structures to a three-dimensional configuration with conductive plates positioned at different heights and orientations above the ground plane. This vertical dimensionality allows the antenna to achieve multiband operation and improved bandwidth within a compact footprint by utilizing space in the vertical direction rather than expanding horizontally.
Solution Approach 2:
Different regions of the antenna structure are optimized for different frequency bands. The first and second conductive plates are designed with specific geometries for lower frequency operation, while the third and fourth plates are configured for higher frequency bands. Each local region of the antenna has tailored electrical characteristics to maintain high efficiency at its designated frequency range.
3Reliability
If coaxial cables are used to connect antennas to electronic devices, then reliable electrical connection is achieved, but the cost increases significantly
Solution Approach 1:
The design replaces traditional coaxial cable connections with integrated microstrip transmission lines and PCB trace routing. The feeding port is directly integrated into the substrate, eliminating the need for separate coaxial cables and connectors. This substitution of mechanical connection systems with planar transmission structures reduces manufacturing complexity and cost while maintaining reliable electrical connections.
4Adaptability or versatility
If independent tuning of frequency bands is implemented, then the antenna can operate at multiple frequencies, but the device complexity increases
Solution Approach 1:
Independent tuning of frequency bands is achieved by varying geometric parameters of the conductive plates, such as their lengths, widths, positions, and spacing from the ground plane. By adjusting these physical dimensions and configurations, each frequency band can be independently optimized without requiring complex electronic tuning circuits or additional components.
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 operation across multiple frequency bands (0.5GHz to 3.5GHz) with improved fractional bandwidth and reduced size, fitting within a shark fin unit while minimizing coaxial cable requirements, thereby reducing costs and enhancing performance.
Implementation Method 1
a second conductive plate on the second surface of the substrate, the second conductive plate coupled to a signal terminal of a feeding port, and wherein the second conductive plate is aligned, possibly in a plane of the substrate, in order to provide capacitance with the first conductive region; a third conductive plate on the second surface of the substrate, wherein the third conductive plate is aligned, possibly in a plane of the substrate, in order to provide capacitance with the second conductive region
Implementation Method 2
the first conductive region is couplable to ground by a shorting element
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A multiband antenna (1200, 1300) comprising a substrate (1203, 1303) having a first surface (1204) and a second surface (1307). A first conductive plate (1210) is located on the first surface (1204) of the substrate (1203), the first conductive plate comprising a first conductive region (1201), which is couplable to ground by a shorting element (1206), and a second conductive region (1202). The first conductive region (1201) and second conductive region (1202) are located so as to define a gap (1205) therebetween. The antenna also has a second conductive plate (1308) on the second surface (1308) of the substrate (1303). The second conductive plate (1308) is coupled to a signal terminal (1314a) of a feeding port (1314) and positioned in order to provide capacitance with the first conductive region (1201). The antenna also has a third conductive plate (1309) on the second surface (1307) of the substrate (1303). The third conductive plate (1309) is positioned in order to provide capacitance with the second conductive region (1202), and a connecting conductor (1512, 1612) configured to electrically couple the third conductive plate (1309) to the second conductive region (1202).