Multi-band Antenna with Segmented Slots for Compact Vehicle Integration
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Solution Overview
Problem
Standard shark fin antennas face challenges in reducing size while maintaining frequency coverage, as smaller dimensions lead to reduced fractional bandwidth and increased return loss, making them unsuitable for multiple communication standards like GSM900, GSM1800, and 802.11p.
Innovation Solution
A multi-band antenna design featuring a planar substrate with three slots and two antenna feeds, allowing for tuning across different frequency bands, including 825-960 MHz, 1.7-4.2 GHz, and 4.95-6.0 GHz, with the third slot tuned to a high frequency, enabling compact integration in vehicle communications systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna size is reduced to fit in the shark fin housing, then the antenna can be integrated into the vehicle roof, but the fractional bandwidth and radiation resistance are reduced
Solution Approach 1:
The antenna is divided into three separate slots (first slot, second slot, third slot) that can be independently tuned to different frequency bands. This segmentation allows each slot to be optimized for specific frequency ranges while maintaining overall compact size, resolving the contradiction between small physical dimensions and adequate bandwidth coverage.
Solution Approach 2:
The patent transitions from a traditional single-dimensional monopole antenna to a two-dimensional planar substrate with multiple slots arranged in specific patterns. This dimensional change enables multi-band operation within a compact footprint by utilizing spatial distribution of electromagnetic fields across the planar surface, thereby maintaining radiation resistance and bandwidth while reducing overall antenna volume.
2Volume of moving object
If the antenna size is reduced, then the antenna fits in the housing, but the return loss increases and matching to the radio becomes non-optimal
Solution Approach 1:
Each slot is designed with specific local geometric characteristics (width, length, position) that are optimized for its intended frequency band. The first slot has dimensions optimized for lower frequencies, the second slot for intermediate frequencies, and the third slot for higher frequencies. This local optimization of geometric parameters enables each slot to achieve optimal impedance matching and low return loss at its designated frequency range despite the overall compact antenna size.
Solution Approach 2:
The patent employs systematic variation of geometric parameters (slot widths, lengths, positions, and orientations) to achieve multi-band operation with optimal matching. By changing these parameters across different slots and adjusting feed point locations, the antenna achieves low return loss across multiple frequency bands while maintaining a compact form factor that fits within the shark fin housing constraints.
3Device complexity
If a single resonant antenna element is used, then the antenna structure is simple, but it cannot support multiple frequency bands like GSM900, GSM1800, and 802.11p
Solution Approach 1:
The antenna substrate serves multiple functions simultaneously: it provides mechanical support, acts as a ground plane, and hosts three differently-tuned slots that operate across multiple frequency bands. This multi-functional design enables a single compact antenna structure to support diverse communication standards (GSM900, GSM1800, 802.11p, etc.) without requiring separate antennas for each band, thereby achieving versatility while maintaining structural simplicity.
Solution Approach 2:
The patent combines three differently-tuned resonant elements (slots) into a single integrated antenna structure on one planar substrate. By merging these elements and sharing common ground plane and substrate, the design achieves multi-band capability without proportionally increasing overall antenna volume or structural complexity, as the slots are arranged to utilize available space efficiently within the shark fin housing.
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 multi-band performance with high radiation efficiency and minimal influence between frequency bands, supporting various communication standards without the need for additional antennas, and is resistant to detuning due to nearby objects.
Implementation Method 1
A resonant quarter wave monopole antenna (L=λ/4) is a classical antenna that is used above a rooftop of a vehicle or above a ground plane. The third slot is tuned to a frequency in the highest range... wherein the second anti-resonance frequency is lower than 3 times the first anti-resonance frequency.
Data Source
AI summary
The invention provides a multi-band antenna comprising a planar substrate which in use is intended for vertical mounting, and has a bottom edge and a top edge. A conductor pattern is printed on one side of the substrate with three slots. A first slot is a U or J shape facing downwardly and a second is a U or J shape facing upwardly. A third slot extends in the vertical direction and is open at the top. A first antenna feed is coupled to a horizontal track of the second slot and a second antenna feed is coupled to the third slot. The three slots together provide multi-band performance in three bands.