Planar Multi-Band Antenna with Bended Feed Element
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Solution Overview
Problem
Conventional Planar Inverted-F (PIFA) antennas face challenges in achieving dual broadband or broadband capabilities, particularly in compact designs, as higher frequency modes are difficult to excite, limiting their ability to operate effectively across multiple frequency bands.
Innovation Solution
A planar multi-band antenna design featuring a substrate with a metal pattern comprising multiple interconnected wires, where the fourth metal wire forms bends and impedance matching portions, allowing for multiple operating bands by activating different segments in λ/4 and λ/2 modes, and adjusting the reflection coefficient to enhance bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional PIFA architecture is used, then single-band operation is achieved, but dual broadband or broadband capability cannot be achieved
Solution Approach 1:
The antenna structure is divided into multiple distinct segments including a first radiating element, second radiating element, third radiating element, and feed element. Each segment can be independently designed to resonate at different frequency bands, enabling multi-band operation while maintaining a relatively simple overall planar structure that avoids the complexity of multiple separate antennas.
Solution Approach 2:
The planar antenna structure is designed to serve multiple frequency bands simultaneously through its multi-element configuration. The same antenna structure supports WLAN (2.4 GHz and 5 GHz bands), WiMAX (3.5 GHz band), and UWB (3.1-10.6 GHz band) operations, making it a universal solution for diverse wireless communication standards without requiring separate antennas for each band.
2Adaptability or versatility
If antenna length is increased for broadband operation, then frequency coverage improves, but antenna size increases
Solution Approach 1:
The antenna transitions from traditional three-dimensional PIFA structures to a two-dimensional planar configuration. This dimensional change allows the antenna to achieve broadband coverage through the spatial arrangement and electrical length of planar elements rather than relying on increased physical length in three dimensions, thereby maintaining compact size while expanding frequency coverage.
Solution Approach 2:
The feed element incorporates multiple bends and curved paths instead of straight-line configurations. These curved geometries increase the electrical length of the feed element, enabling it to resonate at lower frequencies and extend the overall bandwidth of the antenna system without proportionally increasing the physical footprint or bounding box dimensions of the antenna.
3Adaptability or versatility
If higher frequency modes are excited, then multi-band operation is achieved, but excitation difficulty increases
Solution Approach 1:
The third radiating element serves as an intermediary coupling structure that facilitates energy transfer between the feed element and the higher-order resonant modes of the first and second radiating elements. This intermediary element makes it easier to excite higher frequency modes by providing a gradual transition and coupling path, rather than requiring direct excitation which would be difficult to achieve.
4Area of moving object
If antenna size is reduced for compact design, then product competitiveness improves, but broadband capability deteriorates
Solution Approach 1:
The antenna employs a planar thin-film structure where all radiating elements and feed networks are fabricated on the same planar substrate layer. This thin-film approach enables compact integration while maintaining the electrical characteristics needed for broadband operation, as the planar geometry allows for optimized current distribution and impedance matching without requiring thick three-dimensional structures.
Data Source
AI summary
A planar multi-band antenna includes a substrate and a metal pattern. The metal pattern includes a first metal wire, a second metal wire, a third metal wire and a fourth metal wire. The second metal wire is disposed opposite to the first metal wire and has a grounding point. Two ends of the third metal wire are connected to the first metal wire and second metal wire, respectively, and the first metal wire is divided into a first radiation portion and a second radiation portion. The fourth metal wire is partially located between the second radiation portion and the second metal wire and forms multiple bends, and has a first impedance matching portion and a feed point, and part of the fourth metal wire coincides with the second radiation portion in a projection direction. By the activation of the feeding point and the grounding point associates with the impedance matching portion, the antenna has plural bands.