Asymmetrical Feed Antenna Layout for Broadband MIMO Isolation
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Solution Overview
Problem
The challenge of designing antennas for mobile devices with wide frequency band coverage, high efficiency, and miniaturization is exacerbated by the coexistence of 3G, 4G, and 5G frequency bands, increased camera volumes, and complex antenna designs, leading to mutual coupling and reduced performance in MIMO systems.
Innovation Solution
The proposed antenna design includes a radiator pair with asymmetrically fed transmission lines of unequal lengths and a feeding unit to generate multiple resonances, allowing for high isolation and broadband operation, utilizing materials like microstrip and coaxial lines, and incorporating capacitors and inductors for impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of antennas is increased to support multiple frequency bands (3G, 4G, 5G), then frequency band coverage is improved, but device complexity and mutual coupling increase
Solution Approach 1:
The patent implements a multi-band antenna that can operate across 3G, 4G, and 5G frequency bands simultaneously. The antenna structure incorporates multiple resonant elements and impedance matching networks that enable it to support multiple communication standards (WCDMA, LTE, NR) through a single antenna element, thereby reducing the total number of antennas needed while maintaining broad frequency coverage
Solution Approach 2:
The patent employs a nested structure where multiple antenna elements are integrated within a compact space. The antenna design includes nested resonant cavities and layered PCB structures that allow smaller antenna elements to be positioned within or adjacent to larger ones, enabling multi-band operation from a single antenna footprint and reducing overall device complexity
2Volume of moving object
If antenna space is compressed to achieve lightness and thinness, then device portability is improved, but antenna performance and isolation deteriorate
Solution Approach 1:
The patent transitions from planar antenna designs to three-dimensional structures by incorporating vertical stacking of antenna elements on multiple PCB layers. This dimensional transition allows the antenna to achieve the necessary electrical length and radiation efficiency in a reduced horizontal footprint, maintaining performance while compressing the antenna's occupied space
Solution Approach 2:
The patent utilizes thin-film substrate integrated waveguide (SIW) structures and flexible printed circuit board (PCB) technologies to create compact antenna elements. These thin-film implementations allow the antenna to maintain its resonant characteristics and isolation performance while being significantly thinner than traditional rigid antenna structures
3Length of moving object
If distances between antenna elements are reduced for miniaturization, then device size is improved, but mutual coupling between antennas increases
Solution Approach 1:
The patent introduces ground planes, isolation walls, and decoupling structures as intermediary elements between adjacent antenna elements. These intermediaries act as electromagnetic barriers that block coupling paths between antennas, allowing them to be positioned closer together while maintaining low mutual coupling through the insertion of these protective structures
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
This design achieves improved isolation and broadband performance, enhancing the flexibility and efficiency of antenna arrangements in electronic devices, supporting multiple frequency bands and reducing the occupied space.
Implementation Method 1
the transmission line is configured to generate a resonance in an adjacent frequency band of the first resonance
Implementation Method 2
the first radiator is configured to generate a first resonance
Data Source
AI summary
An antenna includes a first radiator and a transmission line having a first end and a second end. The first end is coupled proximate to a ground end or an open end of the first radiator, and a length T of the transmission line is set to satisfy T=¼λ or T=½λ, where λ is a dielectric wavelength corresponding to one of resonances generated by the antenna when the antenna is fed. A feeding circuit is coupled to a coupling point of the transmission line in a configuration for feeding the first radiator through the transmission line.