MIMO Wi-Fi Antenna Layout for High Isolation and Uniform Coverage
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Solution Overview
Problem
Conventional dual-band Wi-Fi antennas are inadequate for IEEE 802.11ax applications due to poor system throughput, radio coverage, and high parasitic electromagnetic coupling, necessitating improved antenna designs with reduced parasitic coupling and enhanced efficiency.
Innovation Solution
A MIMO antenna system with vertically and horizontally polarized antennas, utilizing cable channels in the ground plane to house feeding cables, and incorporating parasitic elements to enhance isolation and uniformity, achieving tri-band capability and high antenna isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dual-band Wi-Fi antennas are used, then basic Wi-Fi functionality is provided, but system throughput, radio coverage, and return loss are relatively poor
Solution Approach 1:
The antenna system is divided into multiple independent antenna elements (at least four antennas) with different polarizations (vertical and horizontal), each handling specific frequency bands or spatial streams. This segmentation allows optimized performance for each element while achieving overall system throughput improvement and reduced return loss through independent impedance matching and radiation characteristics.
Solution Approach 2:
Different antenna elements are designed with specific local characteristics - vertically polarized antennas for certain frequency bands or spatial directions, horizontally polarized for others. Each antenna element is optimized for its specific function, creating local quality improvements that collectively enhance system throughput and return loss performance across the entire MIMO system.
2Reliability
If conventional Wi-Fi antennas are used, then basic connectivity is achieved, but parasitic electromagnetic coupling between antenna pairs is high
Solution Approach 1:
The harmful parasitic electromagnetic coupling is extracted and eliminated by using orthogonal polarizations (vertical and horizontal) for different antenna pairs. The perpendicular orientation of polarization vectors naturally isolates the electromagnetic fields, removing the harmful coupling effect between adjacent antenna elements without requiring additional shielding or filtering components.
Solution Approach 2:
The antenna system employs asymmetric polarization orientations - vertical polarization for one set of antenna pairs and horizontal polarization for another set. This asymmetry in electromagnetic field orientation creates natural isolation between antenna pairs, reducing parasitic coupling to below -20 dB and achieving cross-pair isolation greater than 43 dB between differently polarized pairs.
3Reliability
If MIMO antenna pairs with different polarizations are used, then antenna isolation is improved, but system complexity increases
Solution Approach 1:
The antenna system uses universally applicable dipole or monopole antenna structures that can be easily manufactured and deployed. These standard antenna types are configured with different polarizations to achieve multiple functions - spatial diversity, frequency band separation, and interference reduction - without requiring complex specialized antenna designs, thus maintaining manufacturing simplicity while achieving >43 dB cross-pair isolation.
4Ease of manufacture
If feeding cables are routed externally, then installation is simpler, but parasitic radiation and cross-talk between antennas increase
Solution Approach 1:
The feeding cables are nested within the conductive ground plane structure, with cable channels formed inside the ground plane to guide and shield the cables. This nesting approach allows cables to be routed through protected pathways within the existing ground plane, providing electromagnetic shielding that reduces parasitic radiation and cross-talk while maintaining relatively simple installation procedures.
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 system achieves >43 dB cross-pair isolation, reduced gain ripple, and uniform radiation without blind spots, supporting IEEE 802.11ax with improved performance and efficiency.
Implementation Method 1
The application of cable channels (grooves) in the ground plane allow the feeding cables to be accommodated at least partially within the ground plane. During operation, feeding cables will typically cause undesired parasitic radiation, which could lead to undesired cross-talk between antennas... By housing the feeding cables at least partially within the conductive ground plane, this undesired side effect could be reduced significantly
Implementation Method 2
The antenna system performance is further improved by applying a combination of differently polarized (horizontally and vertically polarized) antennas for enabling best isolation between separate MIMO pairs. The high-performance MIMO antenna system allows an architecture with tri-band capability and >43 dB cross-pair isolation
Data Source
AI summary
The invention relates to a MIMO antenna system for IEEE 802.11 WiFi communication. The invention also relates to a wireless device, such as a wireless access point (AP), a router, a gateway, and/or a bridge, comprising at least one antenna system according to the invention. The invention further relates to a wireless communication system, comprising a plurality of antenna systems according to the invention, and, preferably, a plurality of wireless devices according to the invention.