Orthogonal PCB Antenna Layout With Decoupling for High Isolation
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Solution Overview
Problem
Existing antenna systems in electronic devices face poor isolation between multiple antennas, particularly at low-band frequencies, which affects Multiple-Input and Multiple-Output (MIMO) system performance and efficiency, leading to potential certification failures due to intermodulation and out-of-band spurious emission.
Innovation Solution
A multiband high-isolation antenna system is implemented using a generally-circular printed circuit board with two orthogonal antennas and a decoupling structure, providing high isolation and enabling five unique resonant modes, including a T-element with a center post and coplanar arms to reduce current coupling between antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple antennas are implemented in an electronic device for wireless communication, then wireless communication capability is improved, but isolation between antennas deteriorates
Solution Approach 1:
A decoupling structure is introduced as an intermediary element between the first and second antennas. This decoupling structure includes a first decoupling element connected to the first antenna and a second decoupling element connected to the second antenna, which interact to reduce mutual coupling and improve isolation between the antennas while maintaining wireless communication capability.
2Volume of moving object
If antennas are placed closer together to reduce device size, then device compactness is improved, but antenna isolation deteriorates
Solution Approach 1:
The decoupling structure serves as a mediator that enables close placement of antennas by actively managing the electromagnetic interaction between them. The decoupling elements are positioned in the space between the antennas and use electromagnetic coupling to cancel out the harmful mutual coupling, allowing compact antenna placement while maintaining isolation.
Solution Approach 2:
The decoupling structure changes the electromagnetic parameters (impedance, coupling coefficient) in the region between the antennas. By adjusting the geometry and positioning of the decoupling elements, the electromagnetic field distribution is modified to reduce mutual coupling, enabling compact antenna design with maintained isolation.
3Loss of energy
If antenna elements are increased to improve radiation performance, then radiation efficiency is improved, but device complexity increases
Solution Approach 1:
The decoupling structure performs multiple functions simultaneously: it provides decoupling between antennas, acts as additional radiation elements, and contributes to impedance matching. This multi-functionality improves radiation efficiency without proportionally increasing system complexity, as the same structural elements serve multiple purposes in the antenna system.
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 solution achieves high isolation (greater than 20 dB) between antennas across multiple bands, enhancing MIMO and diversity performance while allowing for wideband and ultra-wideband operations, reducing intermodulation and improving antenna efficiency.
Implementation Method 1
a decoupling structure connected to the printed circuit board at a location between the first antenna and the second antenna
Implementation Method 2
enabling five unique resonant modes of operation for the multimode high-isolation antenna system
Data Source
AI summary
This document describes a multimode high-isolation antenna system and associated methods and systems. The described antenna system is implemented on a generally-circular printed circuit board and can be used for wideband and ultra-wideband applications. The multimode high-isolation antenna system includes two orthogonal antennas separated by a decoupling structure. This arrangement provides high isolation between the antennas and enables five unique resonant modes of operation for the multimode high-isolation antenna system.