Multi-Antenna PCB Decoupling Layer for Lower Parasitic Coupling
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Solution Overview
Problem
Existing antenna devices with multiple antennas on a circuit board suffer from parasitic couplings due to electromagnetic waves being guided along boundary surfaces, which degrade signal-to-noise ratio and transmission rates in MIMO systems, and current solutions like increasing antenna distance are limited by geometrical constraints.
Innovation Solution
Incorporating a decoupling layer with a high-impedance structure and a metal strip on a substrate layer to shift the frequency range of heightened impedance, reducing parasitic couplings by aligning the metal strip with the direction of maximum surface wave intensity and using a mushroom-like or incomplete floor electromagnetic bandgap structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple antennas are arranged on one side of a circuit board to reduce dimensions, then the device size is reduced, but parasitic couplings between antennas increase due to electromagnetic waves being guided along boundary surfaces
Solution Approach 1:
A decoupling layer is introduced as an intermediary structure between the antennas and the circuit board's boundary surfaces. This decoupling layer, configured with specific electromagnetic properties, mediates the interaction between antennas and suppresses the guidance of electromagnetic waves along the boundary surfaces, thereby reducing parasitic couplings while maintaining compact antenna arrangement
Solution Approach 2:
The electromagnetic parameters (such as permittivity, permeability, or impedance) of the decoupling layer are specifically designed and adjusted to create heightened impedance in a predetermined frequency range. This parameter change enables the decoupling layer to effectively attenuate surface waves and volume waves, reducing parasitic couplings without increasing antenna separation distance
2Object-generated harmful factors
If electromagnetic bandgap structures are used to reduce parasitic couplings, then the coupling is reduced, but the frequency range must be matched by designing individual elements, which increases design complexity
Solution Approach 1:
The decoupling layer is designed as a universal structure that can suppress parasitic couplings across multiple frequency ranges simultaneously. By configuring the decoupling layer with appropriate electromagnetic parameters, it provides heightened impedance in a predetermined frequency range without requiring separate bandgap structures for each frequency, thereby reducing design complexity while maintaining effectiveness
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 effectively reduces parasitic couplings by shifting the frequency range of heightened impedance, improving signal quality and transmission rates without altering the decoupling layer's design, specifically benefiting MIMO systems in vehicles and mobile terminals.
Implementation Method 1
The decoupling layer has a raised impedance in a predetermined frequency range. A surface component of the electromagnetic wave that runs along the circuit board device can thereby be reduced in the predetermined frequency range.
Implementation Method 2
Electromagnetic waves in this frequency range can thus be attenuated, whereby the coupling between the antennas is reduced.
Implementation Method 3
The metal strip can be dimensioned in such a way that a frequency range of a decoupling of the two antennas as a result of the decoupling layer is shifted into a lower frequency range.
Data Source
AI summary
Disclosed is an antenna device comprising at least two antennas, designed for transmitting and/or receiving electromagnetic waves, and a circuit board device, wherein the antennas are arranged on the same circuit board device, the circuit board device comprises at least one decoupling layer through which a parasitic coupling of the antennas is reduced. The circuit board device comprises at least one upper substrate layer on which at least one metal strip with predetermined dimensions is arranged, wherein the metal strip is separated from the at least one decoupling layer by at least one upper substrate layer.