Directional Coupler Crosstalk Cancellation MIMO Transceivers
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Solution Overview
Problem
MIMO transceivers experience crosstalk due to mutual coupling between antennas, leading to issues like back intermodulation interference and efficiency loss, which is challenging to mitigate in compact devices like mobile phones where spatial separation of antennas is not feasible.
Innovation Solution
The use of a directional coupler with carefully selected transmission line lengths and coupling factors to decouple transmitters and receivers, ensuring that crosstalk signals and coupled signals have the same magnitude but opposite phase, thereby redirecting crosstalk signals to increase signal gain at antenna ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If antennas are physically separated to reduce mutual coupling, then crosstalk is reduced, but device size increases
Solution Approach 1:
A directional coupler is introduced as an intermediary component between the antennas and transceivers. The coupler captures crosstalk signals from one antenna and redirects them to the other antenna's input, effectively canceling the harmful coupling effects without requiring physical separation of the antennas.
Solution Approach 2:
The invention converts the harmful crosstalk signals into beneficial effects by capturing them through the directional coupler and redirecting them to interfere constructively with the desired signals at the receiver input, thereby improving signal quality rather than simply eliminating the source of crosstalk.
2Object-affected harmful factors
If transmission line lengths are adjusted to control crosstalk phase, then decoupling performance improves, but device complexity increases
Solution Approach 1:
The invention adjusts specific parameters (transmission line lengths and coupler positioning) to achieve the desired phase relationship for crosstalk cancellation. By optimizing these parameters, the system achieves effective decoupling without requiring complex active control circuits or additional components.
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 approach effectively mitigates crosstalk, improves signal gain, and maintains system efficiency even in devices with closely spaced antennas, enhancing data throughput without increasing bandwidth or power requirements.
Implementation Method 1
MIMO transmitter antennas experience crosstalk due to mutual coupling between the antennas when a signal transmitted by one antenna couples to, and is therefore received by, one or more of the other transmit antennas
Implementation Method 2
The lengths of the transmission lines and the coupling factor of the directional coupler are selected to decouple the communication ports of the directional coupler
Data Source
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AI summary
A multiple antenna system is described herein that mitigates the negative effects of mutually coupled antennas on the connected transmitters and/or receivers The antenna system comprises a directional coupler and two or more antennas The directional coupler comprises multiple communication ports that each connect to corresponding antenna ports The connection ports each connect to a different transmitter, receiver, or transceiver A transmission line connects each antenna port to an antenna The lengths of the transmission lines and the coupling factor of the directional coupler are selected to decouple the communication ports of the directional coupler More particularly, the coupling factor and the transmission line lengths are selected so that antenna crosstalk signals caused by mutual coupling between the antennas and the coupled signals produced by the directional coupler have the same magnitude but opposite phase at the communication ports of the directional coupler