Mode Balancing Parasitic Structure for Multimode Antenna Arrays
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Solution Overview
Problem
Multiple-input multiple-output (MIMO) antennas suffer from mutual coupling, which degrades signal-to-interference-noise ratio (SINR), signal processing convergence, carrier frequency offset estimation, channel estimation, angle of arrival, error rate, and capacity, as well as active voltage standing wave ratio (VSWR), particularly due to the close proximity of radiating elements in compact wireless communication products.
Innovation Solution
A parasitic structure is introduced, comprising a ground plane with active and grounded radiators, and non-conductive slots to reduce mutual coupling by balancing mode operations, including a 3×3 or 4×4 array configuration with centrally disposed parasitic structures and cross-shaped slots, enhancing port isolation and mode balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If radiating elements are placed in close proximity to satisfy compactness requirements, then the device size is reduced, but mutual coupling increases and degrades antenna performance
Solution Approach 1:
A parasitic structure consisting of a grounded radiator and non-conductive slot is introduced as an intermediary element between the active radiating elements. This parasitic structure mediates the electromagnetic interaction between closely spaced radiators, balancing the even and odd modes to reduce mutual coupling effects while allowing the radiating elements to remain in close proximity for compact antenna design
Solution Approach 2:
The invention changes the electromagnetic parameters of the antenna system by introducing a parasitic structure that modifies the current distribution and impedance characteristics. The grounded radiator and non-conductive slot alter the even and odd mode resonant frequencies and impedance values, enabling mode balancing that reduces mutual coupling in compact configurations
2Reliability
If MIMO pre-coding and decoding schemes are implemented to mitigate mutual coupling, then signal processing is improved, but the output SINR cannot be sufficiently improved and device complexity increases
Solution Approach 1:
The parasitic structure performs preliminary action by reducing mutual coupling at the physical antenna level before signals are processed electronically. By balancing the even and odd modes through the grounded radiator and non-conductive slot, the antenna system pre-mitigates coupling effects, reducing the burden on subsequent signal processing algorithms and improving output SINR more effectively than post-processing alone
3Reliability
If various diversity techniques are utilized to address mutual coupling degradation, then antenna performance is partially improved, but the techniques are of limited usefulness in controlling adverse effects
Solution Approach 1:
The invention converts the harmful mutual coupling effect into a beneficial mode-balancing mechanism. The parasitic structure with grounded radiator and non-conductive slot transforms the strong electromagnetic coupling between closely spaced radiators into controlled even and odd mode resonances, where the coupling is harnessed to create balanced modes that improve performance rather than degrade it
Data Source
AI summary
An apparatus is provided to mitigate the adverse effects of mutual coupling. The apparatus includes a ground plane and first and second active radiators spaced from the ground plane. The first and second active radiators are configured to the electrically coupled to at least one of a receiver, a transmitter or a transceiver. The antenna also includes a grounded radiator electrically coupled to the ground plane and positioned between the first and second active radiators. The ground plane defines a non-conductive slot positioned between the first and second active radiators and bounded by the ground plane.