Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion

This paper presents a novel self-isolation technique for multiple-input multiple-output (MIMO) microstrip patch antenna (MPA) arrays using annular via-based mode conversion. The proposed approach transforms the TM20 mode into a hybrid TM20+TM01 mode, enabling high isolation in both E-plane and H-pla...

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Main Authors: Manzoor Elahi, Slawomir Koziel, Leifur Leifsson
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/11045917/
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author Manzoor Elahi
Slawomir Koziel
Leifur Leifsson
author_facet Manzoor Elahi
Slawomir Koziel
Leifur Leifsson
author_sort Manzoor Elahi
collection DOAJ
description This paper presents a novel self-isolation technique for multiple-input multiple-output (MIMO) microstrip patch antenna (MPA) arrays using annular via-based mode conversion. The proposed approach transforms the TM20 mode into a hybrid TM20+TM01 mode, enabling high isolation in both E-plane and H-plane coupled configurations without requiring additional decoupling structures. A compact <inline-formula> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> single-fed antenna array is designed using annular vias and an open slot in the MPA, serving as a fundamental unit for the MIMO array. By exciting an element with a hybrid mode in the H-plane coupled MIMO array, a TM10 mode of very low intensity is induced on the adjacent half and a TM01 mode on the rear half of the nearby patch that leads to high isolation. However, in the E-plane coupled MIMO array a quasi-TM01 mode is induced on each half of the nearby patch whose overall field distribution resembles a TM11 mode due to the slot in the patch and the annular vias. Thus, in both configurations, the coupled modes are either orthogonal or exhibit weak field distribution concerning the excited mode. To validate the technique, <inline-formula> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> MIMO arrays were fabricated and measured. An isolation levels of 38 dB and 40 dB is demonstrated in the E-plane and H-plane configurations, respectively, at 5.8 GHz. The measured cross-polarization level is &#x2212;50 dB in the broadside direction for the E-plane coupled array in both planes and it is 18 dB/23 dB at <inline-formula> <tex-math notation="LaTeX">$\phi =0^{\circ } $ </tex-math></inline-formula>/<inline-formula> <tex-math notation="LaTeX">$\phi =90^{\circ } $ </tex-math></inline-formula> in the H-plane array. Additionally, a broadside gain of 7.3 dB and 7.1 dB is achieved for a single port in the respective configurations. The proposed technique offers an effective, scalable, and space-efficient solution for high-isolation MIMO antenna systems, making it suitable for advanced wireless communication applications.
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institution Kabale University
issn 2169-3536
language English
publishDate 2025-01-01
publisher IEEE
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spelling doaj-art-e68f74692daf4d7b9db4d726c549a45b2025-08-20T03:25:02ZengIEEEIEEE Access2169-35362025-01-011310746710748110.1109/ACCESS.2025.358216211045917Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode ConversionManzoor Elahi0https://orcid.org/0000-0002-1049-2606Slawomir Koziel1https://orcid.org/0000-0002-9063-2647Leifur Leifsson2https://orcid.org/0000-0001-5134-870XEngineering Optimization and Modeling Center, Reykjavik University, Reykjav&#x00ED;k, IcelandEngineering Optimization and Modeling Center, Reykjavik University, Reykjav&#x00ED;k, IcelandSchool of Aeronautics and Astronautics, Purdue University, West Lafayette, IN, USAThis paper presents a novel self-isolation technique for multiple-input multiple-output (MIMO) microstrip patch antenna (MPA) arrays using annular via-based mode conversion. The proposed approach transforms the TM20 mode into a hybrid TM20+TM01 mode, enabling high isolation in both E-plane and H-plane coupled configurations without requiring additional decoupling structures. A compact <inline-formula> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> single-fed antenna array is designed using annular vias and an open slot in the MPA, serving as a fundamental unit for the MIMO array. By exciting an element with a hybrid mode in the H-plane coupled MIMO array, a TM10 mode of very low intensity is induced on the adjacent half and a TM01 mode on the rear half of the nearby patch that leads to high isolation. However, in the E-plane coupled MIMO array a quasi-TM01 mode is induced on each half of the nearby patch whose overall field distribution resembles a TM11 mode due to the slot in the patch and the annular vias. Thus, in both configurations, the coupled modes are either orthogonal or exhibit weak field distribution concerning the excited mode. To validate the technique, <inline-formula> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> MIMO arrays were fabricated and measured. An isolation levels of 38 dB and 40 dB is demonstrated in the E-plane and H-plane configurations, respectively, at 5.8 GHz. The measured cross-polarization level is &#x2212;50 dB in the broadside direction for the E-plane coupled array in both planes and it is 18 dB/23 dB at <inline-formula> <tex-math notation="LaTeX">$\phi =0^{\circ } $ </tex-math></inline-formula>/<inline-formula> <tex-math notation="LaTeX">$\phi =90^{\circ } $ </tex-math></inline-formula> in the H-plane array. Additionally, a broadside gain of 7.3 dB and 7.1 dB is achieved for a single port in the respective configurations. The proposed technique offers an effective, scalable, and space-efficient solution for high-isolation MIMO antenna systems, making it suitable for advanced wireless communication applications.https://ieeexplore.ieee.org/document/11045917/Microstrip patch antennamultiple-input multiple-outputisolationself-decoupling methodhybrid modecross-polarization
spellingShingle Manzoor Elahi
Slawomir Koziel
Leifur Leifsson
Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion
IEEE Access
Microstrip patch antenna
multiple-input multiple-output
isolation
self-decoupling method
hybrid mode
cross-polarization
title Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion
title_full Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion
title_fullStr Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion
title_full_unstemmed Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion
title_short Self-Isolation in MIMO Microstrip Patch Arrays Using Annular Via-Based Mode Conversion
title_sort self isolation in mimo microstrip patch arrays using annular via based mode conversion
topic Microstrip patch antenna
multiple-input multiple-output
isolation
self-decoupling method
hybrid mode
cross-polarization
url https://ieeexplore.ieee.org/document/11045917/
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AT slawomirkoziel selfisolationinmimomicrostrippatcharraysusingannularviabasedmodeconversion
AT leifurleifsson selfisolationinmimomicrostrippatcharraysusingannularviabasedmodeconversion