Mutual Coupling Reduction Research Articles

Mutual coupling reduction of two-port dielectric resonator MIMO antenna using defected ground structure

Abstract This article focuses on reducing mutual coupling between the ports of dielectric resonator antenna (DRA) using defected ground structures (DGSs). The antenna has the dimension of 50 mm × 50 mm × 8.5 mm. The resonating element in the proposed two-port radiator consists of a cylindrical structure of alumina ceramic (ɛr = 9.8). The rectangular-shaped aperture is utilized to excite both of the resonating elements. The resonating ceramic elements acting as radiators are offset-fed to enhance the antenna’s coupling. Combining interdigital-shaped and semicircular arc-shaped DGSs improves isolation between two resonating elements, embodying the structural novelty. The measured operating frequency range of Port-1 and Port-2 is 5.19–6.7 and 5.15–6.68 GHz, resonating at 5.58 and 5.56 GHz, respectively. The measured mutual coupling between the two ports is −35.5 dB. The measured gain for Port-1 is depicted to be 5.5 dB. The presented multiple-input–multiple-output (MIMO) radiator in this article is an appropriate candidate for WLAN (5.25–5.35, 5.47–5.725, 5.725–5.85, 5.850–5.925 GHz) and WiMAX(5.5 GHz) applications. All the simulated and experimentally observed MIMO parameters of the radiator are discovered to be within optimal bounds.

A Review of Isolation Techniques for 5G MIMO Antennas

This paper offers an analysis of mutual coupling reduction techniques used in MIMO antennas designed for sub-6 GHz, 28 GHz, and 28/38 GHz dual frequency bands which are allocated to 5G technology. The said techniques take into account size, gain, isolation, and all diversity-related parameters, such as envelope correlation coefficient (ECC), directive gain (DG), and channel capacity loss (CCL). A review of current technologies is presented in the paper too. The isolation techniques are studied in detail and comparisons between the various works are drawn. Finally, the best isolation technique suitable for specific bands, applications and different port numbers is determined.

Compact dual-band enhanced bandwidth 5G mm – wave MIMO dielectric resonator antenna utilizing metallic strips

A compact dual-band Multiple-Input Multiple-Output Dielectric Resonator Antenna with improved bandwidth for 5G mm-wave applications is presented. Two rectangular DRAs mounted on a substrate backed ground plane are excited by microstrip feed through aperture coupling. Notches cut out from center of the DRAs helps to achieve a dual-band response with improved bandwidth by exciting several modes. The isolation between the DRAs is achieved by appropriately positioning metallic strips on walls on of the DRAs. A dual-band response with enhanced bandwidth and mutual coupling reduction. The impedance bandwidth for the proposed design is between 26.5–30 GHz (12.4 %) and 34.2–40 GHz (15.6 %). The maximum isolation achieved in the lower band is 32 dB and above 45 dB in the upper band. The overall size of the design is 1.88λo x 0.94λo x 0.20λo. The design procedure is described, and the role of decoupling strips are explained. A prototype is fabricated and measured to validate the proposed design.

Radiation Behavior of Synthesized LiTi Ferrite Based Microstrip Antenna in X Band

The paper comprehensively explores the development, characteristics, and antenna applications of lithium titanium (LiTi) ferrite. Utilising a solid-state reaction technique, the study examines the substrate’s electrical, magnetic, and structural properties in detail. Additionally, it assesses the far-field radiation patterns of a magnetically-biased LiTi ferrite-based antenna. Key findings point to a noticeable reduction in mutual coupling and radiated power, along with an isotropic redistribution of minor side lobes. Comparative analysis with RT-duroid substrates in X band frequency spectrum highlights the LiTi ferrite-based antenna’s remarkable 62.85 % miniaturization and consistent directivity, along with a superior quality factor. These findings emphasise LiTi ferrite’s potential for compact, high-performance applications in demanding environments. LiTi ferrite’s advantages in miniaturisation and stability position it for specific applications, despite trade-offs in bandwidth, gain, and impedance compared to RT-duroid substrates.

Design and performance analysis of compact quad‐band two‐port sickle‐shaped MIMO antenna for wireless applications

AbstractIn this research, a quad‐band sickle‐shaped MIMO antenna of compact size 32 × 32 mm2 (0.28λ0 × 0.28λ0 at lower resonant frequency 2.6 GHz) has been proposed using partial ground and tilted isolation stub at an angle of 45°. It covers 2.40 to 2.80 GHz frequency range with bandwidth (BW) of 15.38% (0.40 GHz) which is applicable for Wi‐Fi application in first band and in second band it covers from 4.48 to 5.75 GHz frequency range with BW of 24.83% (1.27 GHz) for WLAN application. In addition, the third band starts from 9.75 to 10.43 GHz frequency range with BW of 6.74% (0.68 GHz) for the X‐band whereas in fourth band it covers from 13.07 to 15.87 GHz frequency range with BW of 19.38% (2.8 GHz) frequency, which is applicable on Ku‐band application. Moreover, the isolation is < −15 dB in the entire resonating frequency band which is an acceptable limit for reduction of mutual coupling. ECC value is <0.5 in the entire operating band of frequency. The diversity gain of the proposed MIMO antenna is approximately 9.96 dB that shows the antenna exhibits good diversity property. The channel capacity loss value is <0.4 bps/s/Hz in the entire resonating band. In view of all the diversity parameters, the proposed MIMO structure fulfills all the requirements of the MIMO antenna.

Four-port dual-band textile MIMO antenna for biomedical health monitoring systems: on-body mutual coupling reduction characterization

The paper outlines a methodology to diminish mutual coupling in 4-port dual-band MIMO textile antenna for biomedical applications. This antenna leverages MIMO technology and Wireless Body Area Network (WBAN) for operation in two distinct frequency bands at (3.5 & 2.45 GHz). The antenna is made up of four octagonal patch antennas, each having a bar and a split-ring (SR) slot with 47.2 × 31 mm2 dimensions for each patch. A hybrid mutual coupling (MC) approach was investigated with closely spaced patches (up to 0.05λ). Various bending setups have been selected along with flat case to examine the antennas’ resilience which demonstrate such agreement between measured and simulated findings. Furthermore, the MC is only −20 dB, the envelope correlation coefficient (ECC) is 0.001, and maximum peak measured gain of 5.2 dBi is achieved with lowest peak specific absorption rate (SAR) value. Even when bent at a 60° angle along with y-axis and x-axis, the antenna retains a decent gain of 1.861 dBi in the low frequency region and 5.479 dBi at high frequency band. Surprisingly, the antenna outperforms the attenuation produced by the lossy effects of the human body, indicating a favorable alignment between the modelled and observed findings.

Design of a Compact Multiband Monopole Antenna with MIMO Mutual Coupling Reduction.

In this article, the authors present the design of a compact multiband monopole antenna measuring 30 × 10 × 1.6 mm3, which is aimed at optimizing performance across various communication bands, with a particular focus on Wi-Fi and sub-6G bands. These bands include the 2.4 GHz band, the 3.5 GHz band, and the 5-6 GHz band, ensuring versatility in practical applications. Another important point is that this paper demonstrates effective methods for reducing mutual coupling through two meander slits on the common ground, resembling a defected ground structure (DGS) between two antenna elements. This approach achieves mutual coupling suppression from -6.5 dB and -9 dB to -26 dB and -13 dB at 2.46 GHz and 3.47 GHz, respectively. Simulated and measured results are in good agreement, demonstrating significant improvements in isolation and overall multiple-input multiple-output (MIMO) antenna system performance. This research proposes a compact multiband monopole antenna and demonstrates a method to suppress coupling in multiband antennas, making them suitable for internet of things (IoT) sensor devices and Wi-Fi infrastructure systems.

Mutual Coupling Reduction of Super Wide Band MIMO Antenna Using Metamaterial Periodic Defected Ground Structures for THz Applications

Mutual Coupling Reduction of Super Wide Band MIMO Antenna Using Metamaterial Periodic Defected Ground Structures for THz Applications

Ultra-Compact 4-Port MIMO Antenna with Defected Ground Structure and SAR Analysis for 28/38 GHz 5G Mobile Devices

To tackle the challenge of keeping 5G mobile devices compact while supporting millimeter-wave bands, we've created an ultra-compact 4-port dual-band MIMO antenna with a defected ground structure (DGS). This design minimizes mutual coupling and covers a broad frequency range. Built on a Rogers TMM4 substrate with dimensions of 17.76×17.76 mm2, the antenna includes four planar patch antennas positioned perpendicularly at the corners. Each antenna operates at 28/38 GHz and features a rectangular patch with four rectangular slots and a full ground plane. The patches are separated by 0.5 λo, with the DGS further reducing mutual coupling. Both simulations and measurements indicate a significant reduction in mutual coupling (−39 to −60 dB), improving ECC, TARC, MEG, and DG. Time-domain and SAR analyses confirm the antenna's efficiency and its suitability for 5G devices.

A Review on 5G Antenna: Challenges and Parameter Enhancement Techniques

The need for a high-speed mobile network has increased due to the COVID19 pandemic.5G is the newest and most sophisticated technology designed to handle the demands of the internet. The 5G network ensures connection security and simplifies mobile device connectivity to wireless devices. This paper explains every parameter related to 5G technology that has been covered in various papers. It addresses some of the difficulties that 5G technology faces. The development of Vivaldi, conformal, MIMO antennas satisfies the requirements of the 5G mobile network and presents opportunities to overcome obstacles. In the paper, MIMO antenna is discussed along with various techniques for enhancing its parameters, such as appropriate substrate selection, antenna element placement, and mutual coupling reduction. Different techniques like isolation, DGS, slot, metamaterial, neutralizing line, and frequency reconfigurations are explained under mutual coupling reduction techniques. A comparative analysis of various antenna feeding techniques is presented in the paper. The article provides details on how various parameters are affected by parameter enhancement techniques.

Development and comprehensive evaluation of a dual-port textile UWB MIMO antenna for biomedical use

In this paper, a textile two-port multi-input multi-output (MIMO) half-circle antenna with corrugated borders is designed and fully analyzed for nearfield ultra-wideband biomedical diagnostic applications. The orthogonal polarization technique is introduced for mutual coupling reduction, signal quality, and imaging accuracy improvement. A low pass filter with significant out-of-band rejection is inserted between the two MIMO structural elements to improve the isolation from element to element. For simple system integration, A 50 ohms feed coplanar waveguide is suggested for each element. The entire antenna is constructed using textile materials, with the radiating element composed of conductor fabric. The substrate, on the other hand, is crafted from cotton material which possesses a relative permittivity of and a tan δ value of 0.025. The size of each antenna element has low-profile dimensions of 40 × 40 × 0.3 mm3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${mm}^{3}$$\\end{document}. The measured results obtained demonstrate an extremely broad bandwidth extends from 2.5 GHz to 12 GHz. Omnidirectional radiation pattern is obtained, with 6 dBi maximum gain and 96% efficiency. In order to ensure flexibility, a range of bending conditions were analyzed, and the durability was assessed through wash ability testing. Safety was confirmed by measuring the specific absorption rate. Furthermore, time domain and MIMO performance assessments were performed to ensure its suitability for imaging systems.

High-accuracy 2D DOA estimation with three parallel sparse nested array

To improve the performance for two-dimensional (2D) direction of arrival (DOA) estimation in the presence of limited antennas in practice, we propose a novel three parallel sparse nested array with extended aperture and reduced mutual coupling. The proposed array consists of three subarrays where locations of antennas have closed-form expressions, to efficiently achieve increased degrees of freedom in difference coarray domain. The unit inter-antenna spacings and the displacements among subarrays are all expanded by D1, D2 or D3 fold for aperture extension and mutual coupling reduction in physical array domain. By exploiting the configuration, the two methods, i.e., BOMP-based and CMT-BCS-based methods, are further explored for high-precision but ambiguous angle estimation, and then the coprime-ness between the displacements is utilized to solve the angle ambiguities. Simulation results demonstrate the superiority of the proposed array and methods for 2D DOA estimation over the existing technologies.

Mutual coupling reduction of a two-port MIMO antenna using defected ground structure

In response to the escalating demand for high data rates and the expanding user base, multiple input multiple output (MIMO) technology has recently become of paramount importance in addressing the imperative for high-capacity communication systems aligned with emerging standards. In this paper, a single antenna element that achieves a wideband frequency coverage by adjusting the slots ‘dimensions and a satisfactory gain of 6.4 dBi is presented. To enhance the antenna's gain and capabilities, we introduced a MIMO antenna designed to operate within the frequency range of 36.8 to 40.9 GHz. The proposed MIMO antenna configuration consists of two-element arrays etched on a compact 25.94×26.76×1.3 mm³ Rogers RT/duroid 5880 substrate. While maintaining the operational band and enhancing gain, a critical challenge involving inadequate isolation between the two antenna elements is encountered due to the confined area. To effectively tackle this issue, a parametric study on the inter element distance between antennas is conducted and Defected Ground Structure (DGS) is implemented. This refinement results in a substantial 3.6 dB enhancement in isolation, which is found to be lower than -31 dB, a notable improvement in impedance matching, and a remarkable high gain of approximately 7.7 dBi is achieved. Besides, the analysis of the MIMO metrics demonstrates that they consistently fall within acceptable ranges, with the antenna showcasing an envelope correlation coefficient of approximately 0.005 and a commendable diversity gain of around 9.99 dB. The proposed antenna's combined attributes, including its compact, simple, and low-profile design, position it as a highly promising choice for 5 G communication system and future miniature devices intended for Internet of Things (IoT) applications.

Low mutual coupling miniaturized dual-band quad-port MIMO antenna array using decoupling structure for 5G smartphones

Maintaining the compactness of 5G smartphones while accommodating millimeter-wave (mm-wave) bands presents a significant challenge due to the substantial difference in frequency. To tackle this issue, we introduce a miniaturized quad-port dual-band multiple-input, multiple-output (MIMO) antenna with low mutual coupling (MC) and a considerable frequency difference. This quad-port MIMO antenna, built on a Rogers TMM4 substrate, measures 17.76 × 17.76 mm2 and boasts a dielectric constant of 4.5. It incorporates four planar patch antennas, positioned at the corners in perpendicular orientations. For dual-band operation at 28/38 GHz, each antenna element features a rectangular patch with four rectangular slots, complemented by a full ground plane. The spacing between these elements is 0.5 λo, and we've included a decoupling structure (DS) to minimize mutual coupling (MC) among the MIMO antenna elements with minimal complexity and cost. Simulation and measurement results reveal a significant reduction in mutual coupling between the array elements, ranging from − 25 to − 60 dB. As a result, we’ve developed the envelope correlation coefficient (ECC) and made advancements in the total active reflection coefficient (TARC), mean effective gain (MEG), and diversity gain (DG). The measured gains for this design are approximately 8.9 dBi at both 28 GHz and 38 GHz, with a radiation efficiency of nearly 93%. Furthermore, specific absorption rate (SAR) analysis confirms the MIMO antenna's suitability for smartphone handsets operating within the target frequency band.

Mutual coupling reduction between antennas array for 5G mobile applications

This paper introduces the design of a multiple-input-multiple-output (MIMO) antenna optimized for low-profile applications supporting sub-6 GHz fifth-generation (5G) wireless applications. We have started the design from a single antenna with a square patch shape, each antenna array is composed from 4-element radiators fed by using power dividers and quarter microstrip lines. Mounted on a single Rogers RT5880 substrate, the MIMO antenna functions at 3.5 GHz. In order to miniature and to decrease the mutual coupling between the both antennas array we have optimised a magnetic wall based on periodic structures permitting to decrease the mutual coupling between the both antenna array. The unit element from the wall was optimised, studied and validated in order to absorb the surface current and to enhance the isolation between the different radiating elements. The dimensions of the proposed MIMO antenna are 154×220×0.578 mm³. The MIMO antenna final circuit achieves a peak gain of 9 dBi and an isolation around -30 dB. The introduction of the magnetic wall permits to enhance the isolation between the antenna array from -20 dB to -30 dB at 3.5 GHz band. This advancement contributes to the overall performance improvement of the MIMO antenna system.

Correction to “Sparse Array Mutual Coupling Reduction”

Correction to “Sparse Array Mutual Coupling Reduction”

A Compact Multifrequency Broadband Dual-Antenna System With Mutual Coupling Reduction for Wi-Fi 6E Application

A Compact Multifrequency Broadband Dual-Antenna System With Mutual Coupling Reduction for Wi-Fi 6E Application

Compact body‐worn MIMO antenna with high port isolation for UWB applications

SummaryThis article investigates the mutual coupling reduction of a compact two elements wearable ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna. The ground plane of the proposed wearable MIMO antenna structure consists of three connected square ring‐shaped stubs and two rectangular slots of narrow height. These ground stubs and slots minimize the mutual coupling effect between antennas and provide high isolation. The suggested MIMO antenna functions from the 1.87 to 13.82 GHz frequency spectrum covering WLAN (2.4–2.484 GHz), UWB (3.1–10.6 GHz), and X band (8–12 GHz) with 152.32% fractional bandwidth. It sustains port isolation above 27 dB throughout the 2 to 13.82 GHz frequency band. Inside the whole working frequency band, the suggested antenna offers a tiny envelope correlation coefficient (ECC < 0.098), greater diversity gain (DG > 9.93 dB), minimum channel capacity loss (CCL < 0.32 bits/s/Hz), and slight magnitude variation in mean effective gain of antenna ports (< 0.1 dB). The recommended antenna yields a SAR level below the designated threshold (<1.6 W/kg), affirming its suitability for body‐worn applications. The designed MIMO antenna structure has an overall volume of 32 × 48 × 1.5 mm3.

Patch antenna mutual coupling reduction using a genetic algorithm

Many modern telecommunication systems use antenna arrays for beamforming, and data rates increase. Mutual coupling between antennas negatively affects such systems' performance, so reducing the mutual coupling is a relevant research topic. This paper aims to cover a program development for the automated synthesis of decoupling structures between printed radiators. The results of the synthesis of printed structures for the reduction of mutual coupling between microstrip antennas placed on one dielectric substrate have been presented. Several structures that reduce the mutual coupling between antenna elements have been designed using a genetic algorithm. The developed program allows decoupling structure synthesis automation using numerical modelling methods. While synthesizing the decoupling structures, the directional properties of the received two-element antenna arrays have been considered.

Mitigating mutual coupling effects on circular polarization for improved bandwidth in MIMO systems: A novel approach

An improved mutual coupling compensation in circularly polarized (CP) multi-input multi-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper. Using trimming approach, the mutual coupling (MC) between closely spaced DRA units at 0.3λ has been significantly reduced while axial ratio performance has been maintained. Mutual coupling reduction is obtained by trimming the DRA to ensure low mutual coupling below −20dB. The exclusive features of the proposed MIMO DRA include wide impedance matching bandwidth (BW), triple band circular polarization, and suppressed MC between the radiating elements. The impedance bandwidth matches perfectly with a triple band's 3 dB axial ratio (AR). It is designed with characteristic mode analysis with good agreement of the measurement that has been obtained. Using the probe feed method, the DRA and patch strip are coupled together to allow bandwidth widening of the pro-posed DRA. An impedance bandwidth of 34% at a lower frequency to around 2% at a higher frequency was achieved in all resonance frequencies. Thus, we refer to our newly designed DRA as a proposed method for effectively reducing the mutual coupling between DRAs. Additionally, the 3 dB AR bandwidth matched at 3.3 GHz, 4.6 GHz, and 6.3 GHz with a percentage of 11.66%, 3.04%, and 2.22% obtained at the three different frequencies. Note that the proposed DRA exhibits low mutual coupling (below −20 dB) at the targeted frequencies, which is suitable for better signal reception for MIMO applications. By computing, the metrics envelop correlation coefficient, diversity gain, channel capacity loss, and total active reflection coefficient, the MIMO performance of the proposed antenna is verified. The experiments show a close result between simulated and computed validation of the proposed DRA.