Compact Multiple-input Multiple-output Antenna Research Articles

Compact wide band quad element MIMO antenna with inbuilt isolator for 5G applications

Abstract A compact quad-element multiple-input multiple-output (MIMO) antenna with self-isolation and pattern diversity features for 5G applications has designed in this article. In the proposed MIMO antenna design, drop-shaped slots have been cut from the ground plane to attain wide bandwidth of 1 GHz in the operating band 3.3-4.3 GHz of near radio (NR-77) band for 5G applications. Further, a criss-cross shaped isolator is formed after integrating four single wideband antenna elements with different orientations in the ground plane. This shape is responsible for high self-isolation of 25 dB in the desired band of 5G. Further, the 2-D radiation pattern of the MIMO antenna has pattern diversity characteristics with a high peak gain of 6 dB in the working band, which validates the proposed work for the 5G MIMO application. The diversity performance of the proposed MIMO antenna has been validated with measured envelope correlation coefficient of 0.0002, diversity gain of 10 and channel capacity loss is below 0.5 bits/sec/Hz across the entire frequency band. Furthermore, simulation studies have been demonstrated for different practical applications such as housing, automotive and on body for practical utility of proposed prototype.

A compact wideband MIMO antenna with efficient isolation for S and C-bands applications

This work explored a wideband Multiple Input Multiple Output (MIMO) antenna that has a compact rectangular shape, a rectangular stair slot, and a C-shaped metamaterial for isolation improvement. A wideband antenna has been developed and fabricated to determine the effectiveness of a specified metamaterial. To get minimum mutual coupling, the C-shaped metamaterial is positioned between the two rectangular antennas. According to the simulation, the MIMO antenna operates between 2.61 GHz and 7.64 GHz (5.03 GHz). Peak gain of the designed MIMO antenna from 3.4 to 9.1 dB. The envelope correlation coefficient (ECC) is < 0.03, diversity gain (DG) is > 9.99, mean effective gain (MEG) is < − 3 dB, and channel capacity loss (CCL) 0.005 is accomplished. The measured and simulated outcomes are in close acceptance of the performance parameter. Thus, the designed MIMO antenna is ascendancy for S and C-band applications such as Wi-Fi, Satellite up and downlink, and 5G.

Development and investigation of a compact band-notched MIMO antenna attaining wideband isolation for UWB applications

The sequential layout of a portable ultra-wideband (UWB) monopole antenna, transforming into a compact band-notch (3.15–4.3 GHz rejecting the Wi-Max and the C-Band) multiple-input multiple-output (MIMO) antenna is described in this paper. The diversity layout is designed within a compact size of 39 (l) × 18 (W) mm2. Due to the opposite orientation of the two radiators in the diversity configuration and the use of a rectangular parasitic strip near the feed lines, high and wideband isolation (of >20 dB) is attained over the entire UWB spectrum. The proposed layout depicts a stable omnidirectional radiation pattern and a maximal gain of 1.82 dB. The envelope correlation coefficient (ECC) is found to be below 0.18 for the entire UWB spectrum. Empirical verifications in terms of vital diversity parameters and analogy with competing layouts strengthen the candidature of the intended MIMO layout for UWB wireless portable applications.

Isolation enhancement of distinct element dual polarized compact MIMO antenna for 5G/WLAN application

AbstractA novel‐shaped dual‐polarized low‐profile multiple‐input multiple‐output (MIMO) antenna with high isolation is proposed for 5G/WLAN application. An 8‐element MIMO antenna design comprises two unique planar radiators (chamfer, circular). Each radiator has dual feed and dual polarization characteristics. The prototype is fabricated with an FR‐4 dielectric substrate. A decoupling structure maintains desirable isolation for self‐isolated elements (−12 dB) using substrate integrated waveguide stubs between inter‐ports and high isolation among the adjacent radiating elements (−15 dB). The simulation was performed by using CST microwave studio. The simulated results of the proposed MIMO antenna are compared with the measurement results. Furthermore, ECC and DG are investigated.

Compact ACS-fed MIMO antenna with dual-band notch characteristics for UWB applications

Abstract An ultra-wideband (UWB) and compact-size four-port multiple input multiple output (MIMO) antenna with a footprint of 34 mm × 34 mm fed by an asymmetric coplanar strip (ACS) is investigated. The proposed antenna is composed of four orthogonally placed identical modified elliptical-shaped radiators and achieves an impedance bandwidth of 3.4–12.2 GHz. By etching two inverted L-shaped slots in the radiator element, WLAN band and X-band are rejected in the operating communication range. Because of the usage of a meander line decoupler, the isolation enhancement at the 8–12 GHz band is achieved and the isolation is more than 18 dB for most of the UWB range. The performance of the proposed antenna is studied in terms of isolation between each port, radiation pattern, current distribution, gain, envelope correlation coefficient, diversity gain, and total active reflection coefficient. The compact size and reduced complexity make the proposed design highly suitable for portable devices.

Design process of a compact Tri-Band MIMO antenna with wideband characteristics for sub-6 GHz, Ku-band, and Millimeter-Wave applications

Design process of a compact Tri-Band MIMO antenna with wideband characteristics for sub-6 GHz, Ku-band, and Millimeter-Wave applications

Mutual Coupling Reduction in Compact MIMO Antenna Operating on 28 GHz by Using Novel Decoupling Structure.

This article presents an antenna with compact and simple geometry and a low profile. Roger RT6002, with a 10 mm × 10 mm dimension, is utilized to engineer this work, offering a wideband and high gain. The antenna structure contains a patch of circular-shaped stubs and a circular stub and slot. These insertions are performed to improve the impedance bandwidth of the antenna. The antenna is investigated, and the results are analyzed in the commercially accessible electromagnetic (EM) software tool High Frequency Structure Simulator (HFSS). Afterwards, a two-port multiple-input-multiple-output (MIMO) antenna is engineered by orthogonalizing the second element to the first element. The antenna offers good value for mutual coupling of less than -20 dB. The decoupling structure or parasitic patch is placed between two MIMO elements for more refined mutual coupling of the proposed MIMO antenna. The resultant antenna offers mutual coupling of less than -32 dB. Moreover, other MIMO parameters like envelop correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL) are also studied to recommend antennas for future applications. The hardware model is fabricated and tested to validate the results, which resembles software-generated results. Moreover, the comparison of outcomes and other important parameters is performed using published work. The outcome of this proposed work is performed using already published work. The outcomes and comparison make the presented design the best option for future 5G devices.

A compact bent microstrip-based wideband millimeter wave MIMO antenna for 5G applications

Abstract This paper proposes a wideband four-element multiple-input multiple-output (MIMO) antenna operating in the millimeter-wave frequency band for 5G communications from 24.37–39.44 and 45.09–50.62 GHz. The antenna design has been realized using Rogers 5880 substrate and consists of a T-shaped strip that is attached to the top of a 50 Ω feeding line. Two microstrip lines are affixed at the terminal points of T-shaped strip and bent toward the feeding structure. These bent strip lines are then extended by joining two additional L-shaped microstrip lines. On the back, there is a partial defective ground plane featuring a rectangular slot and a thin strip line located at its center. The dimensions of the proposed single element and MIMO antenna are 0.933λ × 0.933λ × 0.024λ and 1.865λ × 1.865λ × 0.024λ, respectively (at 28 GHz), while the edge-to-edge distance between the radiation elements of the MIMO antenna is 4.0 mm. The design incorporates an efficient passive fan-shaped decoupling structure to decrease coupling between antenna elements. Simulations and experimental results show good agreement with each other. For all resonant frequencies the measured peak gain is greater than 4.85 dBi, radiation efficiency is over 90%, diversity gain is greater than 9.5, ECC is less than 0.025, TARC is less than -10 dB and CCL is below 0.4 bits/s/Hz. The proposed MIMO antenna, with its wide bandwidth, high gain, high inter-port isolation, and high efficiency characteristics, can be used for 5G wireless communication applications.

Dual-Band MIMO Antenna with Four CPW Elements using Polarization Diversity for 5G Mobile Communication Networks and Satellite

In this paper, a novel design of compact quad-element MIMO (Multiple Input Multiple Output) antenna for 5G communication networks and satellites is proposed. The four similar elements of this antenna are placed perpendicularly to each other on a 40x40 mm2 FR4 substrate. Each element is fed by a CPW (coplanar waveguide) line. Two slits and an I-shaped slot are etched into the patch, and by varying their parameters; a good matching is achieved in the lower (4.9 GHz) and upper (17 GHz) frequency bands. However, 25 and 30 dB isolations are attained in the lower and upper bands, using the polarization diversity technique and adding stubs on the ground plane. A prototype of the proposed antenna is fabricated and measured. Moreover, the performance of the MIMO antenna is studied in terms of ECC (envelope correlation coefficient), DG (diversity gain), TARC (total active reflection coefficient), realized gain, efficiency, and radiation pattern, validated with the measured results, and showed a good agreement.

Mutual coupling reduction in a textile ultra-wide band MIMO antenna

This paper presents a mutual coupling reduction technique in a textile ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna system implemented on a textile substrate. The compact textile UWB MIMO antenna consists of two patch antennas implemented on a felt textile substrate. The compact size and close placement of the antennas in a MIMO system cause higher mutual coupling which deteriorates the performance of the communication systems. To minimize the mutual coupling, Parasitic Elements and Defected Ground Structures are used in the designed textile UWB MIMO antenna. The MIMO antenna performed very well over almost the whole UWB frequencies ranging from 3.29 GHz to 13.3 GHz. The simulated and the measured parameters showed a good impedance matching with an impedance bandwidth of 133.4%. The results showed an improvement of 20 dB isolation at certain frequencies without impacting the reflection coefficient S11 and the antenna impedance bandwidth. The MIMO antenna has good diversity performance parameters in terms of Envelope Correlation Coefficient (ECC), Diversity Gain, Mean Effective Gain (MEG) and radiation pattern and the results indicate that the textile antenna is suitable for UWB MIMO applications. The overall size of the antenna is 30x60 mm2. Fully embroidered structure provides freedom of movement and comfort, so it is a good fit for Wireless Body Area Network applications.

Miniaturized Four-Port MIMO Implantable Antenna for High-Data-Rate Wireless-Capsule-Endoscopy Applications

This study proposes a miniaturized four-port multiple-input multiple-output (MIMO) implantable antenna for wireless capsule endoscopy (WCE). The proposed MIMO implantable antenna operates in the 2.45 GHz industrial, scientific, and medical (ISM) band, has a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.2\,\, \times 5.2\,\, \times 0.127~\text {mm}^{3}$ </tex-math></inline-formula> , and comprises four meandered resonators sharing a common slotless ground plane with an acceptable bandwidth (14.2%) and low mutual coupling. These features help the antenna achieve high data rates and countering multipath distortions, as confirmed using MIMO channel parameters. The calculated link budget analysis of the proposed antenna suggests that seamless high-rate (78-Mbps) information transmission can be efficiently achieved over a distance of up to 10 m (when placed in the large intestine). The proposed MIMO implantable antenna was optimized by placing it inside a capsule comprising sensors, batteries, and electronic components and was subsequently fabricated. The simulated ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S$ </tex-math></inline-formula> -parameters, gain, and radiation patterns) and measured (in the minced pork) results were in close agreement with a measured bandwidth of 350 MHz and a peak measured gain of −20.1 dBi. To ensure patient safety, the specific absorption rate (SAR) was evaluated for all the four ports in different environments (stomach and small and large intestines), and satisfactory results were obtained. MIMO performance parameters, such as the envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity (CC), were also evaluated and acceptable values were noted. To the best of our knowledge, this is the most compact four-element implantable MIMO antenna designed so far for biomedical applications.

A Compact High-Isolation Four-Element MIMO Antenna with Asymptote-Shaped Structure

The demand for high-speed wireless communication systems has led to the development of ultrawide-band (UWB) antennas with a compact size and high performance. In this paper, we propose a novel four-port multiple-input multiple-output (MIMO) antenna with an asymptote-shaped structure that overcomes the limitations of existing designs for UWB applications. The antenna elements are placed orthogonally to each other for polarization diversity, and each element features a stepped rectangular patch with a tapered microstrip feedline. The unique structure of the antenna significantly reduces its dimensions to 42 × 42 mm2 (0.43λ×0.43λ@ 3.09GHz), making it highly desirable for use in small wireless devices. To further enhance the antenna's performance, we use two parasitic tapes on the ground plane at the back as decoupling structures between adjacent elements. The tapes are designed in a windmill shape and a rotating extended cross shape, respectively, to further improve the isolation. We fabricated and measured the proposed antenna design on a single-layer substrate (FR4) with a dielectric constant of 4.4 and a thickness of 1 mm. The measured results show that the impedance bandwidth of the antenna is 3.09-12 GHz, with an isolation of -16.4 dB, an envelope correlation coefficient (ECC) of 0.02, a diversity gain (DG) of 9.991 dB, an average total effective reflection coefficient (TARC) of -20 dB, an overall group delay value less than 1.4 ns, and a peak gain of 5.1 dBi. Although there may be some antennas that have better performance in one or two specific aspects, our proposed antenna has an excellent trade-off among all the antenna characteristics including bandwidth, size, and isolation. The proposed antenna also exhibits good quasi-omnidirectional radiation properties, making it well-suited for a range of emerging UWB-MIMO communication systems, particularly in small wireless devices. In summary, the compact size and ultrawide-band capabilities of the proposed MIMO antenna design, coupled with its improved performance compared to other recent UWB-MIMO designs, make it a promising candidate for 5G and next-generation wireless communication systems.

Compact Tightly-Coupled Self-Decoupled MIMO Antenna Using Internal Hybrid Tunning

This brief offers a compact, tightly-coupled, self-decoupled vias-based multiple-input multiple-output (MIMO) antenna pair with a common ground for a 5G system. The projected design comprises modified T-shaped tightly-coupled antenna elements. It is effortlessly helping to achieve sound decoupling across the desired band without using any extra decoupling circuit between the elements. It is revealed that the structure of the self-decoupled MIMO antenna tunes the inductive and capacitive (hybrid) effect of elements, which helps to achieve the decoupling of antenna elements. A relevant equivalent circuit model for coupled and decoupled MIMO antenna is proposed to validate the insight operation of this proposed theory. The hybrid tuning among the MIMO antenna elements reduces the coupling effect mutually by modifying the antenna shapes. The proposed self-decoupled MIMO antenna pair demonstrates low mutual coupling across the 5G NR frequency bands: n48 and long-term evolution (LTE) band 42/52 (3.2–3.6 GHz) with good diversity characteristics. Moreover, the one proposed design structure can offer dual-band self-decoupling features. The proposed structure provides 3.2-3.6GHz and 3.95-4.115GHz frequency bands. This structure can be optimize further to achieve dual-band/ wideband resonance in the design.

Compact Eight-Element MIMO Antenna with Reduced Mutual Coupling and Beam-Scanning Performance.

In this study, a multiple-input multiple-output (MIMO) antenna for wide scanning is designed. By adding slits to the patches, each element is intended to strengthen the isolation between the radiating elements. The proposed high isolation and wide scanning antenna combine to achieve the desired phased-array antenna. The array has a main beam pointing to the desired scanning region and a minimum side lobe level (SLL) in the undesired direction. A compact and linear eight-element array with an interelement spacing of λ/2 is designed and analyzed for beam scanning in the E-plane. Considering the worst case, the proposed array has a very low mutual coupling of (S21 = -24 dB), and it realizes a gain of 9.3 dBi and an SLL of 11 dB at a scanning angle of 70∘. The antenna performance was studied in terms of the S-parameter, radiation patterns, beam-scanning performance, envelope correlation coefficient (ECC), diversity gain (DG), peak gain, and efficiency. A close agreement was observed between the simulated and measured results.

Isolation Enhancement using CSRR Slot in the Ground for Compact Two-Element Textile MIMO Antenna

A textile integrated, two-element, multiple-input multiple-output (MIMO) antenna is designed for Wi-Fi, wireless local area network (WLAN), and wearable biomedical applications. A CSRR slot and horn-shaped decoupling structure increases impedance matching and reduces the current movement from one element of antenna to another element which increases the isolation to 7.4 dB. The CSRR slot in the ground is accomplished between the elements to mitigate the surface current and enhance the isolation up to 27.4 dB. The 10-dB radiation exists from 4.65 to 5.97 GHz with more than 20-dB isolation in the full operating band where the maximum isolation is found to be 49.45 dB at 4.7 GHz. MIMO parameters are investigated in a two-element antenna, in which acceptable results are obtained. Bending analysis and phantom analysis are performed for wearable applications which demonstrate the acceptable results.

Accelerated current-driven multi-objective topology optimization for compact ultrawide-band MIMO antenna design

In this work, an accelerated current-driven multi-objective topology optimization method is proposed for compact high-isolation ultrawide-band (UWB) multiple input multiple output (MIMO) antenna design. The proposed method takes the current Pareto solutions as the centers to perform fuzzy clustering (FC) and then drives the evolution of individuals in each cluster according to the current distribution characteristics of the clustering centers. Individuals in each cluster purposefully generate antennas with expected performance, thereby accelerating the process of optimization design. The proposed method uses about half the computational cost of traditional algorithms to design a compact (20 × 18 mm2) and high-isolation (>20 dB) UWB MIMO antenna. The proposed method provides a new way for accelerating multi-objective topology optimization with a high design degree of freedom. Also, the optimized antenna is a competitive candidate solution for UWB applications.

Compact UWB MIMO antenna with dual band-notch characteristics

ABSTRACT This article describes a quad-port ultra-wideband multiple-input multiple-output (MIMO) antenna with dual-band notch characteristics that is very compact and highly isolated. The compactness and high isolation of this design are achieved by etching a modified Minkowski fractal structure and an inverted L-shaped stub made available by the partial ground plane. Simply by incorporating ‘C’- and ‘U’-shaped slots in the radiating patch, it is possible to obtain dual-band rejection characteristics that are very suitable for wireless local area network band and X-band downlink satellite communication of 5.0–5.9 GHz and 7.1–7.9 GHz, respectively, in this proposed structure. The entire design is housed in a very compact size of 30 mm × 30 mm. A few key parameters, such as channel capacity loss (CCL), envelope correlation coefficient (ECC), diversity gain (DG) and total active reflection coefficient (TARC), are examined to ensure that the MIMO system meets its requirements. Furthermore, a mutual coupling value of less than −22 dB and an operating frequency band of 3.1–12 GHz allow the design to be very effective in a multipath channel environment.

Broadband Compact MIMO Antenna Employing CRLH Transmission Lines with High Isolation

A broadband and planar multiple-input multiple-output (MIMO) antenna with pattern diversity is presented in this letter. The four-port MIMO antenna is designed by using a novel metamaterial structure with small dimensions of 60 × 60 × 1.6 mm3. Each radiating element of the MIMO antenna is comprised of composite right/left-hand (CRLH) transmission lines (TLs). Between its four elements, there are four open L-shaped slot loading on the ground plane of the patch antenna system. The antenna obtains the wide frequency range of 2.31–4.99 GHz. In addition, The proposed antenna has an isolation greater than 20 dB between its four elements. The MIMO antenna has excellent bandwidth performance and good diversity properties between elements.

A Compact Four-Port MIMO Antenna for UWB Applications.

A compact four-port multiple-input multiple-output (MIMO) antenna for ultrawideband (UWB) applications is presented in this paper. The proposed antenna has four unit cell antennas. Each unit cell is placed orthogonal to its adjacent elements. The radiation element of each unit cell is composed of a cut semicircular patch and a stepped microstrip feed line. The whole ground on the back side consists of four parts of defective ground and their extended branches, which are connected through a “卍” structure. The main decoupling technology used in the MIMO antenna is polarization diversity. In addition, protruded ground and parasitic elements are added to achieve a higher isolation. This compact antenna has a small area of 45 mm × 45 mm and is printed on a single layer substrate (FR4) with an εr = 4.4 and a thickness of 1.6 mm. This antenna has an impedance bandwidth (S11 < −10 dB) of 3.1–13.1 GHz (123%) and an isolation of less than −17 dB. The envelope correction coefficient (ECC) is less than 0.02 and the average gain is 4 dBi. The ultrawide bandwidth and compact size of the proposed antenna make it a promising candidate for UWB applications.

A Compact MIMO Antenna for 5G NR Frequency Bands n257/n258/n261 Under Millimeter-Wave Communication

In this article, a compact, planar, 4-port ultra-wideband (UWB) multiple-input–multiple-output (MIMO) antenna is conceived for fifth-generation millimeter-wave applications. The suggested MIMO antenna architecture consists of four identical hexagonal-shaped slotted ground plane and four microstrip line feeds. The MIMO antenna's four components are arranged orthogonally to one another to provide a high level of inter-element isolation. The antenna prototype is constructed on a (12.5×12.5×0.8 mm3) Duroid 5880 substrate having a relative dielectric constant (ϵrsub) of 2.2 and loss tangent (tanδ) of 0.0009. Diversity characteristics such as envelope correlation coefficient (ECC), and diversity gain are determined to validate the proposed MIMO antenna's work qualities. The isolation is more than 18 dB, indicating that the proposed design is suitable for use as a quad-port MIMO antenna. The proposed MIMO antenna has a 30.47% impedance bandwidth throughout the frequency range of 26.7 GHz to 36.3 GHz, making it suitable for 5G New Radiofrequency bands n257/n258/n261 under Millimeter-Wave Communication. Positive correlations between the simulated and experimental findings are observed.