Multiple-input Multiple-output Antenna Design Research Articles

A Compact Planar Monopole UWB MIMO Antenna Design with Increased Isolation for Diversity Applications

A compact planar multiple input multiple output (MIMO) antenna with four elements spanning the ultra-wideband (UWB) is proposed for diversity applications. The unit cells are positioned orthogonally to lower the mutual coupling by replicating the single antenna three times. A 35 × 35 × 1.6 mm3 UWB MIMO antenna is provided with a 50-Ω impedance microstrip line on a 1.6-mm thick FR4 substrate. In the radiator and ground plane, some modifications are made to achieve the operating limits of this antenna between the frequencies of 3.1-10.6 GHz, thereby covering the entire frequency spectrum of the UWB with compact size. We conclude from the calculated results that the proposed antenna has high performance characteristics appropriate for UWB wireless indoor communication and diversity applications with compact size.

Design of Low-Profile Compact MIMO Antenna on a Single Radiating Patch Using Simple and Systematic Characteristic Modes Method

This article designs a class of low-profile compact multiple-input–multiple-output (MIMO) antennas on a single radiating patch using simple and systematic characteristic modes (CMs) method. Rather than using conventional method of radiation pattern and polarization diversities, this work demonstrates that by taking advantage of a proper superposition of some even/odd modes, it is able to generate similar radiation pattern and polarization no matter which port is excited. It is also found that port isolation and impedance matching are dependent on not only operating modes but also input couplings. The proposed CMs method consists of three main steps. First, adjust desired even and odd modes to be equal in resonant frequency (ResF). Second, suppress unwanted modes without affecting desired ones. Lastly, determine feeding positions to obtain proper input couplings. In this way, satisfactory port isolation and impedance matching could be achieved simultaneously and quickly, getting rid of complicated decoupling structures and time-consuming optimization. To exemplify how the proposed CMs method works, two MIMO antennas are successfully designed by just using simple slots and shorting pins. A prototype for the proposed four-port MIMO antenna is fabricated and measured for validation.

Analysis of Wave Propagation Models With Radio Network Planning Using Dual Polarized MIMO Antenna for 5G Base Station Applications

Dual polarized printed multiple input multiple output (MIMO) antenna for Band 42 (3.4 - 3.6 GHz) with wave propagation models is presented. Polarization and spatial diversity are achieved by utilizing two printed bow-tie antennas in orthogonal orientation. The designed dual polarized antenna element with <inline-formula> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> massive MIMO antenna configuration radiation patterns are deployed in selected geographical situation for detailed radio network planning using FEKO-WinProp platform. Knife edge diffraction, extended walfisch-ikegami and dominant path wave propagation models are implemented with designed MIMO antenna configurations. Modulation schemes of QPSK and QAM with corresponding data rates and throughput for all propagation models are presented. The signal strength and quality reflecting parameters reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and signal to noise plus interference ratio (SNIR) are also evaluated for each model. From the simulation results dominant path model provides data rate and throughput of 3.827, 995 MBit/s and 3.577, 930.1 MBit/s for single stream of data in uplink and downlink respectively. The maximum data rate of 1.37 GBits/s is achieved for deployed base stations with <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> massive MIMO antenna configuration effectively covering the entire geographical site.

H-Shaped Eight-Element Dual-Band MIMO Antenna for Sub-6 GHz 5G Smartphone Applications

The design of an eight-element H-shaped dual-band multiple-input multiple-output (MIMO) antenna system for sub-6 GHz fifth-generation (5G) smartphone applications is presented in this work. The radiating elements are designed on the side edge frame of the smartphone, placed on both sides of the main printed circuit board (PCB). Each side edge consists of four radiating elements, which ensures low mutual coupling between antenna elements. The total size of the main PCB is 150&#x00D7;75 mm², while the size of the side edge frame is 150&#x00D7;7 mm². A single antenna consists of an H-shaped radiating element fed using a 50&#x03A9; microstrip feeding line designed on the main board of the smartphone. The results show that, according to -6 dB impedance bandwidth criteria, the designed MIMO antenna radiates at two different frequency ranges within the allocated FCC 5G spectrums, i.e., 3.1-3.78 GHz and 5.43-6.21 GHz with 680 MHz and 780 MHz bandwidths, respectively. It is also observed that the antenna elements are able to provide spatial and pattern diversity for both the frequency bands. Furthermore, an isolation of &#x003E;12 dB is observed between any two given radiating elements. Various MIMO key performance parameters are evaluated, such as channel capacity (CC), envelope correlation coefficient (ECC), and diversity gain (DG). A prototype is fabricated and measured, and it is found that the measured and simulated results are in good agreement. Based on performance attributes, it can be said that the proposed MIMO system may find its application in 5G communication systems.

Multiple input multiple output (MIMO) and fifth generation (5G): an indispensable technology for sub-6 GHz and millimeter wave future generation mobile terminal applications

AbstractThe in-depth exploration in the future 5G technology symbolizes a revolution in technology for antenna designers to encounter the all time increasing need as well as demand for higher data rate wireless communications. The paper gives out an exhaustive review of the evolution and characteristics of the 5G spectrum allocations, the MIMO antenna design with regard to mutual coupling reduction techniques and safer user applications. It precisely covers almost all the aspects of 5G which mainly include the types of antenna designs and their performance parameters related to MIMO design. The paper also presents a brief description of massive MIMO technology for base station applications. The main aim of the paper is: (1) to emphasize the frequencies allocated for the 5G including sub-6 Ghz and mm-wave bands; (2) to underline the suitable antenna designs for MIMO applications for mobile devices and base stations; (3) to highlight the mutual coupling effects in MIMO designs and its reduction techniques; (4) to consider the gaps in the literature and the challenges for reducing SAR effects for the safety of the users. This review paper has been an attempt to explore the evolution of 5G bands and antenna designs for 5G applications, comparison based on the literature, and the techniques implemented for enhancing the MIMO antenna performances.

An enhanced design of a 5G MIMO antenna for fixed wireless aerial access

A recent market prediction is that 5G Fixed Wireless Access (FWA) will more than double over the next five years and trials at the same period in London suggest promising results. However, the shift to 5G FWA has raised a new set of research challenges in relation to speed of deployment and re-deployment, coverage, power consumption, end user mobility and last mile connectivity, to name just a few, because of the much higher expectations. A recent review reveals that key 5G Physical Layer technologies that will enable wide mobile and FWA have not kept up pace. In response to some of those research challenges, this paper presents the design of a 5G Multiple Input Multiple Output (MIMO) Antenna that is mounted on a tethered aerostat, and the combination of which serves as a 5G FWA aerial station. The antenna design features several novelties and the aerial station can provide last mile connectivity to a wide coverage footprint, with moderate power consumption and operating at high speeds. Both the evaluation of the antenna performance using several key performance indicators and the validation of the aerial station as a 5G FWA in a wireless sensor network (WSN) proof-of-concept application reveal efficiency gains.

Design of a compact UWB MIMO‐diversity antenna incorporating fractal inspired isolation structure with band notch characteristics

AbstractIn this communication, a new compact ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna with band notch characteristics is presented for wireless application. It comprises of two unique monopole antenna elements sharing a similar ground plane. To reduce the coupling between antenna elements, a modified T‐shaped stub equipped with Minkowski fractal shape elements are introduced on the ground plane which in turn establish a good isolation between radiating elements. A band notch is achieved at 5.45 GHz by adding two additional rectangular stubs at 45° where symmetric slots have been etched. The efficiency and gain of the antenna drops significantly at the centre of the notch band which indicates good interference suppression. Results show that the designed antenna delivers widest impedance bandwidth (−10 dB) throughout the operating band of 3.1–20 GHz (of 146% impedance bandwidth) which covers UWB as well as Ku‐band. The antenna also produces ‐18 dB isolation for most of the operating band and ‐16 dB up to 6 GHz. The optimized antenna is fabricated and tested showing |S11| characteristics below −10 dB from 3.1 to 20 GHz band. The dimension of the proposed antenna is 18 × 26 × 1.6 mm3. Results show that the simulated characteristics are in good agreement with the measured counterpart. The designed MIMO antenna is an appropriate candidate for UWB and other wireless applications.

Design and Fabrication Of Microstrip MIMO Antenna For 5G Smart Phones

Now a days, extensive research on the 5G technology is on the rise. With the commercialization of the fifth generation (5G) mobile communication, high data rate communication and intelligent wireless services is approaching. In this project a wide band eight element MIMO (Multiple Input Multiple Output) array with high element isolation enrichment for 5G metal frame smart phones is presented. We built a rectangular patch antenna with 56 radiation and 2×4 elements. The MIMO microstrip antenna with 112 radiation using the microstrip feedline is designed for 5G wireless communication. The 2×4 MIMO microstrip antenna provides excellent results with a bandwidth impedance of 0.7GHZ and access to recovering 32dB loss to 7GHZ. The designed MIMO antenna array comprises of T shaped and inverted T shaped slots. To improve the bandwidth, the required resonances can be obtained by adjusting the E shaped slots. Furthermore, to improve the element isolation between two antennas, L and T shaped slot is introduced between each antenna element.

Split Ring Resonator-Based Bandstop Filter for Improving Isolation in Compact MIMO Antenna.

The ever-growing expectation for high data rates has led to the introduction of multiple-input multiple-output (MIMO) technologies to wireless connectivity. Such a system requires an MIMO antenna with high isolation. At the same time, the MIMO dimension should not be compromised for achieving high isolation. Thus, isolation techniques that do not allow an increase in dimension need to be fostered for MIMO antenna design. In this paper, a novel low-profile, miniaturized MIMO antenna with high isolation was developed considering a split ring resonator (SRR)-based bandstop filter as a decoupling network. The bandstop filter was designed with a unit cell split ring resonator structure and was deployed between two closely spaced monopole MIMO antenna elements to obtain isolation as high as 39.25 dB at 2.61 GHz. Two open-circuit stub lines were attached with the MIMO feeding network to achieve good impedance matching at resonance frequency. The proposed antenna exhibited a peak gain of 3.8 dBi and radiation efficiency of 84%. It had a low envelop correlation coefficient (ECC < 0.12), high diversity gain (DG > 9.95 dB), low mean effective gain ratio (MEG 1/MEG 2 < 0.05 dB), and low channel capacity loss (CCL < 0.042 bits/s/Hz) at resonance frequency. The overall antenna dimension was restricted to for its easy integration in compact wireless devices.

Design of an interlocked four-port MIMO antenna for UWB automotive communications

AbstractThe design, analysis, fabrication, and testing of a four-port multiple-input multiple-output (MIMO) antenna is reported in this paper for automotive communications. The MIMO antenna is constructed using the basic antenna element exploiting a slot geometry. Two such antennas are developed on the same microwave laminate to develop a two-port MIMO antenna. Two such microwave laminates are interlocked to create the four-port MIMO scheme. The most distinct feature of the proposed architecture is that the inter-port isolation is well-taken care without the need for an external decoupling unit. The four-port MIMO antenna has an overall volume of 32 × 15 × 32 mm3. The prototype MIMO antenna is fabricated and the measurements are carried out to validate the simulation results. The antenna offers ultra-wideband (UWB) characteristics covering the frequency range of 2.8–9.5 GHz. The average boresight gain of the antenna ranges from 3.2 to 5.41 dBi with the peak gain at 8 GHz. The simulated efficiency of the antenna is greater than 73% within the operating bandwidth. The MIMO parameters such as envelope correlation coefficient, diversity gain, and mean effective gain are evaluated and presented. The appropriateness of the proposed antenna for deployment in the shark fin housing of the present-day automobiles is verified using on-car performance estimation.

An Efficient Optimization Scheme for MIMO Antenna Decoupling Networks Using Space Mapping Techniques

The design of multiple input multiple output (MIMO) antennas using decoupling networks (DNs) often requires optimization and is computationally time consuming when using full electromagnetic solvers. To reduce the computational cost, the use of space mapping (SM) techniques in MIMO antenna design is proposed. Two approaches are considered for developing the necessary SM coarse model for MIMO antennas. The first is based on conventional DNs while the second uses a novel application of the internal multiport method (IMPM). Various parameter extraction (PE) techniques for SM techniques suitable for MIMO DN design are also developed. Two MIMO antennas are optimized to demonstrate the effectiveness and efficiency of the proposed schemes. Compared to conventional optimization, the proposed schemes improve the optimization speed by factors of approximately 20 and importantly, meeting the antenna design specifications for all examples.

MIMO Antenna for IEEE 802.11ac with Cross-Polarized Circular Configuration of Printed Yagi Elements

Antennas characteristics contribute significantly to Multiple Input Multiple Output (MIMO) system performances. IEEE 802.11ac is a wireless technology standard supporting transmission data rate of up to 1 Gbps by implementing the MIMO system. The design of the antenna should be capable to support the achievement of high channel capacity. This paper proposes the design of MIMO antenna for IEEE 802.11ac access point. The proposed MIMO antenna is composed of eight Printed Yagi elements, and each one has a bandwidth covering the frequency band of the IEEE 802.11ac system. In order to ensure a low coupling level between elements, the cross-polarized arrangement is used. In order to achieve good coverage for the area around the access point, the circular arrangement of Printed Yagi elements has been chosen as the solution referring to the problem. Computer simulations and laboratory measurements have been performed in achieving the design of the proposed antenna. Simulation and measurement results show that the proposed MIMO antenna has been able to support channel capacity of up to 1 Gbps at the low Signal to Noise Ratio (SNR) conditions of 10 dB.

Design of Compact High-Isolation MIMO Antenna With Multiobjective Mixed Optimization Algorithm

Integrating particle swarm optimization (PSO) and binary PSO into multiobjective evolutionary algorithm based on decomposition (MOEA/D) by group operator in parallel, an improved mixed optimization algorithm MOEA/D-M is proposed as an automation design scheme for compact high-isolation multiple-input–multiple-output (MIMO) antenna design. When the algorithm runs, each particle has several neighboring particles and all the particles are subdivided into a few groups. Both groups and neighborhoods provide helpful or potential information to their members. Then, under predefined constraints, MIMO antenna with anticipated performance can be generated intelligently and targetedly. The effectiveness of this design scheme is demonstrated by a single-band and a dual-band compact high-isolation MIMO antenna design for wireless local area network (WLAN)/world interoperability for microwave access (WiMAX) applications sharing the same initial reference model. The design degree of freedom of MIMO antennas may be increased greatly with the proposed design technique.

Coupling reduction using a novel circular ripple-shaped decoupling mechanism in a four-element UWB MIMO antenna design

A 4*4 multiple-input multiple-output (MIMO) antenna with compact size and good isolation is presented for UWB applications. The concept of polarization diversity is here discussed and employed to satisfy contemporary wireless communication systems requirements. In the proposed antenna, the utilization of a novel circular ripple-shaped decoupling structure and a matching structure are presented to minimize mutual coupling of the inter-elements and enhance adaptation. Experimental results show a bandwidth range from 2.96 to 11.4 GHz with a good reflection coefficient which is S 11 < −12 dB, high isolation S 21 and S 31 < −20 dB, good Envelope Correlation Coefficients ECC21 and ECC31 < 0.03, Diversity Gain DG21 and DG31 equal to 8.75, and a Total Active Reflection Coefficient (TARC) less than −12 dB. The antenna also exhibits a maximum gain of about 4 dBi with a maximum efficiency of 70% which proves that this antenna is a potential candidate for UWB applications.

Design and analysis of a compact UWB MIMO antenna incorporating fractal inspired isolation improvement and band rejection structures

This paper numerically proposes and experimentally investigates a compact coplanar waveguide fed two element ultra-wideband (UWB), multiple-input–multiple-output (MIMO) antenna array accompanying peak isolation and triple band notch mechanism. The proposed antenna consists of two identical printed monopole elements along with the incorporation of multiple 2nd order Hilbert defects in the ground structure and proposes to incorporate three different mechanisms to reduce the electromagnetic interference of the UWB antenna with existing narrowband systems. The measured impedance bandwidth for the intended antenna ranges from 2.7 GHz to 11.22 GHz. The incorporation of notch mechanisms provides interference suppression at the C-band (3.7–4.2 GHz), WLAN (5.15–5.825 GHz), and X-band communication (7.9–8.4 GHz). The overall size of the intended UWB MIMO antenna is 30.75 mm × 37.80 mm. Moreover, the diversity parameters of the proposed UWB MIMO antenna are numerically calculated and empirically investigated, these calculations and investigations depicts high diversity performance. It is noteworthy to observe that the spacing between the elements is staggeringly reduced to 2 mm. The concurrence among the diverse numerical and experimental outcomes supports the candidature of the suggested layout for portable UWB as well as UWB MIMO systems.

Design of a wearable MIMO antenna deployed with an inverted U-shaped ground stub for diversity performance enhancement

AbstractA compact multiple input multiple output (MIMO) antenna operating at 2.45 GHz industrial scientific and medical band is presented for wearable devices. Open-end slotting is used to miniaturize the antenna dimensions. Inverted U-shaped ground stub is incorporated to reduce mutual coupling. On-body performance is analyzed on a three-layered equivalent tissue phantom model. The wide bandwidth of 300 MHz and port isolation of 30 dB are obtained from measured results. The antenna shows the efficiency of 40% and directivity of 4.56 dBi when placed at a gap of “s” = 4 mm from the body. Broadside radiation pattern and low specific absorption rate make the antenna suitable for on-body communication. Further, diversity performance is measured in terms of envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL). The value of ECC is 0.025, DG is 9.98 dB, and CCL is 0.12 bits/s/Hz at 2.45 GHz. Antenna robustness is examined by bending the structure at different radii along the x-axis and y-axis. Performance of the proposed structure is reliable with structural deformation.

Design Issues and Challenges in Indoor MIMO Antenna Systems

The promising solution for next generation wireless communication system is multiple input multiple output (MIMO) system. It can transmit and receive data from different channels simultaneously without any need of additional frequency band. In this paper the design issues and challenges in MIMO antenna system for different applications have been reviewed. The major applications of MIMO systems include Wi-Fi, High Speed Packet Access, LTE, WiMAX (4G), and also MIMO has been used in power line communication. Implementation of MIMO antenna system is dependent on important parameters such as: Peak gain, Average Gain, Mutual Coupling, Envelop Correlation Coefficient (ECC), Total Active Reflection Coefficie nt (TARC), Signal polarization and Miniaturization of antenna system. Hence an optimal MIMO antenna design to suit for communication applications in an indoor environment is a challenging task. This paper proposes comparative study for the different MIMO antenna parameters. The different modeling techniques for MIMO antenna system are surveyed and areas for future research work in line with tradeoffs between different design parameters are suggested.

Design and development of triple-band compact ACS-fed MIMO antenna for 2.4/3.5/5 GHz WLAN/WiMAX applications

In this paper, a very small size (20 × 14.75 mm2) triple-band multiple-input multiple-output (MIMO) microstrip patch antenna for WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz) wireless applications. The goal of this paper is to merge these two wireless standards into a single antenna that can be easily accommodated inside the devices operating in three different frequency ranges. The proposed MIMO antenna consists of an asymmetric coplanar strip (ACS) feedline loaded with an inverted L-shaped slot and a meanderline. The inverted L-shaped slot and the meanderline both having an electrical length 0.5λ, are responsible for the achieving the operating band around 3.5 and 2.4 GHz, respectively whereas the ACS feedline is responsible for the generation of 5 GHz frequency band. The fabricated prototype of the proposed MIMO antenna when tested, shows three distinct frequency bands; I from 2.38 to 3.00 GHz, II from 3.21 to 3.61 GHz and III from 5.02 to 6.18 GHz that covers entire frequency bands of WLAN and WiMAX wireless applications along with different standards of IEEE 802.11 including a/b/j/p/g/n/ac/ax. The peak gain in I, II and III frequency bands is 7.93, 4.23 and 7.57 dBi, respectively. In addition, the diversity performance in terms of envelope correlation coefficient, diversity gain, multiplexing efficiency, total active reflection coefficient, and mean effective gain is also performed for the proposed MIMO antenna.

Mutual coupling reduction in Chinese character‐shaped artistic MIMO antenna

AbstractIn this paper, a Chinese character‐shaped artistic multiple input multiple output (MIMO) antenna with H‐shaped defect ground structure (HDGS) is designed and analyzed. The H‐shaped structures are loaded on the ground along the outer edge of patches to make it a part of the coupling current propagation direction. The two‐element MIMO antenna is placed on the substrate with a separation of only 0.024 λ0 (λ0 is the free‐space wavelength at 2.458 GHz). The designed MIMO antenna without HDGS has 10.4 and 7.2 dB higher isolation than E‐ and H‐plane rectangular array antennas. After loading HDGS, the isolation reaches 23.86 dB at 2.458 GHz, and the center frequency is not offset. The achieved bandwidth is within IEEE 802.11 at a 2.4‐GHz wireless local area network band. Meanwhile, the isolation is higher than 20 dB in the 10‐dB impedance bandwidth (2.447‐2.468 GHz). Moreover, the radiation pattern remained basically unchanged.

High-Isolated MIMO Antenna Design Based on Pattern Diversity for 5G Mobile Terminals

In this letter, a novel multiple-input–multiple-output (MIMO) antenna operating at 3500 MHz band is presented for 5G mobile terminals. The proposed antenna includes four blocks. Each block consists of two face-to-face elements with total size of 25 × 3.5 mm2. Rather than excited separately, the two elements are excited simultaneously. Pattern diversity is achieved by using in-phase and out-of-phase signals. A compact two-port feed network is designed to provide the required feed signals. The measured bandwidth for the two ports is 750 MHz (3.06–3.81 GHz) and 340 MHz (3.33–3.67 GHz), which is sufficient to cover the 3400–3600 MHz band. The port isolation is higher than 14 dB in the overlapping bandwidth.