Review on the Design of the Isolation Techniques for UWB-MIMO Antennas

Ultra wide band - Multiple Input Multiple Output antenna technology provides higher data rates and the combination of the ultra wide band (UWB) and the multiple input multiple output (MIMO) technologies provides a solution for the demand of still higher data rates i.e. in excess of 3 Gb/sec in the future.  As the antenna technologies are improving, the size of the MIMO antenna is growing smaller and smaller. Placing the antenna elements in such close proximity increases the coupling between them. Various isolation techniques have to be introduced between the antenna elements to decrease the coupling and to improve the isolation. A study of the various isolation enhancement techniques have been made in this review. It analyses the various isolation enhancement methods such as using orthogonal polarization, parasitic elements, varied decoupling structures, defected ground structures (DGS), neutralization line (NL) and finally by using metamaterials. Metamaterials is a technology to perk up the isolation between the antenna elements. Split ring resonator (SRR) behaves as a metamaterial and it is used as an isolation mechanism in this study. The antennas are simulated and the results are compared. The method using parasitic elements gives the highest isolation of 35 dB and it is 5 dB better than the methods using orthogonal polarization and using the decoupling structure. The performance of all the antennas satisfies the conditions for minimum isolation. The envelope correlation coefficient is nearly zero in all the antennas and it implies good diversity performance. The diversity gain is also calculated for the various antennas and it satisfies good diversity performance. The bandwidth of the antennas is in the UWB frequency range and they have a fractional bandwidth above the required value of 1.09. The capacity loss for all the antennas is very low and the antennas using defected ground structure and the decoupling structure gives very low capacity loss

Mutual Coupling Reduction Techniques between MIMO Antennas for UWB Applications

The recent research has proved that the Multiple-input-multiple-output (MIMO) systems can substantially increase the channel capacity by employing multiple antennas at both the transmitter and receiver, without increasing either transmitter power or bandwidth. Hence it is very much essential to know all the aspects of MIMO system. Usually, in any MIMO system the antenna design plays a major role in improving the system performance and channel capacity. The antenna bandwidth must support the wireless system for transmitting larger data rates. Also, the mutual coupling effect between the antennas must be taken into consideration, while designing an efficient MIMO system. The objective of this paper is to discuss various techniques to reduce mutual coupling of MIMO antennas for UWB application

A Review on Different Techniques of Mutual Coupling Reduction Between Elements of Any MIMO Antenna. Part 2: Metamaterials and Many More

This two‐part article presents a review of different techniques of mutual coupling (MC) reduction. MC reduction is a primary concern while designing a compact multiple‐input‐multiple‐output (MIMO) antenna where the separation between the antennas is less than λ0/2, that is, half of the free‐space wavelength. The negative permittivity and permeability of artificially created materials/structures (Metamaterials) significantly help reduce MC among narrow‐band compact MIMO antenna design elements. In this part two of the review paper, we will discuss techniques: Metamaterials; Split‐Ring‐Resonator; Complementary‐Split‐Ring‐Resonator; Frequency Selective Surface, Metasurface, Electromagnetic Band Gap structure, Decoupling and Matching network, Neutralization line, Cloaking Structures, Shorting vias and pins and few more

MIMO antenna for mobile terminal

Dissertação para obtenção do Grau de Mestre em Engenharia Eletrónica de Telecomunicações e de ComputadoresNowadays there is a great demand for quality of service, higher bit rate and greater ef ficiency in mobile terminals, leading to technological advances in the world of telecom munications. MIMO technology makes use of multiple antennas in transmission and reception, allowing a higher data transfer rate and greater reliability without the need for extra power and bandwidth. In this MSc dissertation a planar IFA antenna was designed, which operates in the 2 Wi-Fi frequency bands of 2.4 GHz and 5 GHz. A MIMO system with 4 antennas based on the planar IFA, and its performance is analysed through key parameters such as correlation between elements, diversity gain and multiplexing efficiency. After the simulation and analysis of the system, a prototype was fabricated and measured in order to validate the coverage of the designated frequencies. The results achieved show that the designed antenna is feasible for WiFi applications, covering the intended frequency bands. In simulation the antenna obtains a good per formance in terms of MIMO parameters. A size/performance trade-off was applied to the final design, in favour of decreasing the size of the structure to make it possible to use it in smaller size devices.Nos dias de hoje existe uma maior exigência de qualidade de serviço, maior débito binário e maior eficiência nos terminais móveis, levando ao avanço tecnológico do mundo das telecomunicações. A tecnologia MIMO faz uso de múltiplas antenas na transmissão e na recepção, permitindo uma maior taxa de transferência de dados e uma maior fiabilidade sem a necessidade de aumentar a potência e largura de banda extra. Nesta dissertação de mestrado foi dimensionada uma antena IFA planar, que atua nas 2 bandas de frequência Wi-Fi de 2.4 GHz e 5 GHz. Um sistema MIMO com 4 antenas baseado nesta antena é concebido, sendo o seu desempenho analisado através de parâmetros chave, como a correlação entre elementos, ganho de diversidade e a eficiência de multiplexagem. Após a simulação e análise do sistema, foi fabricado e medido um protótipo de forma a validar o desempenho da antena projetada. Os resultados alcançados demonstram que a antena projetada é viável para aplicações WiFi, cobrindo as bandas de frequência pretendidas. Em simulação a antena obtém um bom desempenho em termos de parâmetros MIMO. Foi aplicado ao design final um compromisso dimensão/desempenho, em prol de diminuir o tamanho da estru tura para tornar possível a sua utilização em dispositivos móveis de tamanho mais reduzido.info:eu-repo/semantics/publishedVersio

An innovative fractal monopole MIMO antenna for modern 5G applications

Proposed in this paper is the design of an innovative and compact antenna array which based on four radiating elements for multi-input multi-output (MIMO) antenna applications used in 5G communication systems. The radiating elements are fractal curves excited using an open-circuited feedline through a coplanar waveguide (CPW). The feedline is electromagnetically coupled to the inside edge of the radiating element. The array's impedance bandwidth is enhanced by inserting a ground structure composed of low-high-low impedance between the radiating elements. The low-impedance section of the ground is a staircase structure that is inclined at an angle to follow the input feedline. This inter-radiating element essentially suppresses near-field radiation between adjacent radiators. A band reject filter based on a composite right/left hand (CRLH) structure is mounted at the back side of the antenna array to reduce mutual coupling between the antenna elements by choking surface wave propagations that can otherwise degrade the radiation performance of the array antenna. The CRLH structure is based on the Hilbert fractal geometry, and it was designed to act like a stop band filter over the desired frequency bands. The proposed antenna array was fabricated and tested. It covers the frequency bands in the range from 2 to 3 GHz, 3.4-3.9 GHz, and 4.4-5.2 GHz. The array has a maximum gain of 6. 2dBi at 3.8 GHz and coupling isolation better than 20 dB. The envelope correlation coefficient of the antenna array is within the acceptable limit. There is good agreement between the simulated and measured results.Dr. Mohammad Alibakhshikenari acknowledges support from the CONEX-Plus programme funded by Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 801538. Funding for APC: Universidad Carlos III de Madrid (Read & Publish Agreement CRUE-CSIC 2022)

Mutual Coupling Reduction for Dual-Band MIMO Antenna with Simple Structure

In this paper, a novel dual-band MIMO (multi¬ple input, multiple output) antenna for WLAN (wireless local area network) applications is presented. The MIMO antenna contains two dual-band antenna elements, each of which comprises a T-shaped monopole and a special ├-shaped stub resonator. Two operating bands with center frequencies of 5.5 GHz and 2.5 GHz are crested by the monopole of T shape and the stub resonator of ├ shape, accordingly. The ├-shaped stub also works as an isolation structure at the higher band, which can simplify the dual-band isolation design into a single-band problem. Moreo¬ver, the isolation is enhanced at the lower band by insert¬ing a metal strip which can cancel out original coupling. The inserted metal strip is the only additional decoupling structure in this design and has a simple texture with a compact size. The measured and simulated results reveal that the designed MIMO antenna can cover all the 2.4/5.2/5.8 GHz WLAN operating bands and within the recommended bands the isolations exceed by 20 dB

A comprehensive survey on 'circular polarized antennas' for existing and emerging wireless communication technologies

Circular polarized (CP) antennas are well suited for long-distance transmission attainment. In order to be adaptable for beyond 5G communication, a detailed and systematic investigation of their important conventional features is required for expected enhancements. The existing designs employing millimeter wave, microwave, and ultra-wideband (UWB) frequencies form the elementary platform for future studies. The 3.4-3.8 GHz frequency band has been identified as a worthy candidate for 5G communications because of spectrum availability. This band comes under UWB frequencies (3.1-10.6 GHz). In this survey, a review of CP antennas in the selected areas to improve the understanding of early-stage researchers specially experienced antenna designers has presented for the first time as best of our knowledge. Design implementations involving size, axial ratio, efficiency, and gain improvements are covered in detail. Besides that, various design approaches to realize CP antennas including (a) printed CP antennas based on parasitic or slotted elements, (b) dielectric resonator CP antennas, (c) reconfigurable CP antennas, (d) substrate integrated waveguide CP antennas, (e) fractal CP antennas, (f) hybrid techniques CP antennas, and (g) 3D printing CP antennas with single and multiple feeding structures have investigated and analyzed. The aim of this work is to provide necessary guidance for the selection of CP antenna geometries in terms of the required dimensions, available bandwidth, gain, and useful materials for the integration and realization in future communication systems

An Innovative Antenna Array with High Inter Element Isolation for Sub-6 GHz 5G MIMO Communication Systems

A novel technique is shown to improve the isolation between radiators in antenna arrays. The proposed technique suppresses the surface-wave propagation and reduces substrate loss thereby enhancing the overall performance of the array. This is achieved without affecting the antenna’s footprint. The proposed approach is demonstrated on a four-element array for 5G MIMO applications. Each radiating element in the array is constituted from a 3×3 matrix of interconnected resonant elements. The technique involves (i) incorporating matching stubs within the resonant elements, (ii) framing each of the four-radiating elements inside a dot-wall, and (iii) defecting the ground plane with dielectric slots that are aligned under the dot-walls. Results show that with the proposed approach the impedance bandwidth of the array is increased by 58.82% and the improvement in the average isolation between antennas #1&2, #1&3, #1&4 are 8 dB, 14 dB, 16 dB, and 13 dB, respectively. Moreover, improvement in the antenna gain is 4.2% and the total radiation efficiency is 23.53%. These results confirm the efficacy of the technique. The agreement between the simulated and measured results is excellent. Furthermore, the manufacture of the antenna array using the proposed approach is relatively straightforward and cost effective