Limited Size MIMO Antenna Systems and Mutual Coupling Challenge

Author(s):  
Nassrin Elamin ◽  
Tharek Rahman

The wireless communication high data rate is achievable by installing more than one antenna in receiver and transmitter terminals as MIMO antenna. In order to obtain the MIMO gain (Envelope Correlation Coefficient (ECC) = 0.5), the antenna elements must be at least separated by a distance of 0.5? (? is the operating wavelength of 0.7~3.8 GHz which is the frequency range of most of the current wireless communication applications). This value is big relative to limited sizes devices. A practical MIMO antenna should have a low signal correlation between the antenna elements and good matching features for input impedance. Moreover, MIMO system performance can be improved by reducing mutual coupling between closely spaced antenna elements. Miniature high isolated MIMO antenna system has been presented in this chapter; also many MIMO antenna systems were analyzed and categorized based on the implemented isolation techniques. Furthermore several MIMO antenna evaluation methods have been discussed.

2014 ◽  
Vol 8 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Mohammed Younus Talha ◽  
Kamili Jagadeesh Babu ◽  
Rabah W. Aldhaheri

A novel compact multiple-input–multiple-output (MIMO) antenna system operating from 5 to 7.3 GHz is proposed for wireless applications. It comprises of two similar antennas with microstrip feeding and radiating patches developed on a reduced ground plane. The developed antenna system resonates at a dual-band of 5.4 and 6.8 GHz frequencies, giving an impedance bandwidth of 38% (based on S11 < −10 dB). The unique structure of the proposed MIMO system gives a reduced mutual coupling of −27 dB at 5.4 GHz resonant frequency and −19 dB at 6.8 GHz resonant frequency and in the entire operating band the coupling is maintained well below −16 dB. The envelope correlation coefficient of the proposed MIMO system is calculated and is found to be less than 0.05 in the operating band. The measured and simulation results are found in good agreement.


Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Praveen Vummadisetty Naidu ◽  
Sai haranadh Akkapanthula ◽  
Maheshbabu Dhanekula ◽  
Neelima Vummadisetty ◽  
Arvind Kumar

Abstract This article discusses a 4-port micro-strip fed MIMO Antenna system with a triangular slot and an inverted L shape strip has been designed and analysed for both 2.3 GHz WiBro and Ultra-wide-band applications. The suggested antenna has been etched on a cost-effective epoxy (FR-4) substrate having ϵ r ${{\epsilon}}_{r}$  = 4.4 with an overall dimension of 45 × 45 × 1.6 mm3. Mutual coupling of −18 dB between the radiators has been obtained by orthogonal placement of radiators. From the simulated and practical results, the proposed compact MIMO system operates in frequency bands 2.26–2.42 GHz and 3.7–10.8 GHz respectively. The proposed small triangular MIMO system operates with an ECC less than 0.005 with an acceptable channel capacity loss <0.5 bits/s/Hz. Further, the diversity characteristics like DG, MEG, TARC, and group delay have been calculated and are presented in this paper.


2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Raghad Ghalib Saadallah Alsultan ◽  
Gölge Ögücü Yetkin

E-shaped multiple-input-multiple-output (MIMO) microstrip antenna systems operating in WLAN and WiMAX bands (between 5 and 7.5 GHz) are proposed with enhanced isolation features. The systems are comprised of two antennas that are placed parallel and orthogonal to each other, respectively. According to the simulation results, the operating frequency of the MIMO antenna system is 6.3 GHz, and mutual coupling is below −18 dB in a parallel arrangement, whereas they are 6.4 GHz and −25 dB, respectively, in the orthogonal arrangement. The 2 × 3 matrix of C-shaped resonator (CSR) is proposed and placed between the antenna elements over the substrate, to reduce the mutual coupling and enhance the isolation between the antennas. More than 30 dB isolation between the array elements is achieved at the resonant frequency for both of the configurations. The essential parameters of the MIMO array such as mutual coupling, surface current distribution, envelop correlation coefficient (ECC), diversity gain (DG), and the total efficiency have been simulated to verify the reliability and the validity of the MIMO system in both parallel and orthogonal configurations. The experimental results are also provided and compared for the mutual coupling with simulated results. An adequate match between the measured and simulated results is achieved.


Author(s):  
Eva Rajo-Iglesias ◽  
Mohammad S. Sharawi

Multiple-Input-Multiple-Output (MIMO) technology has appeared to overcome the data throughput limit faced by conventional Single-Input-Single-Output (SISO) wireless communication systems. In MIMO, a significant increase in the data throughput is obtained using multiple data streams sent and received by multiple antenna elements on the transmitter and receiver ends, and this is why fourth generation (4G) wireless systems are supporting more real time multimedia applications and videos compared to older generations. The design of MIMO antenna systems is not a trivial task, and needs careful design practices. Several performance metrics have been identified for MIMO antenna systems that need to be evaluated on top of the conventional single element antenna systems. In this chapter, we will start by giving a brief background on wireless systems evolution and then highlighting the advantages of MIMO technology and its use in current 4G and future 5G wireless communication standards. The second section will treat in detail the various performance metrics that are needed to evaluate the behavior of a MIMO antenna system. The new metrics that are required for MIMO performance characterization such as the total active reflection coefficient (TARC) for multi-port antenna systems, correlation coefficient, diversity gain and channel capacity evaluation will be discussed in details. Several examples of single-band and Multi-band MIMO antenna systems are considered next with various types of antenna elements and covering a variety of wireless applications and device sizes. The chapter ends with a discussion on some of the challenges encountered in the design of MIMO antennas.


2019 ◽  
Vol 9 (11) ◽  
pp. 2371 ◽  
Author(s):  
Fatima Amin ◽  
Rashid Saleem ◽  
Tayyab Shabbir ◽  
Sabih ur Rehman ◽  
Muhammad Bilal ◽  
...  

This research work proposes a compact four-port multiple-input multiple-output (MIMO) antenna that operates in the whole license free ultra-wideband (UWB) spectrum of 3.1–10.6 GHz. Spatial diversity has been introduced by arranging these antennas in close proximity without developing a strong mutual coupling. Antenna elements are evolved from a conventional rectangular patch antenna whereas a customized decoupling structure is introduced on the back side of the substrate to achieve the desired isolation level. The parasitic decoupling structure consists of different features which are resonant at different frequencies offering a whole UWB coverage. In addition to the decoupling structure a dumbbell shaped stub has also been introduced to the partial ground plane to suppress the mutual coupling. The overall measured isolation among elements is more than 20 dB. Different MIMO performance parameters have also been investigated from the measured results. Whole MIMO system measures 0.41 λo × 0.44 λo at 3.1 GHz. The MIMO system is intended for high data rate and short-range communication devices used in wireless personal area networks.


2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Vladimir Ssorin ◽  
Alexey Artemenko ◽  
Alexander Maltsev ◽  
Alexey Sevastyanov ◽  
Roman Maslennikov

This paper considers design of microstrip MIMO antennas for an LTE/WiMAX USB dongle operating in the 2.5–2.7 GHz frequency band. The MIMO system includes two antenna elements with an additional requirement of high isolation between them that is especially difficult to realize due to size limitations of a USB dongle. Three approaches to achieve the needed system characteristics using microstrip PCB antennas are proposed. For the first design, high port-to-port isolation is achieved by using a decoupling techniques based on a direct connection of the antenna elements. For the second approach, high port-to-port isolation of the MIMO antenna system is realized by a lumped decorrelation capacitance between antenna elements feeding points. The third proposed antenna system does not use any special techniques, and high port-to-port isolation is achieved by using only the properties of a developed printed inverted-F antenna element. The designed MIMO antenna systems have the return loss S11and the insertion loss S21bandwidths of more than 200 MHz at the −8 dB level with the correlation coefficient lower than 0.1 and exhibit pattern diversity when different antenna elements are excited. Experimental measurements of the fabricated antenna systems proved the characteristics obtained from electromagnetic simulation.


2019 ◽  
Vol 11 (4) ◽  
pp. 413-419 ◽  
Author(s):  
Ziyu Xu ◽  
Qisheng Zhang ◽  
Linyan Guo

AbstractA printed multiband Multi-Input Multiple-Output (MIMO) antenna is proposed in this paper. This MIMO antenna system comprises two symmetric printed monopole antennas. Each antenna element consists of multiple bend lines, producing four resonant modes and covering the GSM900, PCS, LTE2300, and 5G bands. Simulated and measured results prove that the proposed MIMO antenna can be applied to traditional 2G, 3G, 4G, and present 5G mobile communication. By etching four inverted L-shaped grooves on its ground plate, mutual coupling between the adjacent antenna elements has been suppressed. This makes the |S21| at all four resonant modes is lower than −40 dB. In addition, its low coupling mechanism has been analyzed by surface current distribution. The designed multiband MIMO antenna provides an idea of reference to realize low mutual coupling between antenna elements, which is also realizable in infrared or optical regimes with appropriate designs.


2019 ◽  
Vol 8 (1) ◽  
pp. 75-81
Author(s):  
N. Al Shalaby ◽  
S. G. El-Sherbiny

In this paper, A multiple input Multiple Output (MIMO) antenna using two Square Dielectric Resonators (SDRs) is introduced. The mutual coupling between the two SDRAs is reduced using two different methods; the first method is based on splitting a spiral slot in the ground plane, then filling the slot with dielectric material, "E.=2.2". The second method is based on inserting a copper parasitic element, having the same shape of the splitted Spiral, between the two SDRAs.  The effect of replacing the copper parasitic element with Carbon nanotubes (CNTs) parasitic element "SOC12 doped long-MWCNT BP" is also studied. The antenna system is designed to operate at 6 GHz. The analysis and simulations are carried out using finite element method (FEM). The defected ground plane method gives a maximum isolation of l8dB at element spacing of 30mm (0.6λo), whereas the parasitic element method gives a maximum isolation of 42.5dB at the same element spacing.


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