Compact MIMO Antenna Array for 5G Applications

Multi-input multi-output (MIMO) systems are pivotal for modern wireless communication, offering enhanced data rates and efficient spectrum utilization. However, compact designs in wireless terminals often lead to closely spaced antennas, causing significant electromagnetic (EM) coupling that degrades performance. This report introduces a novel self-decoupled antenna design to mitigate mutual coupling in compact MIMO systems. The design adds two stubs to the widely used Inverted-F Antenna (IFA) to minimize EM interactions between antennas. These additional elements increase the isolation from 10 dB to over 20 dB, reducing inter-port interference, while antenna efficiency improves from 68% to 81.43%, ensuring stronger signals and reduced energy loss. The lower envelope correlation coefficient (ECC) shows enhanced data throughput and system capacity. The design eliminates external decoupling structures, reducing cost and complexity while maintaining a compact form factor. This distinctive design provides a cost-effective, high-performance solution for compact MIMO systems, particularly in 5G applications.

<p>A compact microstrip fed printed monopole MIMO antenna with ultrawideband (UWB) frequency response (S11< -10 dB for 3.1-10.6 GHz) is proposed in this paper. The proposed antenna is miniaturized and has a high isolation of > 23 dB between the ports compared to the existing UWB multiinput multi output (MIMO) antennas in the literature. The proposed antenna is built on FR4 substrate with thickness of 1.6 mm using all-digital single chip architecture and it is planar in geometry to be easily integrated with the other electronic components in the printed circuit board (PCB). The UWBMIMO antenna is analyzed using simulation and measurements and its performance is investigated. The antenna is extremely useful for low power short range communications and it provides high multipath immunity due to diversity.</p>

This work discusses the concept, simulation, and experimental validation of a compact ultra-wideband (UWB) fractal-based multi-input multi-output (MIMO) antenna. MIMO antenna is fabricated on an FR-4 layer for current wireless connectivity uses. The proposed antenna is formed by four elliptical radiating elements, each incorporating an identical elliptical notch organized in a rotating orthogonal orientation. A U-slot with a cross-shaped modified ground structure is introduced to enhance isolation and impedance resembling. The fractal MIMO antenna occupies a tiny size of 0.5λ × 0.5λ × 0.016λ (at 3.1 GHz) and operates over an extensive spectrum that spans from 3 GHz to 24 GHz, which makes it appropriate for various wireless technologies. The measured and simulated findings show outstanding performance throughout the operational bandwidth, with a return loss at several resonance points < -10 dB, apart from the notch frequency. To ensure optimal MIMO functioning, the suggested configuration generates a diversity gain surpassing 9.98, a minimal envelope correlation coefficient (ECC < 0.004), and high isolation ( ≤ − 21 dB). The antenna’s gain exceeding 2 dBi further validates its appropriateness for contemporary portable networks of communication, including satellite communications, radar, 5G, and the Internet of Things. The promising fractal MIMO antenna’s ability to achieve small dimensions, broad performance, and better isolation is confirmed by the high agreement between modelling and experimental findings.

A compact four-port multi-input, multi-output (MIMO) antenna with good isolation is proposed for sub-6 GHz and Internet of Things (IoT) applications. Four similar L-shaped antennae are placed orthogonally at 7.6 mm distance from the corner of the FR4 substrate. The wideband characteristics and the required frequency band are achieved through the L-shaped structure and with proper placement of the slots on the substrate. To obtain good isolation between the ports, rectangular slots are etched in the bottom layer and are interconnected. The proposed antenna has total dimensions of 40 mm × 40 mm × 1.6 mm. The interconnected ground plane provides good isolation of less than -17 dB between the ports, and the impedance bandwidth obtained by the proposed four-port antenna is about 54% between the frequency range of 3.2 GHz to 5.6 GHz, thus providing a wideband antenna characteristic covering sub-6 GHz 5G bands (from 3.4 to 3.6 GHz and 4.8 to 5 GHz) and the WLAN band (5.2 GHz). The proposed design antenna is fabricated and tested. Good experimental results are achieved when compared with the simulation results. As the proposed design is compact and low profile, this antenna could be a suitable candidate for 5G and IoT devices.

This research work present a P cut multi input multi output (MIMO) patch antenna with the parasitic element. Due to this importance MIMO antenna famous day by day, in the thesis work discuss the MIMO antenna based research work and its different properties. The main problem of MIMO antenna is mutual computing, low gain, less directivity and ECC. These are major problems with MIMO antenna. The size of MIMO P cut patch antenna is 48 × 48 × 32 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> with rectangular parasitic element size is 46 × 48 × 32 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in which 1mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> slot. For better performance and bandwidth improvement use half ground. The resultant of P cut MIMO patch antenna shows reduction in mutual coupling (MC) and improvement of Envelope Correlation Coefficient (ECC). For design and simulation of presented MIMO antenna use computer simulation technology (CST) software, 2016 version. The outcome of designed MIMO antenna compare with different presented work shown in this research article in result section. The presented MIMO antenna cover different frequency range that cover wireless communication application ranges IEEE 802.11n and Wi-Max.

In this paper, a novel and computationally e-cient algorithm which combines Array Signal Processing (ASP) approach with Fourier Optics (FO) is developed in the realm of gain enhancement achieved by placing Uniplanar Compact-Photonic Band Gap (UC- PBG) structures on top of microstrip antennas. The proposed scheme applies FO to the well-known sampling theorem borrowed from Digital Signal Processing (DSP) analysis in the framework of ASP approach which we refer to as the FDA algorithm. The FDA algorithm is suitable for lossless UC-PBG structures with 1- D, 2-D and 3-D lattice of canonical geometrical apertures, such as circular, octagonal, hexagonal, and square. In order to validate the proposed approach, two difierent UC-PBG structures of octagonal and circular apertures are considered at 2.6GHz. The UC-PBG structures under consideration consist of two layers positioned above a microstrip antenna; each layer is an array of 9 £ 9 apertures separated by half of the focal length distance of the lens in the near- fleld of the microstrip antenna. The performance of the microstrip antenna with and without the UC-PBG is reported using numerical simulations performed using CST Microwave Studio (CST MWS) based on the Finite Integration Technique (FIT). The radiation patterns and directivity of the microstrip antenna based on UC- PBG structures are evaluated using the proposed FDA algorithm and

A dual band and compact multi input multi output (MIMO) antenna for WLAN has been present in this letter. The proposed antenna operates over a wide frequency range of 1.93–2.79 GHz and 4.79–6.19 GHz suitable for long-term evolution (LTE) and wireless local area network (WLAN). The two elements antenna with a compact size of 39×40×1.5 mm3 which is designed on a FR4 substrate with a dielectric constant of 4.4. The simulated results show a bandwidth of 860MHz (low-frequency) and 1400 MHz (high-frequency). The maximum gain for each operation element is 2.11dBi. The proposed MIMO antenna can be used in wireless communication system.

The increasing saturation of microwave frequencies poses challenges for modern networks, making terahertz (THz) communication a promising solution for higher data rates, provided energy-efficient devices are developed. This study presents an innovative quad port multi-input multi-output (MIMO) antenna for sixth-generation (6G) terahertz wireless communications applications. The single-element radiator featuring a patch of modified elliptical quadrant shape in the presence of a C-shaped ground plane is conceptualized at an initial stage. Furthermore, two and four elements-based MIMO structures are constructed by placing the conceptualized single antenna elements. Additionally, the proposed configuration of the quad-element MIMO antenna comprises a plus-shaped isolation structure with a circular ring on a low-cost, transparent polyimide substrate. This innovative design enhances multi-resonance behavior, optimizes impedance matching, and achieves miniaturization while maintaining high isolation. The antenna operates across five distinct frequency bands: 0.97–1.27, 3.37–3.9, 8.68–9.17, 11.02–11.79, and 13.36–13.80 THz, with fractional bandwidths (FBW) of 26.79%, 14.59%, 5.49%, 6.75%, and 3.24%, respectively. It achieves a peak gain of 8.09 dBi and a radiation efficiency exceeding 82%. The antenna demonstrates exceptionally low mutual coupling (<30 dB) between adjacent elements along with attractive MIMO metrics, offering a low ECC of 0.0001, DG close to 10, a TARC of less than -10 dB, and a CCL of 0.4 bps/Hz. These results confirm the antenna's potential as an effective solution for THz MIMO systems, positioning it as a strong candidate for next-generation 6G wireless communications utilizing terahertz spectrum.

A very fast and efficient method for designing compact antenna arrays preserving the maximum channel capacity of multi input multi output (MIMO) systems using infinitesimal dipole model (IDM) theory is presented. Using this method each antenna element is replaced by a set of infinitesimal dipoles producing the same electric fields of the antenna. The recently introduced Invasive weed optimization (IWO) algorithm is employed to find the infinitesimal dipole models. The algorithm is applied to a planar inverted F-antenna designed as an element of a compact array for MIMO applications. Using the obtained IDMs, self and mutual admittances between the antennas are predicted. Therefore, correlation coefficients of the MIMO array system are achieved using S-parameters. Having the correlation of the system, the location and orientation of each antenna are optimized to find the minimum correlation value for the MIMO antenna system. Using the optimization technique, very low cross correlation coefficient is obtained for very close antennas over a finite ground plane.

This article describes the effect of antenna envelope correlation in the throughput of multi‐input multioutput (MIMO) antenna system.Despite the fact that antenna envelope correlation is a critical factor that determines the data transmitting capability of a MIMO antenna system, an appropriate level of envelope correlation for MIMO antennas in mobile communication devices has never been proposed yet. In this article, we have examined various MIMO antenna systems designed with different correlation values to provide a guideline for industrial WiMAX MIMO applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26158

This letter presents a simple and compact dual-polarized linear antenna array characterizing high interport isolation for in-band full-duplex communications. By using the symmetrically shared-interface configuration integrated with a 180° hybrid, the self-interference resulting from the impedance mismatching between the antenna and feeding network and the coupling among the antenna elements can be well suppressed theoretically. Furthermore, to achieve the high isolation in practice among a wide frequency band, a slotline-based 180° hybrid is proposed and studied, which features a high isolation between the sum and differential ports. For further verification, a demonstrator of a 1 × 4 array centered at 5.0 GHz is developed and fabricated. The measurements denote that the shared −10 dB impedance bandwidth of the two ports is from 4.75 to 5.18 GHz, and the interport 50 dB isolation bandwidth is from 4.55 to 5.66 GHz (over 21.7%).

A method of analyzing and/or improving printed circuit antenna performance by the addition of a superstrate (cover) layer has recently been discussed for the case of a Hertzian dipole [1]. In this paper, the characteristics of rectangularly shaped microstrip antennas involving a superstrate are investigated using the method of moments. Results for center fed microstrip dipoles as well as microstrip antennas excited by electromagnetic coupling from a microstrip transmission line are presented. Mutual coupling is also discussed and the effect of the superstrate layer on microstrip antenna parameters is analyzed.

A novel technique for reducing the electromagnetic coupling between closely spaced MIMO antenna arrays on a compact ground plane is presented. The proposed ground plane introduces pairs of miniaturised convoluted slits between two PIFAs resulting in a significant reduction of the mutual coupling within their operating frequency band. The proposed slits have a small footprint and are positioned close to the edges of the ground plane thereby occupying very little space. Different configurations of the PIFAs are studied and results obtained in 3D electromagnetic simulation software (CST Microwave studio) are presented.

This chapter introduces some principles and methods for designing modal test plans based on finite element method (FEM) results. The number of points in FEM is closed, generally in the thousands. From the FEM results, many orders of modal frequencies and vibration shapes can be obtained. However, in a modal test, only the foremost orders are concerned; thus, the number of measured points is limited, generally in the tens. There are 2–4 exciting points for a multi input multi output (MIMO) test, whereas 1 exciting point is practical for a single input single output (SIMO) test when the modes are not closed. When the number of foremost orders and measured points are fixed, it is not practical to automatically compute the position of the total measured points from the FEM results for several reasons. First, the computing work is very complex and time-consuming. Second, for the best mathematical results, some key points may be lost and some points that cannot be measured are included. Most importantly, none of these point are able to construct a regular plane, so the result is unacceptable aesthetically. The practical approach is to design an initial plan in which the position is measured manually according to common experience and the space is evenly distributed. By computing the maximum value of the un-diagonal elements of the modal assurance criterion (MAC) matrix and observing the modal shape animation of the simplified results, some measured positions can be modified. If some points need to be deleted in the initial base, this task can be completed automatically by dividing all measured positions into two groups: points that are allowed to be deleted and points that cannot be deleted. After the positions of all measurements are fixed, the number of exciting points and their positions can be obtained automatically according to the exciting energy distribution of different orders in each position.

In this letter, we propose and experimentally validate a compact hybrid-fed microstrip antenna for the harmonics-based radar and sensor systems, which receive the fundamental tone and retransmit the modulated second harmonic. The proposed microstrip antenna is based on a simple single-layered and dual-feed structure, consisting of an inner circular patch operating in the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> mode (second harmonic; 6 GHz) and an outer split-ring patch operating in the higher order TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub> or TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">310</sub> mode (fundamental frequency; 3 GHz). By varying the feed position and the geometry of the split-ring patch, a specific higher order mode can be excited at the fundamental frequency. Moreover, analytical expressions were derived for calculating the antenna's resonant frequencies. Our measurement results show that the maximum realized gain is 1.17 dB at 3 GHz and is 3.33 dB at 6 GHz, with good impedance matching (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -15 dB) and high isolation (<; -20 dB).