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This research presents a high-performance MIMO antenna for 5G and next-generation wireless communication. Operating in the millimeter wave (mmWave) band, the antenna offers frequency and radiation pattern reconfigurability. A compact-size antenna, with dimensions of 22.5×30×0.787 mm3, exhibited peak gains of 7.5 and 6.5 dBi at 28 and 38 GHz, respectively. The envelope correlation coefficient (ECC) was improved through proper spacing and adopting a simple decoupling technique, ensuring efficient MIMO operation. Based on the evaluated reflection coefficients, bandwidths of 2.3 and 12.9 GHz at 28 and 38 GHz, respectively have been accomplished. The mutual coupling between antenna elements was minimized achieving improved isolation of −37 and −40 dB at the desired frequency bands. This corresponds to an envelope correlation coefficient and diversity gain of 1.6×10−4 and 9.99, respectively. The antenna gain was enhanced by incorporating a metasurface designed to optimize gain and improve isolation. For a single-element antenna, the gain was enhanced to 7.9 and 7.3 dBi at frequencies of 28 GHz, and 38 GHz, respectively. The antenna design incorporates frequency and pattern reconfigurability through switching selected antenna ports and patches. The proposed design's simplicity and antenna compactness make it practical for various mmWave communication systems. [ABSTRACT FROM AUTHOR]

This paper reports a design of 2×1 multiple input multiple output (MIMO) structure of antenna with 23×45 mm2 dimension. Each element in the MIMO antenna is a quarter wave transformer fed microstrip patch antenna. To lessen the effect of coupling, a rectangular parasitic decoupler is positioned between the two elements. Results report that antenna resonates at 6 GHz, coupling is reduced by 14 dB using parasitic decoupler S12 and S21 obtained with parasitic decoupler are same which -33.06 dB. The diversity gain (DG) is 9.99 dB, which is nearly close to 10 dB, and the envelope correlation coefficient (ECC) is less than 0.00034. These values reflect the good diversity performance. Measured findings match those from the simulation. As we confront the delicate environment, the proposed antenna is suited for number of wireless applications, including 802.11, 802.16 standards of IEEE. [ABSTRACT FROM AUTHOR]

In this paper, Index Modulation (IM) aided Generalized Space-Time Block Coding (GSTBC) is proposed, which intrinsically exploits the benefits of IM concept, diversity gain and spatial multiplexing gain. Specifically, the information bits are partitioned into U groups, with each being modulated by IM symbols (i.e. Spatial Modulation (SM), Quadrature SM (QSM),etc). Next, the structure of GSTBC is invoked for each K IM symbol, and a total of μ ​= ​U/K GSTBC codes are transmitted via T time slots. A Block Expectation Propagation (B-EP) detector is designed for the proposed IM-GSTBC structure. Moreover, the theoretical Average Bit Error Probability (ABEP) is derived for our IM-GSTBC system, which is confirmed by the simulation results and helpful for performance evaluation. Simulation results show that our proposed IM-GSTBC system is capable of striking an efficient trade-off between spatial multiplexing gain, spatial diversity gain as well as implementation cost imposed for both small-scale and large-scale MIMO antenna configurations.

This paper presents a novel, compact, and a dual-port MIMO antenna designed for ultrawideband, Sub-6 GHz, Industrial, Scientific, and Medical (ISM) band, and Internet of Things (IoT) applications. The antenna uses a stretchable jeans textile substrate embedded with elastomeric materials, enhancing its dielectric properties and flexibility. The innovation in this design stems from the introduction of defects (slots) on the stubs connected to a partially etched ground plane, which significantly improves isolation, achieving a port isolation of 47.5 dB which is superior to conventional designs. Operating across a wide frequency range of 2.82–14.23 GHz, it supports critical bands including WLAN, WiMAX, RAS, N79, C-band, and Sub-6 GHz, making it ideal for next-generation wireless systems. The antenna, with its compact footprint of 50 × 35 mm2, also covers ISM applications (2.4 GHz/5.8 GHz), making it versatile for medical and industrial communication needs. It delivers excellent performance, including a return loss (S11) below −10 dB, diversity gain above 9.95, and channel capacity loss below 0.25 bits/s/Hz. Additionally, it maintains a mean effective gain below 0.16 dB, an envelope correlation coefficient under 0.054, and a peak gain of 3.97 dB with over 82.45% radiation efficiency. These features make the proposed antenna a significant advancement, suited for future communication systems, wearable devices, and IoT-based Sub-6 GHz and ISM band applications. [ABSTRACT FROM AUTHOR]

The analysis of the 4 element MIMO configuration of a dual band CSRR loaded crescent slotted circular patch antenna is presented in this paper. The primary radiator of the proposed antenna is the logo of the author's institute. The design of primary radiator follows a fixed geometry, which includes the crescent slot, star shaped slots and a spline split. The undefined structures in the logo are the main challenge to obtain the desired resonance frequency. The CSRR etched at the ground plane of the antenna helps to attain the desired resonance at 2.15 GHz and 2.4 GHz. The 4 element MIMO configuration is proposed to serve the high data rate applications. When four similar antenna elements are placed on the single substrate, the CSRR provides high isolation too. To design the compact MIMO, the distance between the antenna elements is kept as minimum. Hence the distance between the antenna elements is maintained asλ/4 to mitigate the effects of multipath propagation as well as to minimize the interferences between the antenna elements. The complete antenna is designed on the FR4 substrate (εr = 4.4). The simulations are carried out using Ansys HFSS 2023 R2. The prototype of the designed antenna is developed and tested. The measured return loss is well below the 10 dB and the gain is 6.28 dB at 2.4 GHz resonance. The MIMO analysis of the antenna shows high isolation between the elements (<-13 dB), low envelope correlation co-efficient (0.00008) and high directive gain (> 9.995). The obtained results ensured that the proposed antenna is well suited for Wi-Fi, bluetooth and Zigbee applications. [ABSTRACT FROM AUTHOR]

This study introduces a novel, highly compact broadband millimeter-wave (mm-wave) antenna design and its Multiple-Input-Multiple-Output (MIMO) configuration proposed for 28 GHz applications targeting 5G networks. The antenna is designed over a 0.25 mm thick Rogers RT5880LZ substrate having a relative dielectric permittivity of 2 and an overall size of 16 mm × 16 mm. Its MIMO configuration utilizes polarization diversity and includes four elliptical-slot radiators integrated with microstrip-line structures, specifically optimized for 28 GHz operation. The performance of the proposed mm-wave MIMO configuration is validated through simulation of its S-parameters using CST software and measurements obtained with a vector network analyzer (VNA). The proposed antenna demonstrates excellent S-parameter performance, achieving a gain of up to 6 dBi and a radiation efficiency of 94% across the operational frequency band. Each antenna element exhibits an impressive wide operating bandwidth of 9 GHz, spanning from 22.2 to 31.4 GHz at a − 10 dB threshold. Evaluations of the MIMO system's performance indicate promising results, including an exceptionally low envelope correlation of about 10 - 5 and a diversity gain of around 10 dB throughout the operating bandwidth. The design also ensures significant isolation between MIMO elements without requiring decoupling structures. A physical prototype of the proposed antenna is fabricated and subjected to measurements, depicting a strong corelation between the measured and simulated data, with some minor variations attributed to fabrication tolerances and cable losses. Comparative analysis further emphasizes the potential viability of the proposed MIMO antenna positioning it as a viable candidate for future compact-sized mm-wave MIMO systems. [ABSTRACT FROM AUTHOR]

This investigation introduces a MIMO antenna using cylindrical shaped dielectric resonators and discusses both the design and implementation approaches. The proposed antenna design employs a CSRR structure and L-shaped metallic reflectors to improve isolation across many frequency bands. The typology operates at five different frequency ranges: 2.48, 3.92, 5.36, 7.4, and 8.56 GHz. It provides isolation levels of 39, 52.5, 33.8, 42.9, and 37.2 dB, respectively. The semi-circular tapered feed enables for circular polarization between 5.3 and 5.75 GHz. The simulated results indicate that the specified antenna is appropriate for usage in five frequency ranges: 2.1–2.6, 2.7–4.4, 4.9–5.8, 6.9–7.8, and 8.1–9.1 GHz. In a multiple-input multiple-output configuration, antenna performance is evaluated using a variety of diversity indicators, including the envelope correlation coefficient, mean effective gain, diversity gain, channel capacity loss, and total active reflection coefficient. Both simulations and measurements reveal that the proposed antenna can handle Wi-Fi 6, Wi-Max, and W-LAN services, including X-band. [ABSTRACT FROM AUTHOR]

A satellite communication signal suffers from attenuation due to rain, and this offers many problems for effective signal transfer and quality, thereby affecting satellite communication services needed for day-to-day activities. This study has adopted a fade mitigation technique called site and path diversity because it creates an effective pathway for signal availability at the receiver through the selection of a less attenuated signal. In this study, 30-min integration time Global Precipitation Mission satellite rain rate data was converted to 1-min integration time using a reliable conversion model. The Synthetic Storm Technique (SST) time series rain attenuation model was used to calculate the diversity gain through time series rain rate data for nine locations between 2008 and 2018, covering the Southwestern region of Nigeria, which is a typical tropical location. The usual wet and dry seasons in Nigeria were re-categorized into onset (Mid-March to April), intense (May–September), cessation (October to Mid-November), and dry (November ending to February) seasons. The results on seasonal rain attenuation based on SST showed that the intense and dry months exhibited the highest and lowest rain attenuation, respectively, at 0.01 percent of the time. The ITU-R models on site and path diversity were modified using the data generated from each of the locations to produce a suitable model for the region. The results showed an improvement in diversity gain when compared with the existing ITU-R and Hodge models based on the least RMSE produced. The overall results will assist in improving the quality of signals provided by the satellite communication system within the study locations, especially during heavy downpours. [ABSTRACT FROM AUTHOR]

A small MIMO antenna for use in dual bands is designed, simulated, and implemented in this work. Initially, a patch antenna was constructed and simulated, with further adjustments made to its size to achieve a dual-band performance at frequencies of 4.8 GHz and 6.8 GHz. A MIMO structure consisting of two elements is designedwith a partial ground plane. The electrical dimension of the antenna is 0.079λ × 0.0382λ at 4.8 GHz. The findings indicate that the MIMO antenna design demonstrated effective performance across intended frequency bands with 10 dB impedance bandwidth. The antenna displayed an essentially omnidirectional radiation pattern and achieved a satisfactory level of gain up to 5 dBi. The obtained findings exhibit promise, therefore establishing the suggested antenna as a viable option for 5G applications. The designed antenna is manufactured and practically tested in order to evaluate it's fundamental characteristics, including reflection coefficient and radiation pattern. These experimental findings were then compared to the outcomes obtained through simulation, resulting in a satisfactory consensus between simulated and measured results. [ABSTRACT FROM AUTHOR]

We propose an eight-element multiple-input multiple-output (MIMO) antenna array for 5G (fifth generation) New Radio (NR) applications in the n78 (3.3–3.8 GHz) band to achieve a high data rate. In the proposed work antenna elements have rectangular slots on the ground. Microstrip lines directly feed an open slot in this design. The dimensions of the open slot are 21.5 × 4 mm (0.24 λ × 0.046 λ at 3.5 GHz) and the slot covers 19.18% of the bandwidth in the frequency band 3.3–4 GHz. The eight antenna elements are arranged in such a way that they are coupled and also achieve an excellent degree of polarization. The proposed eight-element MIMO antenna array is fabricated and measured. Across the operation band, the measured isolation of the proposed antenna is −35 dB, −18 dB, −11 dB, −50 dB, −18 dB, −30db, −11 dB, and −35 dB for S12, S15, S26, S34, S53, S56, S64, and S78 respectively. The proposed antenna design can achieve desired antenna parameters, i.e. Isolation >11 dB, total efficiency >68%, and several MIMO performance characteristics are evaluated, including envelope correlation coefficient (ECC) < 0.03, the total active reflection coefficient (TARC) is −7 dB, the diversity gain (DG) is 9.96 dB and the channel capacity losses (CCL) is less than 0.02 were measured at desired bandwidth. The radiation pattern and antenna gain are also shown in this paper. The design is suitable for 5G communication networks. [ABSTRACT FROM AUTHOR]

This research work describes a compact four-port multiple input multiple output (MIMO) antenna using defective ground structure (DGS), and it perfectly supports the n77, n78, and n79 frequencies in 5G new radios (NR) bands. It can cover a wideband from 3.4 to 5.4 GHz with good impedance matching. The pair of antenna elements are orientated opposite to another pair with DGS. Due to this technique, it has minimal complexity, is less expensive, and improves isolation. It has also improved the frequency band's reflection coefficient and range using MIMO antenna with different stub lengths. Because it is less expensive, FR-4 substrate is used in the implementation of all antennas. Each antenna element has two identical stubs linked to the primary radiator. On the primary radiating element, a ''HI'' slot is created. The partial ground enhances impedance matching and radiation properties throughout the targeted band. The total dimensions of the four-port MIMO antenna are 46x30x1.6 mm³. The array elements' mutual coupling in the simulation is -14 dB. The ECC value is below 0.01, and the diversity gain (DG) is less than 10 dB. The suggested designs' measured gain ranges from 10 to 11.0 dB, and the radiation efficiency is nearly 91%. [ABSTRACT FROM AUTHOR]

This paper introduces a highperformance multiple - input - multiple - output (MIMO) antenna featuring a compact circular shape with slots, fed through co-planar wave-guide (CPW), emphasizing low mutual coupling. The proposed antenna has been physically realized using an FR4 substrate. Enhancing the antenna characteristics involved creating slits positioned at a 120-degree angle to each other, alongside a central circular-shaped slot within the patch. The arrangement of antenna elements involves an edge-to-edge distance of 0.18λ (4mm) to ensure isolation surpassing 15dB across the entire wideband range. The compact MIMO antenna overall dimension is 0.81λ x 1.45λ x 0.073λ (18 x 32 x 1.61 mm3). The CPW-fed circular patch MIMO antenna proposed in this study resonates at 12.611 GHz, and 13.852 GHz, exhibiting an impedance bandwidth of 2.65 GHz (12.116 GHz to 14.772 GHz). It showcases a reflection coefficient of -31.833dB and achieves an observed gain of 5.81 dBi. The observed results include a low envelope correlation coefficient (<0.025) and a high diversity gain (>9.87) at the resonating frequency. The measured outcomes closely align with the simulated results, indicating the efficacy of the designed wideband antenna. The designed wideband antenna is suitable for satellite downlink communications to transmit data at a higher rate. [ABSTRACT FROM AUTHOR]

This research presents a modified back reflector to increase isolation for a small ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna. The rectangular patch and narrow line strip on the bottom side of the substrate, arranged diagonally, make up this modified back reflector. The characteristic mode analysis provides a physical comprehension of the operating events that occur during the antenna’s evolution. The suggested antenna maintains an isolation level of more than 20.7 dB and has an operating bandwidth from 2.74 GHz to 14 GHz with a small dimension of 28.5 mm $\times 28.5$ mm $\times 1.6$ mm. Important factors that assess the effectiveness of the antenna are looked into, including radiation patterns, peak gain of 4.2 dB, radiation efficiency >85%, and MIMO diversity parameters. The suggested MIMO antenna is a feasible choice for UWB applications, as evidenced by the strong agreement between the measured and simulated results.

This paper presents a compact penta-band Multiple Input Multiple Output (MIMO) Dielectric Resonator Antenna (DRA). The proposed MIMO DRA consists of two rectangular DRs incorporating complementary split ring resonators (CSRRs) and an inverted T-shaped slot. The MIMO DRA achieves low impedance matching through simple microstrip feedlines, which is further enhanced by integrating a microstrip line with the DRA itself. Remarkably, the introduction of CSRRs enables the design to resonate at five distinct frequency bands, namely 2.8-GHz, 4.4-GHz, 5.8-GHz, 6.4-GHz, and 6.9-GHz. The simulated properties of the MIMO DRA were validated through over-the-air measurements performed on a fabricated prototype. The proposed MIMO design demonstrates impedance bandwidths of 2.09 %, 2.43 %, 2.17 %, 2.55 %, and 4.91 % at the above respective resonance frequencies. The proposed design exhibits exceptional stability in radiation pattern, featuring a noteworthy peak gain of 6.08 dBi and an efficiency of 91.35 %. Notably, the incorporation of an inverted T-shaped slot effectively enhances isolation between the MIMO elements, achieving a maximum diversity gain of 10 dB and an envelope correlation coefficient of 0.005 over 20-dB isolation. A good agreement between the simulation and measured results is obtained, which underscores the suitability of the CSRR-based MIMO DRA for multiband wireless applications (blue tooth, radio astronomy, remote sensing, WIFI, satellite television and 6G), making it a very valuable contribution to the field.

This study presents a novel, compact, diamond-shaped Multiple Input Multiple Output (MIMO) antenna system for 5G wireless communication. The proposed MIMO antenna system encompasses an array configuration, with each array unit comprising two antenna elements. The array elements are then orthogonally oriented making it a dual-port MIMO antenna system. The system is printed on a commercially available Rogers 5880, characterized by a permittivity ( $\varepsilon _{\mathrm {r}}$ ) of 2.2 and a loss tangent (tan( $\delta)$ ) of 0.0009. The overall dimensions of the MIMO antenna system are $26\times 16\times0.254$ mm3, operating in an mm-wave band with a frequency spectrum spanning from 26.2 to 34.2 GHz. The single antenna element exhibited a gain of 3.8 dBi and is then improved up to 7.6 dBi with two elements array arrangement. The system exhibited satisfactory MIMO characteristics with a maximum diversity gain of 10 dB, an envelope correlation coefficient of less than 0.0005, and an impressive 25 dB isolation between the antenna elements. Moreover, the proposed MIMO antenna array consistently maintained a radiation efficiency exceeding 90% across the entire desired frequency spectrum. Measurements were conducted with fabricated prototypes to validate the simulation results and were found in good agreement. The remarkable features of the proposed MIMO antenna system, such as compact size, wide bandwidth, good efficiency, and satisfactory gain values make it a promising candidate for 5G millimeter-wave wireless communication networks.

A two-stage adaptive non-orthogonal/orthogonal multiple access transmission scheme was designed for content delivery scenarios in wireless caching networks.For the scheme, a high-reliability user scheduling strategy was proposed, and the analytical expression of the outage probability and its asymptotic expression in high signal-to-noise ratio regime were derived by theoretical analysis.The analysis results indicate that the proposed strategy can achieve full spatial diversity gain.Simulation results demonstrate that compared with the instantaneous channel state information-based scheduling strategy, the random scheduling strategy, and the conventional orthogonal multiple access transmission strategy, the proposed strategy can achieve better content delivery reliability than existing strategies by obtaining the spatial diversity gain.

Recently, multiport multi-input and multi-output (MIMO) antenna technology has been the main focus of both manufacturers and researchers. So, their biggest challenge was to propose a small antenna that operates in broadband. We will be the primary contributors to the manufacturing process for this sort of antenna in this work, so we suggested a 4×4 MIMO antenna in a very compact size. As a result, the antenna dimensions are (W=16 mm, L=16 mm, H=1.6 mm) and it operates in millimeter bands ranging from 38 to 80 GHz, with a wide bandwidth of 42 GHz. This antenna was created using modern design principles, such as the Rubik’s cube form. According to the results, we noticed that the performance of the parameters is good, as the reflection coefficient is <10 dB for all frequencies. In addition, the isolation transmission performance between ports is <-26 dB, the envelope correlation coefficient (ECC) is <0.0000234 between all ports, and the diversity gain (DG) ranges between ports from 9.99 to 10 dB. Moreover, the percentage of the total antenna efficiency and radiation ranges from 70 to 98%, while the projected antenna gain range from 6.9 to 9.5 dB. With all these positive results, the suggested antenna has become one of the critical components in most contemporary wireless systems. [ABSTRACT FROM AUTHOR]

This manuscript presents a 50 Ω microstrip-fed quad-element high isolated ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with band-notched characteristics. The overall area of the proposed structure is 0.33 λ o × 0.33 λ o mm2 (where λ o depicts the free space wavelength corresponding to the lower cutoff frequency, i.e. 2.54 GHz), etched on an FR-4 substrate of thickness 0.8 mm. The top layer has four semicircular disc-shaped radiating elements that are identical and orthogonal to obtain better inter-element isolation and compactness. A reverse two-shaped slot is etched onto the radiating patches to attain a band-rejection capability. Moreover, a decoupling structure is also placed at the top layer to suppress the unwanted surface waves. The bottom layer consists of a ground plane, which is further modified with quasi-self complementary and meandered line slots. A rectangular slot is also etched below the feed line to better match the impedance near the lower cutoff frequencies. The simulated reflection coefficients (S 11) of the proposed antenna are less than −10 dB over 2.54 to 10.74 GHz frequencies except at 3.37 to 4.15 GHz (WiMAX/C band), and the simulated inter-port isolation (S 21) is greater than −15 dB over the entire UWB range of frequencies (3.1 to 10.6 GHz). Also, the measured S -parameter results well agreed with the simulated ones. Furthermore, the simulation study of the 20-element UWB-MIMO antenna is also investigated using the proposed quad-element structure. [ABSTRACT FROM AUTHOR]

This article presents a quad-element MIMO antenna designed for multiband operation. The prototype of the design is fabricated and utilizes a vector network analyzer (VNA-AV3672D) to measure the S-parameters. The proposed antenna is capable of operating across three broad frequency bands: 3–15.5 GHz, encompassing the C band (4–8 GHz), X band (8–12.4 GHz), and a significant portion of the Ku band (12.4–15.5 GHz). Additionally, it covers two mm-wave bands, specifically 26.4–34.3 GHz and 36.1–48.9 GHz, which corresponds to 86% of the Ka-band (27–40 GHz). To enhance its performance, the design incorporates a partial ground plane and a top patch featuring a dual-sided reverse 3-stage stair and a straight stick symmetrically placed at the bottom. The introduction of a defected ground structure (DGS) on the ground plane serves to provide a wideband response. The DGS on the ground plane plays a crucial role in improving the electromagnetic interaction between the grounding surface and the top patch, contributing to the wideband characteristics of the antenna. The dimensions of the proposed MIMO antenna are 31.7 mm × 31.7 mm × 1.6 mm. Furthermore, the article delves into the assessment of various performance metrics related to antenna diversity, such as ECC, DG, TARC, MEG, CCL, and channel capacity, with corresponding values of 0.11, 8.87 dB, −6.6 dB, ±3 dB, 0.32 bits/sec/Hz, and 18.44 bits/sec/Hz, respectively. Additionally, the equivalent circuit analysis of the MIMO system is explored in the article. It's worth noting that the measured results exhibit a strong level of agreement with the simulated results, indicating the reliability of the proposed design. The MIMO antenna's ability to exhibit multiband response, good diversity performance, and consistent channel capacity across various frequency bands renders it highly suitable for integration into multi-band wireless devices. The developed MIMO system should be applicable on n77/n78/n79 5G NR (3.3–5 GHz); WLAN (4.9–5.725 GHz); Wi-Fi (5.15–5.85 GHz); LTE5537.5 (5.15–5.925 GHz); WiMAX (5.25–5.85 GHz); WLAN (5.725–5.875 GHz); long-distance radio telecommunication (4–8 GHz; C-band); satellite, radar, space communications and terrestrial broadband (8–12 GHz; X-band); and various satellite communications (27–40 GHz; Ka-band). [ABSTRACT FROM AUTHOR]

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In order to improve the spectrum effectiveness, decrease the power consumption of wireless communication system, for a two-way cooperative non-orthogonal multiple access (NOMA) network with simultaneous wireless information and power transfer (SWIPT), an adaptive power splitting scheme of SWIPT was proposed.Based on the decode-and-forward protocol and the users’ distance information, the successive interference cancellation was carried out at the relay to decode the users’ messages and harvest the energy from the sources.An adaptive power splitting scheme was proposed based on users’ channel state information, which the relay could successfully decode the users’ information and harvest the most energy from the sources.Based on the harvested energy, the relay forwarded the decoded information of the users in the next time slot.According to the proposed adaptive power splitting scheme, the overall outage probability, end-to-end outage probability, and the diversity gain at high signal-to-noise ratio were derived.Compared with three-way cooperative orthogonal multiple access network with fixed power splitting of SWIPT, the proposed adaptive power splitting of SWIPT for two-way cooperative NOMA networks can achieve much better outage performance.

The demand for wireless communication in biomedical applications is increasing, thereby necessitating the development of reliable and efficient communication systems that can operate within the human body. This study introduces a novel dual-band two-port multiple-input multiple-output (MIMO) implantable antenna for deep tissue purposes with an overall size of $10.8\times 5.6\times0.254$ mm3 = 15.3 mm3. The proposed MIMO antenna operates in the 915 and 2450 MHz industrial scientific medical bands with a measured bandwidth of 82.5, 148.5 MHz (port 1) and 130, 89 MHz (port 2), in addition peak realized gains of −32.15 and −22.2 dBi, respectively, are observed. High-measured port isolation (over 20 dB and 30 dB at 915 and 2450 MHz bands, respectively) was accomplished by means of meandered resonators. The determined specific absorption rate was within the safe limits. The MIMO performance factors, for instance, the envelope correlation coefficient and diversity gain, were also evaluated and determined to be in the acceptable range. According to our knowledge, this is the first dual-band implantable MIMO antenna developed for biomedical applications. The results from the simulations and measurements indicate that the developed antenna holds great promise for enabling effective communication within the human body for biomedical applications.

A compact ultra-wideband Multiple-Input-Multiple Output (MIMO) Monopole antenna is proposed for frequency-notched applications. The proposed MIMO antenna consists of two identical Monopole antennas excited by two microstrip feeds. A stub is attached to the ground plane to improve isolation and impedance bandwidth. A quarter wavelength spur line is embedded on the feeding part of the antenna to achieve the notch frequency. The designed antenna exhibits −10 dB impedance bandwidth, covering the entire UWB spectrum. The L-shaped spur line contributes to the notch frequency at 5.5 GHz aiming to avoid interference from 5 to 6 GHz WLAN band. The planned model is fabricated and described in terms of impedance and radiation constraint measurements, compliant with those of results achieved from full wave simulation. [ABSTRACT FROM AUTHOR]

In this research article, a high-performance and compact 2-port slotted hexagonal structure multiple-input multiple-output (MIMO) system is presented. This structure is designed by using novel technology that includes the hexagonal structure with a slotted rotate C-shape structure for obtaining better isolation parameters and commercial 5G applications. The overall design size is 40 × 26 mm2, which is effectively miniaturized at a resonant frequency of 3.5 GHz for a lower sub-6 GHz. Moreover, dual-band characteristics are achieved in the hexagonal MIMO structure by embedding an inverted C-shape structure and monopole rectangular ground planes on the bottom sides of the patches. In addition, the hexagonal MIMO structure shows better diversity performance and high isolation in terms of the Total Active Reflection Coefficient, Envelope Correlation Coefficient, channel capacity loss, mean effective gain, and diversity gain. For the slotted hexagonal MIMO structures established, a better trade-off is achieved and it is found that the MIMO design is the best candidate for applications of wireless communication. [ABSTRACT FROM AUTHOR]

A wideband multiple-input multiple-output (MIMO) antenna for C-band applications is presented in this paper. It consists of 2 × 1 hexagonal motifs which serves as radiating elements. The side of each hexagonal element is 5.73 mm and the overall dimension of the proposed MIMO antenna is 30 × 20 × 1.6 mm3. The hexagonal motifs are embedded on inexpensive FR-4 lossy substrate. Thereafter, a circle with radius 1 mm is etched at the center of each hexagonal motif. Inverted L-shaped stubs are employed to attain efficient isolation between the nearby antenna elements. Four inverted L-shaped stubs are included to further enhance the isolation and eliminate the antenna size increment simultaneously, by suppressing the surface waves. Before using the decoupling approach, the MIMO antenna had an impedance bandwidth of 6.7 GHz and an isolation of −20 dB. The suggested antenna's impedance bandwidth and isolation are 5.83 GHz and −52 dB, respectively, after using a decoupling approach (inverted L-shaped stub). The proposed MIMO antenna had a peak gain and radiation efficiency of 3–7 dBi and better than 90% (with decoupling), 2.75 to 6 dBi and greater than 60% (without decoupling). To verify the proposed design, a prototype was developed to compare the simulated parameters with the measured one. The envelope correlation coefficient (ECC) was less than 0.05, and channel capacity loss (CCL) less than 0.3 was achieved with DGS. Besides, scattering matrix such as return loss S11 and transmission coefficient S21 between two elements, radiation pattern, and current distribution was also favorable. Thus, the proposed MIMO antenna is advantageous to be used for C-band applications such as developing new generation air-borne and space-borne radars, as well as X-band applications. [ABSTRACT FROM AUTHOR]

For the 5G applications of future sub-6 GHz a novel planar very low compact MIMO antenna is designed with improved isolation and impedance matching with T-shaped ground plane and mode analysis is presented here. A very low compact substrate with an area of 48 mm × 24 mm spiritual leaf shape radiating patches are situated in the same direction and maintained a separation distance of 2 mm. To improve the isolation and improved bandwidth, a remodeled structure of T-shaped grounded stub is placed among the pair of radiating antenna elements. The spiritual shaped antenna maintain a −10 dB required operating band of 2.43–3.01 GHz (580 MHz) and 3.19–3.84 GHz (650 MHz) with an isolation more than 20 dB maintained between antenna elements. The spiritual leaf shape antenna offers a radiation efficiency of 94.4 & 86.99% and its peak gain about 7.2 & 6.3 dBi. The simulated isolation is greater than 30 dB thought the dual-band with a maximum isolation of 54 dB. For this MIMO design diversity gain is around 10 dBi, channel capacity loss is less than 0.2 bits/s/Hz, group delay <1 ns and envelope correlation coefficient (ECC) which is lower than 0.0478. [ABSTRACT FROM AUTHOR]

In this paper, multiple-input multiple-output (MIMO) integrated radar and communications (IRC) system is studied, where the radar and communications parts work cooperatively, leading to a hybrid active-passive (HAP) MIMO radar and a radar-aided (RA) MIMO communications subsystems. To unify the performance metric for both subsystems, the diversity gain and multiplexing gain are derived for the RA MIMO communications and the HAP MIMO radar subsystems, based on which the tradeoff between the diversity and multiplexing gains is analyzed theoretically for each of the subsystems. The obtained diversity gain and multiplexing gain can facilitate the design and optimization of the IRC system. Employing these two unified performance metrics, the IRC system antenna number assignment is formulated as a multi-objective optimization problem, and the Pareto solutions are provided. The correctness of theoretical analysis is verified by simulations. Our results can provide useful guidance for system designers. • We present signals models for HAP MIMO radar and RA MIMO communications subsystems. • The diversity and multiplexing gains are derived for communications and radar subsystems. • The tradeoff between the diversity and multiplexing gains is analyzed theoretically. • Using these two unified metrics, the IRC system antenna number assignment is studied. [ABSTRACT FROM AUTHOR]

In this work, two elements and four elements compact UWB MIMO antennas are designed and fabricated. A printed circular disc with five circular slots is selected in this work due to its UWB performance and compact size for the MIMO antenna system. CST software is used in the simulation process. Measured S parameters show that the MIMO antennas work well from 3 GHz up to 20 GHz (maximum working frequency of the measurement instruments). The two elements MIMO antenna has a size of 70 × 40 mm2 meanwhile the four elements MIMO antenna has a size of 70 × 70 mm2. Measurement results show that the isolation among the antenna elements is higher than 20 dB. The envelope correlation coefficient, diversity gain, channel capacity loss, mean effective gain and total active reflection coefficient are studied in this paper. Simulations results show that the MIMO antennas have a satisfactory performance up to 50 GHz. [ABSTRACT FROM AUTHOR]

The outage performance of the cognitive relay networks is analyzed based on simultaneous wireless information and power transfer (SWIPT) and non-orthogonal multiple access (NOMA). The analytical expressions of overall outage probability and asymptotic expressions on high signal-to-noise ratio (SNR) are derived for the direct link transmission mode and the two-stage communication transmission mode. The analytical expressions are validated by Monte-Carlo simulations. The simulation results demonstrate that the outage performance is improved by through the direct link transmission. Furthermore, compared with the conventional cognitive relay networks with orthogonal multiple access (OMA), superior outage performance and high energy efficiency are achieved for the cognitive relay networks based on SWIPT-NOMA. [ABSTRACT FROM AUTHOR]

The outage performance of the cognitive relay networks is analyzed based on simultaneous wireless information and power transfer (SWIPT) and non-orthogonal multiple access (NOMA). The analytical expressions of overall outage probability and asymptotic expressions on high signal-to-noise ratio (SNR) are derived for the direct link transmission mode and the two-stage communication transmission mode. The analytical expressions are validated by Monte-Carlo simulations. The simulation results demonstrate that the outage performance is improved by through the direct link transmission. Furthermore, compared with the conventional cognitive relay networks with orthogonal multiple access (OMA), superior outage performance and high energy efficiency are achieved for the cognitive relay networks based on SWIPT-NOMA. [ABSTRACT FROM AUTHOR]

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