In this study, a compact dual band 2-element Multiple Input Multiple Output (MIMO) multiband antenna is designed. Two radiating patches make up the suggested antenna, which aims to produce multiband resonance antenna. The 45×33 mm2 two element MIMO antenna is printed on a 1.6 mm thick FR-4 substrate with a dielectric constant of ɛr = 4.3 and a loss tangent of 0.02. An optimized dual band antenna was produced as a result of a parametric research based on the FDTD technique, which improved the structure's performance with regard to operational bandwidth. Additionally, a separate 50Ω-fed two-element MIMO arrangement is taken into consideration. By introducing spatial diversity into the MIMO arrangement, good isolation can be achieved without the need to use well-known techniques of decoupling structures. Results shows that the system has a mutual coupling of less than -15 dB between the various elements and operates on two bands: "3.5GHz WiMAX." and "4.2 GHz " Moreover, an analysis of the Diversity Gain (DG), Envelope Correlation Coefficient (ECC) and Channel Capacity Loss (CCL) parameters shows that they satisfy the practical standards: DG > 9.80, ECC < 0.06, and CCL < 0.4 bits/s/Hz over the relevant bands

In this study, a compact (30 × 30 × 0.508 mm3) 8-port MIMO antenna for unmanned aerial vehicles (UAV), vehicle-to-everything (V2X) and 5G applications is designed, developed, tested and discussed. After a systematic study, an optimal single element of the proposed antenna is chosen from four steps (Step 1, Step 2, Step 3, Step 4). The geometry of the proposed antenna comprises eight circular radiating elements on the top plane of the substrate in which pentagon structure is etched out from each element to resonate it at 5.5 GHz. Stepped rectangular structure is removed from the ground plane underneath of each radiating elements. A dielectric substrate (RT/Duorid (5870 tm)) is used to fabricate the proposed antenna design with following specification: εr = 2.33, h = 0.508 mm, loss tangent (tan δ = 0.0012). A unique structure of the proposed antenna geometry exhibits −10 dB wideband bandwidth of 1.32 GHz (5–6.32 GHz) and high isolation (> 30 dB) in entire band. A peak gain of 6.5 dB and 92% radiation efficiency have been achieved. Moreover, good degree of MIMO characteristics such as envelope correlation coefficient (ECC) (< 0.001), diversity gain (DG) (> 9.87 dB), channel capacity loss (CCL) (< 0.04 bits/s/Hz), channel capacity (37.6 bits/s/Hz) and mean effective gain (MEG) (−12 dB < MEG < −3 dB) have also been obtained. The antenna design was simulated through HFSS and fabricated & tested for further validation of results. Simulated results were found in strong concordance of experimental results.

The MIMO antenna design is specifically engineered to support optimized performance in emerging 6G networks. Utilizing advanced techniques such as metamaterials and machine learning algorithms, the antenna system achieves high data rates, improved diversity, and robust signal reliability, making it ideal for next-generation ultra-fast and intelligent wireless communication technologies. Our advanced metamaterial configuration demonstrates high gain and bandwidth. A low ECC value 0.0004 shows minimal correlation, ensuring better signal diversity and improved system performance. Similarly, a high diversity gain confirms the antenna’s efficiency in maintaining robust signal reception under varying conditions. The CCL values of 0.0916 bits/Hz bits/Hz provide insight into the information-carrying capacity of the MIMO configuration. The MIMO antenna design achieves a maximum gain of 8.9 dBi and a wide bandwidth of 30 THz. This performance is attained through a combination of parametric optimization and machine learning techniques, enhancing both efficiency and operational range. The machine learning algorithms used for optimization yield a high R² value of 0.99, indicating excellent prediction accuracy. The proposed antenna, featuring metamaterial characteristics, demonstrates strong potential for next-generation 6G networks, offering enhanced performance, efficiency, and compact design integration.

Due to the high mobility, flexibility, and low cost, unmanned aerial vehicles (UAVs) can provide an efficient way for provisioning data communication and computing offloading services for massive Internet of Things (IoT) devices, especially in remote areas with limited infrastructure. However, current transmission schemes for unmanned aerial vehicle-assisted Internet of Things (UAV-IoT) predominantly employ polling scheduling, thus not fully exploiting the potential multiuser diversity gains offered by a vast number of IoT nodes. Furthermore, conventional opportunistic scheduling (OS) or opportunistic beamforming techniques are predominantly designed for downlink transmission scenarios. When applied directly to uplink IoT data transmission, these methods can incur excessive uplink training overhead. To address these issues, this paper first proposes a low-overhead multi-UAV uplink OS framework based on channel reciprocity. To avoid explicit massive uplink channel estimation, two scheduling criteria are designed: minimum downlink interference (MDI) and the maximum downlink signal-to-interference-plus-noise ratio (MD-SINR). Second, for a dual-UAV deployment scenario over Rayleigh block fading channels, we derive closed-form expressions for both the average sum rate and the asymptotic sum rate based on the MDI criterion. A degrees-of-freedom (DoF) analysis demonstrates that when the number of sensors, K, scales as ρα, the system can achieve a total of 2α DoF, where α∈0,1 is the user-scaling factor and ρ is the transmitted signal-to-noise ratio (SNR). Third, for a three-UAV deployment scenario, the Gamma distribution is employed to approximate the uplink interference, thereby yielding a tractable expression for the average sum rate. Simulations confirm the accuracy of the performance analysis for both dual- and three-UAV deployments. The normalized error between theoretical and simulation results falls below 1% for K &gt; 30. Furthermore, the impact of fading severity on the system’s sum rate and DoF performance is systematically evaluated via simulations under Nakagami-m fading channels. The results indicate that more severe fading (a smaller m) yields greater multiuser diversity gain. Both the theoretical and simulation results consistently show that within the medium-to-high SNR regime, the dual-UAV deployment outperforms both the single-UAV and three-UAV schemes in both Rayleigh and Nakagami-m channels. This study provides a theoretical foundation for the adaptive deployment and scheduling design of UAV-assisted IoT uplink systems under various fading environments.

Abstract Abstract—In this paper, dual-port electric-inductive-interdigital capacitor (ELIDC) metamaterial Array multi-input-multi-output (MIMO) antenna is designed with enhanced gain, bandwidth, and isolation for frequency bands 5.125GHz – 5.825GHz and 5.925GHz-7.125GHz for the Wi-Fi 5 and 6E applications. The proposed MIMO antenna comprises of dual-port corporate fed ELIDC metamaterial arrays, which are fed orthogonal to each other with footprint of (1.14λ × 1.22λ) on FR-4 Dielectric substrate. The ground plane consists of a Defected Ground Structure (DGS) for enhancement of bandwidth. A novel four split-ring resonator (SRR) array is embedded between two radiating elements of the DGS ground plane to increase the isolation. The isolation is enhanced to -30dB by incorporating the SRR array. To validate the blocking characteristics of electromagnetic propagation between antenna elements, metamaterial constitutive parameters in the desired resonance frequency is extracted using the nicolson-ross-weir (NRW) method. The proposed antenna design equations are verified using a full wave simulator and the proposed MIMO antenna is simplified into an equivalent circuit model. The proposed ELIDC array MIMO antenna is fabricated and measured, S parameters, gain and radiation pattern are giving good consistency with simulated results. The envelope correlation coefficient (ECC), diversity gain (DG), and total active reflection coefficient (TARC) of the diversity performance show that the proposed ELIDC array MIMO antenna can be used in MIMO Tx/Rx systems.

Abstract An advanced isolation control technique is proposed for a terahertz (THz) multi-input multi-output (MIMO) antenna, significantly enhancing port-to-port isolation. This approach utilizes a silicon-based dielectric resonator antenna for high-performance tunable THz MIMO system. The design follows a structured evolutionary process, beginning with a dual-feed (DF) configuration without a dielectric resonator as the baseline model. Enhancements were introduced by incorporating a graphene metal coating, improving tunability and isolation. Further refinements involved integrating a split square ring resonator without an RDRA, enhancing isolation and polarization characteristics. The design was then optimized by introducing a metal-coated RDRA, improving gain, radiation efficiency, and circular polarization purity. Additionally, a complementary split ring resonator-loaded circularly polarized DF structure was incorporated for further performance enhancement. The proposed MIMO antenna achieves 25.5 dB isolation at 7.2 THz without a metal coating. By applying a graphene coating, isolation increases to 49 dB at 7.42 THz, using graphene’s tunable conductivity under an external DC bias for dynamic reconfiguration. The antenna exhibits excellent pattern diversity, with an envelope correlation coefficient below 0.003 and a diversity gain of 9.94 dB. Further isolation improvement is achieved by integrating a split-ring resonator on the dielectric material, enhancing isolation up to 59 dB. These advancements make the proposed antenna highly suitable for THz applications.

This paper presents a compact magneto-electric dipole (MED) antenna optimized for wideband circularly polarized (CP) radiation for 5G applications. It incorporates a staircase-shaped electric dipole with trimmed corners to excite orthogonal modes for enhanced CP performance. The proposed single-layer MED antenna achieves a wide-impedance bandwidth ( dB, – GHz) and CP bandwidth ( dB, – GHz) with a compact footprint of . There is a symmetrical radiation pattern with a co-to-cross polarization ratio dB and a stable gain of dBi. An equivalent circuit model is optimized via particle swarm optimization (PSO). The optimized MED antenna is utilized to investigate various CP-MIMO configurations and wideband sequential arrays. Next, a CP-MIMO antenna system is developed, employing polarization diversity in parallel and mirror configurations. Isolation is improved by etching a ground slot between the MED elements, yielding isolation levels of below dB and dB, respectively. Further, a CP-MIMO configuration is designed and evaluated. This arrangement demonstrates an envelope correlation coefficient (ECC) of and a diversity gain of approximately 10 dB across the operating bandwidth. Finally, a sequential array is designed that applies a sequential rotation and phase excitation to MED elements for high-gain CP 5G communications. Here, various array sizes are evaluated, with an MED array providing CP radiation ( dB) from 20 to 30 GHz with enhanced impedance and axial ratio bandwidths and stable gain with a peak value of dBi.

This paper introduces a design methodology for a multiple-input multiple-output (MIMO) antenna that achieves multi-port operation, high gain, as well as compact dimensions. The proposed design employs two dual-polarized radiators integrated with two hybrid couplers. This architecture enables a four-port MIMO array to be realized using only two radiating elements. Meanwhile, the hybrid couplers simultaneously excite both ports of the dual-polarized elements with equal magnitude and a phase difference, facilitating high-gain radiation. To validate the proposed concept, an antenna prototype was fabricated and tested. Measurements confirm that the antenna, with an overall compact size of × × , achieves a 3.1% operating bandwidth (4.72-4.87 GHz) with inter-port isolation better than 10 dB. Within this band, the antenna maintains a measured gain of around 8.0 dBi. Additionally, the antenna also performs good diversity performance in terms of Envelop Correlation Coefficient, Diversity Gain, Channel Capacity Loss, and Mean Effective Gain.

With the emergence of every new generation of wireless communication, 6G will require ultra-high-speed, low-latency, and high-spectrum efficiency techniques, which would need sophisticated antenna designs working on the terahertz (THz) spectrum range. This article introduces a miniaturized 2-element MIMO microstrip antenna with the graphene radiation patch on a polyimide substrate and copper ground for the THz regime. The proposed antenna exhibits a resonant frequency at 4.78THz with the ultra-low return loss of − 52dB and has an operation bandwidth of 3.81–5.13THz, which achieves a wide bandwidth of 1.32THz in totality. The proposed antenna has a maximum gain of 11.97dB, high radiation efficiency reaching as high as about 90%, and a good isolation (− 40dB) is achieved between ports. The diversity gain (DG) and the envelope correlation coefficient (ECC) are 9.999 and 0.0000175, which confirms that the diversity performance is a good candidate for future-generation high data rate systems. An equivalent RLC circuit is proposed and verified by full-wave simulations in order to describe the impedance behavior of the antenna accurately. Moreover, ML regression algorithms such as Extra Trees Regression are incorporated in the design flow, which efficiently reduces the evaluation time and allows multi-parameter optimization. Comparative studies also verify that the proposed antenna outperforms existing antennas in terms of bandwidth, gain, isolation, and flexibility and is therefore a potential candidate for 6G communication, biomedical imaging, and high-resolution sensing. The proposed antenna, which exhibits compact size, superior isolation, and high efficiency, yields tremendous potential for 6G applications at high Data Rate and presents a strong candidate to operate in the next generation of wireless communication devices.

Sonar, so good: Tree-reefs drive net gain in fish size, abundance, and diversity

Abstract This paper presents a novel MIMO antenna configuration that utilizes cylindrical dielectric resonator antennas (CDRAs) integrated with substrate integrated waveguide (SIW) technology, tailored for wideband operation within the terahertz (THz) frequency range. A Defective Ground Structure (DGS) was incorporated into the two-port SIW-MIMO CDRA framework to achieve an enhanced bandwidth performance. Circular polarization (CP) is obtained across the desired frequency bands. The incorporation of a graphene layer on the CDRA surface alters the resonant behavior, resulting in a noticeable shift in the antenna’s operating frequencies. The antenna exhibits two separate wideband responses, achieving an impedance bandwidth of 1.51 THz from 4.6 to 6.11 THz and 2.05 THz across the 7.71 to 9.76 THz spectrum. Isolation exceeding ≤ –25 dB is consistently sustained over the operational bandwidth. Moreover, the antenna supports dual-band circular polarization, offering 3 dB axial ratio bandwidths (ARBWs) of 23.23% between (4.68–5.85 THz) and 15.56% between (8.02–9.50 THz). A peak gain of 6.02 dB is recorded, along with a high radiation efficiency of 78.26%. By modifying the feed lengths, the polarization characteristics can be effectively tuned, rendering the design adaptable for diverse THz applications. The antenna’s MIMO capabilities are validated through essential diversity performance indicators, including an Envelope Correlation Coefficient (ECC) below 0.01, a Channel Capacity Loss (CCL) under 0.5 bps Hz −1 , a Mean Effective Gain (MEG) of –3 dB or better, a Diversity Gain (DG) close to 10 dB, and a Total Active Reflection Coefficient (TARC) of less than –10 dB. Additionally, the application of a graphene coating plays a significant role in expanding the impedance bandwidth while enhancing both frequency agility and axial ratio tunability.

Abstract The work proposes a low-profile, wideband circularly polarized (CP) dual-element Multiple-Input-Multiple-Output (MIMO) antenna design for C-band and selected 3GPP FR1 5G NR bands. The designed two-element MIMO antenna utilizes a planar patch configuration and achieves high isolation by strategically incorporating an optimized rectangular-shaped slot in the ground plane of the antenna, which acts as a decoupling structure, eliminating the need for any external complex structure. The two MIMO elements are placed with an optimized decoupling slot of 7 mm width to reduce mutual coupling between them. The performance of the proposed CP-MIMO antenna has been validated comprehensively through both full-wave simulations and experimental measurements. The antenna demonstrates a measured -10 dB impedance bandwidth of 3.81 GHz (4.24 - 8.05 GHz) and a 3-dB axial ratio bandwidth (ARBW) of 2.7 GHz (4.36 - 7.06 GHz), validating CP performance. The key MIMO parameters investigated include Total Active Reflection Coefficient (TARC &lt; -10 dB), Envelope Correlation Coefficient (ECC &lt; 0.005), Diversity Gain (DG ≈ 9.98), and Channel Capacity Loss (CCL ≈ 0.35 bits/s/Hz), confirming its excellent diversity standards. The proposed CP MIMO antenna occupies a compact footprint of 49 x 24 x 1.6 mm³, with better inter-element isolation of more than 20 dB across most of the operating band, a peak gain of 5.7 dB, high simulated efficiency of 96%, and polarization agility. Furthermore, the scalability of the design has been comprehensively demonstrated by extending it to 3-port and 4-port MIMO configurations, supported by detailed simulation results. These results validate its suitability for integration into next-generation wireless communication systems.

THz antennas, which function at high speeds, frequencies, and data rates, were developed in response to the increased need for high-speed communication equipment. In this work, a MIMO antenna operating between 2.25 and 2.85 THz is built and optimised with partial ground. The designed antenna possesses H-shaped slots and circular rings over the patch to enhance the antenna performance. The proposed antenna states the isolation loss value of 50 dB across the operating frequency with a bandwidth of 0.6 THz. In the manuscript, two antennas were designed, the first one having only circular slots and the second one, in addition to the circular slots over the patch, also including H-slots. The antenna has the highest gain value of 8.9 dBi in the design. Optimising the design is performed using parametric optimisation and geometrical parameters. The suggested antenna measures 50 x 50 x 100 µm². The suggested antenna can be used for high-speed communications because of its high gain and operating frequency applicability. Antenna having a low Error Correlation Coefficient (ECC) value of 0.08, a high Diversity Gain (DG) value with minimum mutual coupling < -25dB, an optimum Total Active Reflection Coefficient (TARC) value of -55dB and a Mean Effective Gain (MEG) value of 8.5dB. These antennae also operate across biomedical imaging applications, wireless network applications, beam scanning applications, and satellite communication applications with reflection coefficient values < -25dB.This study supports UN SDG 9: Industry, Innovation and Infrastructure by advancing sustainable THz communication technologies, and contributes to SDG 3: Good Health and Well-Being through its biomedical imaging applications.

The compact and wideband patch antennas applied to WiFi 7 multiple-input multiple-output (MIMO) antenna systems are presented. The MIMO antenna structure consists of four multi-branch radiating patches fed by coupled microstrip lines, which occupies a size of . By exploiting multiple resonant modes, an impedance bandwidth of 37% (5.07–7.37 GHz) achieves a reflection coefficient of less than −10 dB and fully encompasses both WiFi 7 high-frequency ranges. To alleviate mutual coupling, two decoupling structures, named complementary split-ring resonators (CSRRs), are employed between the MIMO elements to interact with the undesirable surface current; furthermore, the proposed orthogonal placement of four elements further minimizes radiation coupling. Consequently, the proposed array achieves measured isolations greater than 14.5 dB and 11 dB at 5 GHz and 6 GHz bands, respectively. The prototype of the proposed MIMO antenna has been manufactured. It has also been measured and the results show similarity with the simulations. The measured radiation pattern and the diversity performance, including the envelope correlation coefficient (ECC), diversity gain (DG), and multiplexing efficiency, are calculated, and they verify the outstanding diversity characteristics of the proposed MIMO antenna. This makes it a promising solution for emerging WiFi 7 wideband applications.

This paper presents a miniaturized (13x13x0.8 mm3) quad-port MIMO antenna for 5G NR n257, n258, & n261 for mm-wave usage. The recommended antenna designed at 29 GHz chose an optimal design (Stage 3) after a careful examination of performance at numerous stages. The single radiating plane consists of an inverted L-shaped design with identical hexagonal slotted loaded DGS. The quad components of the MIMO antenna are set orthogonally for best inter-element mutual coupling. The key feature of the recommended design is (a) impedance bandwidth of 25 -29.5 GHz (Simulated) and 25 to 27.5 GHz or 28 to 29 (measured), along with outstanding mutual coupling of > 25 dB suitable for new radio frequency (RF) bands n257, n258, & n261 (b) an impressive peak gain of 9.5 dB at a full band. Diversity parameters, such as the envelope correlation coefficient (ECC), diversity gain (DG), TARC and channel capacity loss (CCL) are analyzed and calculated the performance characteristics of the proposed MIMO antenna. The suggested antenna's findings have been confirmed by experimental data and have been shown to be in close proximity to the simulated results.

In this paper, an eight-port millimeter-wave multiple-input-multiple-output (MIMO) antenna array operating at 28 GHz for vehicle to vehicle (V2V) communication is designed and developed. It consists of eight 2 × 2 half-mode substrate integrated waveguide (HMSIW) antenna arrays placed along the edges of a regular octagon. The 2 × 2 HMSIW antenna array is fed through a corporate feeding network that comprises of two-stage in-phase T-junction power divider. The designed antenna array has an overall volume of 0.72 {lambda }_{0}^{3}, where λ0 is the free-space wavelength at operating frequency of 28 GHz. It exhibits excellent peak realized gain (> 12.2 dBi) and high inter-port isolations (> 30 dB) among all the antenna elements without usage of any decoupling network. The MIMO performance of the proposed MIMO antenna array is evaluated in terms of envelope correlation coefficient (ECC) and diversity gain (DG). The performance parameters lie within their acceptable limits. The link budget analysis of the proposed MIMO antenna array is performed with the evaluation of path losses and link margins. To further enhance the gain and radiation characteristics, the 8-port MIMO antenna design, originally based on a 2 × 2 array, is extended to a 4 × 4 array configuration. High gain, high inter-port isolation and excellent radiation characteristics make the designed millimeter-wave MIMO antenna array a potential candidate for V2V communication system.

This paper presents a computational intelligence-optimized multiband MIMO antenna for next-generation laptops, addressing the demand for compact, high-performance, and multiband wireless connectivity. The proposed 4-port MIMO configuration, with an overall footprint of 94.1 × 28.29 × 0.8 mm3, is optimized for seamless integration along the laptop’s top edge, where minimal width is crucial. It supports operation at 2.45 GHz, 5 GHz, and 6 GHz, enabling compatibility with dual and tri-band Wi-Fi 6E routers. To accelerate the design process and reduce manual iteration, machine learning (ML) algorithms including AdaBoost, SVM, CatBoost, and Decision Trees were employed. A simulation dataset was generated in CST studio by systematically varying critical antenna parameters. This dataset was used to train the ML models, enabling them to learn the nonlinear relationships between geometry and performance metrics such as S-parameters, gain, efficiency, envelope correlation coefficient (ECC), diversity gain. Upon training, the models predicted optimal design parameters for desired performance goals. The resulting antenna exhibited isolation greater than 16 dB, ECC below 0.08, and a measured realized gains of 0.73, 2.1, and 3 dBi across the operating bands. In addition, the channel capacity loss remained under 0.35 bits/s/Hz, confirming strong MIMO performance. This work highlights that incorporating computational intelligence into antenna design not only expedites the development process but also improves system efficiency, providing a scalable and intelligent solution for next-generation multifunctional, high-speed laptop platforms.

This research introduces a meticulously designed dual-port antenna tailored to operate within the 2.3-2.4 GHz frequency spectrum. The design specifically addresses challenges of achieving high isolation, reducing envelope correlation, and maintaining robust diversity performance in compact multi-antenna systems. The configuration prioritizes optimal performance metrics to meet stringent communication demands. Notably, the isolation between antenna elements surpasses 20 dB, ensuring minimal interference and enhanced signal integrity in diverse communication environments. Achieving impressive radiation performance, the antenna promises robust signal transmission capabilities while adhering to strict power consumption constraints. Its exceptionally low ECC of less than 0.1 contributes to heightened data reliability, crucial in modern communication systems. Moreover, the antenna exhibits a remarkable diversity gain, nearing 10 dB, facilitating improved signal reception and effectively combating fading and multipath propagation. Notably, its measured channel capacity of 8 bps/Hz underscores its potential for high-bandwidth applications. Fabrication and measurement outcomes meticulously align with theoretical projections, confirming successful synchronization between the antenna's designed specifications and real-world performance, validating its practical viability for diverse wireless communication systems.

The design and analysis of a quad-terminal graphene–ceramic radiator functioning in the THz domain are presented in this study. The hybrid mode (HEM 11 δ ) inside the silicon ceramic is stimulated by means of an asymmetrical fan-formed slot. This slot shape creates the circular field in between 3.5 and 4.1 GHz. A metasurface (MS) suspended over a two-terminal radiator enhances the gain within the working regime, i.e., 11.0 dBi. The polarization and space diversity concept improves terminal-to-terminal isolation above 30 dB. As confirmed by CST electromagnetic simulations, the radiator can function throughout 3.25–4.15 THz. Frequency tunability is provided by the graphene covering on the dielectric. The antenna’s diversity gain (DG) is around 9.9 dB, and its envelope correlation coefficient (ECC) is less than 0.01. The suggested MIMO radiator is a viable option for THz-enabled 6G wireless communication systems because of its high gain and steady far-field performance.

Exploiting polarization isolation for high diversity gain in a THz MIMO system