In this paper, a 38 GHz 4-port multiple-input multiple-output (MIMO) antenna with considerable isolation and gain enhancement for 5G applications is introduced. The suggested antenna element is a monopole antenna composed of a circular patch with a rectangular slot etched from it and a partial ground plane is used to extend the desired frequency to operate from 36.6 GHz to 39.5 GHz with a center frequency of 38 GHz. The high isolation is achieved by arranging the four elements orthogonally and adding four stubs to reduce mutual coupling between elements at the desired frequency bands. The gain improvement is also introduced by placing a frequency selective structure (FSS) which is designed at the same frequency bands of the antenna under the suggested MIMO antenna to act as a reflector. The proposed four-element MIMO with the FSS prototype is built and tested in order to confirm the simulated results. The suggested antenna operated from 37.2 GHz to 39.2 GHz with an isolation of less than 25 dB across the obtained frequency range. The peak gain of the antenna is enhanced from 5.5 dBi to around 10 dBi by utilizing the FSS structure; furthermore, the back radiation is enhanced. The MIMO performance is validated by extracting its parameters and comparing with the simulated results. The results extracted from the simulation and the measurement show satisfactory matching along with the target band, indicating that the proposed structure could be used for 5G communications.

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).

This paper presents an application of new developed meta-heuristic Geometric Mean Optimization (GMO) algorithm, which mimics geometric mean operator unique features in mathematics with combination of power loss sensitivity index (PLSI) for the problem of optimal network reconfiguration (NR), optimal distributed generation (DG) unit allocation with optimal power factor (OPF) and unity power factor (UPF), simultaneous optimal NR and allocation of DG units with considering UPF and OPF, taking into account operational constraints and three loading levels (0.5 p.u loading (light load level), 1.0 p.u loading (nominal load level) 1.6 p.u loading (heavy load level) to solve single and multi-objective functions such as maximize voltage stability index (VSI), minimize total active power loss (TAPL) and voltage deviation (VD) in distribution network (DN). The effectiveness of the proposed technique has been evaluated on IEEE 33 bus and 69-bus networks. As a result of simultaneous optimal NR and DG unit allocation with OPF, substantial improvements have been observed in terms of VSI and minimization of TAPL and VD, as compared to optimal simultaneous NR and DG unit allocation with UPF, only DG unit allocation with UPF and OPF, and only NR and base case. When multiple objectives are considered, simultaneous allocation of NR and DG units with OPF provides better results for all types of load conditions. Using the results at nominal load level for the objective of TAPL, the proposed technique was compared with the results obtained with other existing algorithms in the literature to assess its efficacy. Based on the comparison of results, it is determined that the combined technique outperforms other techniques in the literature for the goal of TAPL at a nominal load level for all cases. This proposed technique process has a good accuracy and convergence speed which makes it a good choice for simultaneous optimal NR and DG unit allocation with UPF and OPF for problem-solving for all load conditions.

This work evaluates the performance of a triple-frequency operating circularly polarized wearable jute textile antenna in a human body sweat environment. The propounded antenna is designed to operate on the human body. So, contact with human skin allows the antenna to absorb the eccrine gland-rich mineral secretion (sweat) in regular use. The absorbed fluid alters the fabric substrate’s dielectric properties, ultimately leading to changes in the antenna performance. For that purpose, the antenna’s jute fabric is examined in a scanning electron microscope (SEM) and optical electron microscope to observe its water absorption characteristics in the wet state. An artificial sweat solution that closely mimics natural human sweat was taken in all the experimental conditions (The Pickering Laboratories’-Artificial Eccrine Perspiration). The present work addresses the antenna’s performance regarding operating frequencies, axial ratios, efficiency, and gains in three different sweat absorbency environments, i.e., exposure to light spray, partial exposure, and complete absorbency conditions. The antenna’s lifetime in the sweat environment was also inspected in an electrochemical workstation. The results from all these analyses confirm the robust functionality of the textile antenna in human sweat conditions.

This article describes a fractal-based MIMO antenna for 5G mm-wave mobile applications with micro-strip feeding. The proposed structure is a fractal-based spherical configuration that incorporates spherical slots of different iterations on the patch, as well as rectangular slots on the ground plane. These additions are meant to reduce patch isolation. The two-element MIMO antenna has closely spaced antenna elements that resonate at multiple frequencies, 9.5 GHz, 11.1 GHz, 13.4 GHz, 15.8 GHz, 21.1 GHz, and 26.6 GHz, in the frequency range of 8 to 28 GHz. The antenna’s broadest operational frequency range spans from 17.7 GHz to 28 GHz, encompassing a bandwidth of 10,300 MHz. Consequently, it is well-suited for utilization within the millimeter wave (mm wave) application, specifically for the 5G new radio frequency band n258, and partially covers some other bands X (8.9–9.9 GHz, 10.4–11.4 GHz), and Ku (13.1–13.7 GHz, 15.4–16.2 GHz). All the resonating bands have isolation levels below the acceptable range of (|S12| > −16 dB). The proposed antenna utilizes a FR4 material with dimension of 28.22 mm $\times$ 44 mm. An investigation is conducted to analyze the effectiveness of parameters of the antenna, including radiation pattern, surface current distributions and S parameters. Furthermore, an examination and assessment are conducted on the efficacy of the diversity system inside the multiple input multiple output (MIMO) framework. This evaluation encompasses the analysis of key performance metrics such as the envelope correlation coefficient (ECC), diversity gain (DG), and mean effective gain (MEG). All antenna characteristics are determined to be within a suitable range for this suggested MIMO arrangement. The antenna design underwent experimental validation and the simulated outcomes were subsequently verified.