Multiple-input multiple-output (MIMO) technology has emerged as a highly promising solution for wireless communication, offering an opportunity to overcome the limitations of traffic capacity in high-speed broadband wireless network access. By utilizing multiple antennas at both the transmitting and receiving ends, the MIMO system enhances the efficiency and performance of wireless communication systems. This manuscript specifies a comprehensive review of MIMO antenna design approaches for fifth generation (5G) and beyond. With an introductory glimpse of cellular generation and the frequency spectrum for 5G, profound key enabling technologies for 5G mobile communication are presented. A detailed analysis of MIMO performance parameters in terms of envelope correlation coefficient (ECC), total active reflection coefficient (TARC), mean effective gain (MEG), and isolation is presented along with the advantages of MIMO technology over conventional SISO systems. MIMO is characterized and the performance is compared based on wideband/ultra-wideband, multiband/reconfigurable, circular polarized wideband/circular polarized ultra-wideband/circular polarized multiband, and reconfigurable categories. The design approaches of MIMO antennas for various 5G bands are discussed. It is subsequently enriched with the detailed studies of wideband (WB)/ultra-wideband (UWB), multiband, and circular polarized MIMO antennas with different design techniques. A good MIMO antenna system should be well decoupled among different ports to enhance its performance, and hence isolation among different ports is a crucial factor in designing high-performance MIMO antennas. A summary of design approaches with improved isolation is presented. The manuscript summarizes the various MIMO antenna design aspects for NR FR-1 (new radio frequency range) and NR FR-2, which will benefit researchers in the field of 5G and forthcoming cellular generations.

This review provides a comprehensive analysis of the design, materials, fabrication techniques, and applications of flexible wearable antennas, with a primary focus on their roles in Wireless Body Area Networks (WBANs) and healthcare technologies. Wearable antennas are increasingly vital for applications that require seamless integration with the human body while maintaining optimal performance under deformation and environmental stress. Return loss, gain, bandwidth, efficiency, and the SAR are some of the most important parameters that define the performance of an antenna. Their interactions with human tissues are also studied in greater detail. Such studies are essential to ensure that wearable and body-centric communication systems perform optimally, remain safe, and are in compliance with regulatory standards. Advanced materials, including textiles, polymers, and conductive composites, are analyzed for their electromagnetic properties and mechanical resilience. This study also explores innovative fabrication techniques, such as inkjet printing, screen printing, and embroidery, which enable scalable and cost-effective production. Additionally, solutions for SAR optimization, including the use of metamaterials, electromagnetic band gap (EBG) structures, and frequency-selective surfaces (FSSs), are discussed. This review highlights the transformative potential of wearable antennas in healthcare, the IoT, and next-generation communication systems, emphasizing their adaptability for real-time monitoring and advanced wireless technologies, such as 5G and 6G. The integration of energy harvesting, biocompatible materials, and sustainable manufacturing processes is identified as a future direction, paving the way for wearable antennas to become integral to the evolution of smart healthcare and connected systems.

The demand for broad-band antennas has been increased in the recent years. They find to be extensively used in high frequency and high speed data communication. The factors affecting the bandwidth of the microstrip antenna is discussed in this paper. There are two main parameter responsible for the broadening of the antenna. One is the height of the dielectric substrate and another one is the width of the patch. In this paper, we study the performance characteristics of rectangular patch antenna with variable thickness of the substrate and width of the patch. One of the parameter is varied keeping the other fixed and the characteristic effects on resonant frequency, band width and gain are studied.

This research paper presents a simple design consideration of Ultra-Wide Band (UWB) Microstrip antenna using a centrally loaded rectangular slot. An analytical study of the effects of different size and shapes of slots on the performance characteristic of UWB Microstrip antenna is presented. Insertion of slot and the changes in dimension of ground plane has a high impact on the behavior and parameter of the patch antenna. To improve the bandwidth of the patch antenna, proper insertion of slot on the planer patch structure has been used. In the paper 12mm by 15.6 mm rectangular patch antenna carved on FR4 substrate is presented. Both the simulated and the measured result show the operation of the antenna in the entire UWB range. This parametric study would be of a great interest in the designing of compact antennas for wireless communications operating in UWB.

While targeting the sixth generation (6G) wireless communication which incorporates mainly the Internet of Things (IoT), the Internet of Vehicles (IoV) becomes a vital component to be implemented. A vehicular antenna is designed by using the modified design of the Vivaldi antenna that can cover all the frequency bands for the long-term evolution (LTE) and the mid-band fifth-generation (5G) wireless systems (ranging from 3.3 GHz to 6.5 GHz). The proposed design is optimized by analyzing the effect of the variation in the dimensions of the antenna, changing the position of the taper, the rectangular slot dimensions and the diameter of the circular slot etc. The presented automotive antenna operates at four frequency bands ranging from 3.62 GHz - 4.03 GHz (410 MHz), 4.17 GHz–5.38 GHz (1210 MHz), 5.57 GHz–6.16 GHz (590 MHz) and from 6.23 GHz - 6.64 GHz (410 MHz) with the minimum reflection coefficient of -39 dB, -39.06 dB, -50.42 dB and -12.45 dB, respectively. The proposed antenna offers the high gain of 7.6 dB, 6.7 dB, 9.3 dB and 7.4 dB for the four bands of the operating spectrum, respectively. The analysis of the reflection and radiation characteristics of the antenna when placed on the vehicle confirms the suitability of an antenna for the smart vehicle to vehicle communications.

In this article, the compact wideband elliptically slotted semi-circular patch radiator with the defected ground structure for sub-6 GHz applications is designed and developed. The proposed miniaturized patch radiator offers flexibility in adjusting the band of operation by varying the slot dimensions. The effective size reduction is achieved by comparing different iterations in the process of designing and the size of the regular circular-shaped radiator is reduced into the semi-circular radiating patch. The impact of the variation of effective radius of the semi-circular patch, major-axis radius of the elliptical slot, ground plane length, and feed line width is investigated. The size of the proposed radiator is 23.885 × 23.885 × 1.405 mm³. This compact structure manifests the wide bandwidth of 2140 MHz (3.2 GHz–5.34 GHz) with 50% of fractional bandwidth (FBW). The measured results show good agreement with the simulated results. The various parameters validate the utility of the radiator in the C band of super-high frequency (SHF) spectrum and n77 (3.3 GHz–4.2 GHz), n78 (3.3 GHz–3.8 GHz), and n79 (4.4 GHz–5 GHz) bands of the frequency range 1 (FR1) of the sub-6 GHz 5G spectrum.