In this paper, a 3.5 GHz microstrip patch antenna using three different substrates materials with varying relative permittivity have been designed. However, the thickness of the substrates are slightly different from each other which is 1.6 mm for FR-4, 1.575 mm for RT-5880 and 1.58 mm for TLC-30 have been chosen to carry out this work. The three substrates materials are FR-4 (Design-1), RT-5880 (Design-2), and TLC-30 (Design-3) with the relative permittivity of 4.3, 2.2, and 3, respectively. The antennas' performances in terms of reflection coefficient, voltage standing wave ratio (VSWR), bandwidth, gain, and efficiency performance is simulated, analyzed and compared using CST Microwave studio (CST 2019). The findings reveal that there is a significant change in gain and bandwidth due to different relative permittivity and the thickness value of the substrate materials. The gains achieved were at 3.338 dB, 4.660 dB, and 5.083 dB for Design-1, Design-2 and Design-3 respectively. The efficiency of the antennas also showed that TLC-30 gave the best efficiency at 75.70% when compared to FR-4 which was at 60.13% and RT-5880 which was at 61.51% efficiency. All the proposed antennas have a bandwidth above 100 MHz where Design-1 had a bandwidth of 247.1 MHz whilst Design-2 had a bandwidth of 129.7 MHz and finally, Design-3 had a bandwidth of 177.2 MHz.

The next-generation wireless technology that can fulfill such a demand, namely the fifthgeneration (5G) technology, should provide 1000 times larger capacity. Moreover, sixth-generation (6G) communication, which represents a significant upgrade from the fifth-generation (5G) network and is anticipated to operate from 100 GHz to 3 THz band, will be required in the years after 2030 due to newly developed data-hungry applications and the greatly expanded wireless network. To meet the ever-growing demands of wireless carriers, an efficient wireless access method that can improve wireless area throughput without expanding bandwidth or cell size is required. Radio Frequency (RF) Orbital Angular Momentum vortex waves (which is now on referred to as OAM waves) to address the concerns mentioned above have attracted much attention in recent years. Due to their orthogonality, different OAM waves of different modes can be multiplexed in the same frequency channel, which can greatly increase the channel capacity. Using the orthogonal modes, a new type of multiple access scheme known as Mode Domain Multiple Access (MDMA) can be used by multiple users using the same frequency channel without additional resources such as frequency and time. As a result, the channel capacity for the next generation wireless communication systems can be enhanced as well as the overall spectrum efficiency can be improved. This review paper begins with an overview of the next generation communication such as 5G communication technology and beyond. This paper first briefly discusses the theory of OAM waves and several methods to generate OAM waves. Various different designs have also been analyzed for their ability to generate OAM waves and discussion on several restrictions and solutions to resolve. Open concerns and development trends are discussed for possible future RF OAM antenna upgrades. This study also proposes that for next generation wireless communication employing OAM, the typically used Uniform Circular Array (UCA) could be paired with the Multiple-Input-Multiple-Output (MIMO) system to improve performance in dense or urban areas for multiusers. In addition, the purity of OAM-modes needs to be considered for efficient utilization of the OAM system for future communications at the radio domain.INDEX TERMS Orbital angular momentum (OAM) waves, uniform circular array antenna, 5G communication systems, antenna review paper, future wireless communication survey. I. INTRODUCTIONAdvances in mobile communications have significantly impacted economic and social growth over the past few decades. There have been noteworthy improvements with every generation of communication technology in terms of data rate, channel capacity, advanced applications such as video call, real-time health monitoring and so on. Based on the survey [1], it all started in the 1980s with the first generation (1G) technology, which mainly employed analog signals for voice services. The data rate was up to 2.4 Kbps.

This paper presents a novel microstrip patch antenna design using slots and parasitic strips to operate at the n77 (3.3–4.2 GHz)/n78 (3.3–3.8 GHz) band of sub-6 GHz and n96 (5.9–7.1 GHz) band of sub-7 GHz under 5G New Radio. The proposed antenna is simulated and fabricated using an FR-4 substrate with a relative permittivity of 4.3 and copper of 0.035 mm thickness for the ground and radiating planes. A conventional patch antenna with a slot is also designed and fabricated for comparison. A comprehensive analysis of both designs is carried out to prove the superiority of the proposed antenna over conventional dual-band patch antennas. The proposed antenna achieves a wider bandwidth of 160 MHz at 3.45 GHz and 220 MHz at 5.9 GHz, with gains of 3.83 dBi and 0.576 dBi, respectively, compared to the conventional patch antenna with gains of 2.83 dBi and 0.1 dBi at the two frequencies. Parametric studies are conducted to investigate the effect of the parasitic strip’s width and length on antenna performance. The results of this study have significant implications for the deployment of high-gain compact patch antennas for sub-6 GHz and sub-7 GHz 5G wireless communications and demonstrate the potential of the proposed design to enhance performance and efficiency in these frequency bands.

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In this paper, a compact microstrip patch antenna for 5G Millimeter wave technology has been proposed. By developing wide bandwidth characteristics, long ranges of data transfer are covered with better quality of signal transmission in 5G communication system. Modification of antenna element; patch width structured has influenced the frequency bandwidth. The design, analysis and optimization of the proposed work along with parametric analysis were performed using CST Microwave Studio. A microstrip patch antenna has been designed with high bandwidth millimeter wave, compact dimension, consistent radiation patterns and relatively higher gain at 28 GHz (mm-wave) band. FR-4 substrate has been employed in this work with a dielectric constant value of 4.3, thickness value of 1.6 mm and loss tangent value of 0.025.The proposed antenna has achieved high bandwidth which is 14.674 GHz with a reflection coefficient of -40.14 dB, Voltage Standing Wave Ratio (VSWR) value of 1.1098 dB and maximum gain of 5.29 dB with high directivity of 7.465 dBi. The antenna results of this work proved to be useful in fulfilling the requirements of wider bandwidth and higher gain particularly at 28 GHz for 5G applications.