Contents I. Introduction
In this present age of the fourth industrial revolution, a significant contribution is played by the wireless communication system in every aspect of life [1]. The communication world is facing a new dimension of challenge due to the rapid increase in the number of users of the internet, mobile phone, laptop, computer, tablet or any other IoT devices. Therefore, the existing 2G, 3G and 4G commendation systems are being overly crowded which is pressing the researchers to explore new technology for meeting up the demand of high speed data communication network [2]–[6]. The allotted 5G frequency spectrums lie from sub-6 GHz to mm-wave band though the 5G frequency range varies from country to country. The spectrum of 3.4 GHz–3.6 GHz has been declared as sub-6 GHz band during world radio communication conference 2015 [7] and the spectrum of 3.4 GHz-3.8 GHz by Ofcom (a regulator for the communications services, United Kingdom) [8]–[10]. In order to mitigate the demand of ultra high data rate requirements for future massive wireless communications, the communication world is transforming from 4G to 5G by using comparatively higher frequencies to reach wider bandwidth [11]–[13]. Microstrip patch antennas are getting attention from researchers for the deployment of sub-6 GHz wireless devices because of its flexibility, less weight, compact size, simplicity and cost effectiveness [7] [10]. The antenna researches tune the antenna to intended frequency band applications by modifying the shape of patch such as circular, rectangular, triangular, square, hexagonal shape etc [14], actually it can be any shape, applying different types of slots, using different types of ring resonator, PID diode, via, dielectric resonator, parasitic elements, etching multiple substrate and superstrate, metamaterial, tuning different types of feeding techniques. In order to make the antenna suitable for the target application, there is a hundred percent freedom of the antenna designers choosing the shape of patch and slots as well as the other different strategies including feeding techniques [15].
