In 21st century graphene has termed as one of the significant material in wireless communication due to amazing electrical and optical properties . According to Edholm’s law, wireless data rates tend to be doubled in eighteen months . Higher channel capacity is required for the next generation communication system which demands the exploitation of higher frequency band for data transfer . To meet high-speed data transmission, one of the possible solutions is terahertz (THz) frequency band which reduce the spectrum scarcity of current wireless communication system. The terahertz frequency band lies between the 0.1THz to 10THz. Although the frequency band below and above these band have extensively investigated but THz band is one of the least explored frequency band for future wireless communication . The higher bandwidth capacity and less attenuation is possible in THz frequency band . This frequency band has also different applications in medical imaging , defense and security based technology  and ultra-first spectroscopy of materials  etc. Internet of Thing (IoT) based devices may also be benefitted from THz spectrum .
In addition, high performance antenna is required to support THz band wireless communication. Microstrip patch antenna one of the possible solution to support THz communication. It has low cost, low profile, planner configuration, easy to fabricate and feeding, superior probability and easy to integrate with antenna elements like Monolithic Microwave Integrated Circuits (MMIC’s) [10–11]. Microstrip patch antenna has variety of application are mobile communication, personal wireless communications, radar, radio frequency identification (RFID), surveillance systems, aerospace telecommunications, weapons and missile, Global Positioning System (GPS) and many others [12–13]. The radiating patch is an important part of microstrip patch antenna. The uses of graphene as a radiating patch rather than copper materials is increasing day by day. Graphene is an allotrope of carbon packed into a two-dimensional (2D) honeycomb and hexagonal lattice structure. It is widely being used in Nano-photonics, Nano-electronics and THz wireless communication for outstanding chemical, mechanical and optical properties [14–16]. At room temperature, graphene carrier mobility is very high and may vary from 8000-200000 cm2 V − 1 s − 1. The carrier interband transition and carrier intraband transition are the two parts of graphene conductivity.
Different researcher has been studying on antenna that works in terahertz frequency for wireless communication for various application. Singh et al.,  has been presented trapezoidal microstrip patch antenna for THz wireless application with Photonic Band Gap (PBG) based substrate. They have shown that PBG substrate improves the performance of the antenna, like return loss, gain and bandwidth. Graphene based patch antenna on polyimide substrate in the frequency range 0.725–0.775THz has been analyzed and investigated by Anand et al., . Singhal et al., has been reported  hexagonal slotted antenna with microstrip feedline in terms of VSWR, input impedance, realized gain and radiation properties for 0THz-12THz frequency using polyimide substrate. Graphene based dipole antenna with tunable resonant frequency has been presented by Tripathi et al., . An elliptical microstrip patch antenna with polyimide substrate for THz wireless application reported by Singhal et al., . Their proposed antenna result has been described in terms of directivity, peak realized gain, radiation efficiency and VSWR. Rectangular microstrip patch antenna at 1THz resonant frequency has been proposed by Nickpay et al.,  for wireless communication.
In this paper, a graphene based microstrip patch antenna with using Silicon substrate has been proposed for THz applications. The main novelty of the proposed antenna has achieved reduction in size and larger impedance bandwidth. The photonic band gap (PBG) structure has been used in the propose antenna in order to enhance the antenna performance. The objective of the proposed antenna design is to improve the important antenna characteristics in terms of return loss, gain, VSWR and bandwidth. The simulated result of this paper shows that, propose antenna has minimal return loss − 48.95dB, gain 3.97dB, VSWR 1.054 and impedance bandwidth 26% which would be an excellent candidate for medical imaging, bio-sensing, explosive detection, chemical detection etc.
The rest of the paper is organized as follows. Section II presents design and configuration of the antenna. All the simulation results and discussion with previous studies has been reported in section III. Finally, section IV concludes the works.