In high-performance aircraft, spacecraft, satellite, and missile applications, where size, weight, cost , performance, ease of installation, and aerodynamic profile are constraints, low profile antennas may be required. The growing demand of wireless applications has presented RF engineers with continuing call for low cost, power efficient, wide- bandwidth, with high data rate and small size system designs. The basic communication establishing component of any wireless system is its antenna. Among the existent antenna, the Microstrip antennas are widely employed because of their unique advantages. Terahertz (THz) radiation is electromagnetic radiation whose frequency lie between the microwave and infrared regions of the spectrum. this part of the electromagnetic spectrum remains the least explored region mainly due to the technical difficulties involved in making efficient and compact THz sources and detectors. Graphene material exhibits numerous attractive pure multi-physics, electrical and mechanical properties the carrier concentration and chemical potential in graphene based patch antennas can be adjusted through bias voltage which results in tunable characteristics highly desirable for electromagnetic applications. The purpose of this thesis is design and simulation of a improved microstrip antenna in terahertz band. An algorithm for designing graphene based terahertz microstrip patch antenna is presented which its results in compare with the other works are satisfiable. Keywords 1- Antenna 2- Microstrip patch 3- Terahertz 4-Graphene