This research presents two graphene-based THz patch antenna structures for THz applications. The antennas are designed for 0.6 THz operation, with a silicon dioxide substrate and graphene patch. The reconfigurable properties are achieved by adjusting the chemical potential or bias voltage of the graphene patches. The first antenna shows an S11 less than -10 dB from 0.58786 THz to 0.63112 THz, with a maximum efficiency of about 65%. The second antenna has an S11 less than -10 dB from 0.57814 THz to 0.63391 THz, with a maximum efficiency of about 72%. Both antennas exhibit peak realized gains, radiation efficiencies, far-field 2D radiation patterns, VSWRs, current distributions, envelope correlation coefficients, and diversity gains over the operating frequency band. Graphene-based quad-port MIMO reconfigurable antennas have significant applications in 5G and satellite communications (SATCOM). In 5G networks, these antennas can increase communication speed, network coverage, and capacity by optimizing radio waves and enabling simultaneous data transmission through multiple transmitters and receivers. In SATCOM systems, they can improve communication speed, satellite coverage, and system capacity by allowing accurate and intelligent signal transmission. The advantages of these antennas include high data rates, reconfigurability, compact size, and low power consumption, making them suitable for various applications requiring fast and reliable data transmission. The use of graphene unit cells between patches can help reduce mutual coupling, improving antenna performance. This research highlights the potential of graphene-based antennas in future communication systems.This research presents two graphene-based THz patch antenna structures for THz applications. The antennas are designed for 0.6 THz operation, with a silicon dioxide substrate and graphene patch. The reconfigurable properties are achieved by adjusting the chemical potential or bias voltage of the graphene patches. The first antenna shows an S11 less than -10 dB from 0.58786 THz to 0.63112 THz, with a maximum efficiency of about 65%. The second antenna has an S11 less than -10 dB from 0.57814 THz to 0.63391 THz, with a maximum efficiency of about 72%. Both antennas exhibit peak realized gains, radiation efficiencies, far-field 2D radiation patterns, VSWRs, current distributions, envelope correlation coefficients, and diversity gains over the operating frequency band. Graphene-based quad-port MIMO reconfigurable antennas have significant applications in 5G and satellite communications (SATCOM). In 5G networks, these antennas can increase communication speed, network coverage, and capacity by optimizing radio waves and enabling simultaneous data transmission through multiple transmitters and receivers. In SATCOM systems, they can improve communication speed, satellite coverage, and system capacity by allowing accurate and intelligent signal transmission. The advantages of these antennas include high data rates, reconfigurability, compact size, and low power consumption, making them suitable for various applications requiring fast and reliable data transmission. The use of graphene unit cells between patches can help reduce mutual coupling, improving antenna performance. This research highlights the potential of graphene-based antennas in future communication systems.