In this module, we describe cosimulation as a method of design. By definition, the method of cosimulation involves two or more simulation types that are performed to simulate a whole system. With cosimulation, a dynamic link is created between the two tools so that the changes in one tool is reflected in the other in real time. The power of cosimulation will be demonstrated with the help of a 5G phased array application. We will focus on the cosimulation abilities of the Ansys HFSS MCAD, HFSS ECAD and Circuit tools present in the Ansys Electronic Desktop. However, the cosimulation feature can also be used across different Ansys physics tools.