This paper presents design and simulation results of the cylindrical axial virtual cathode oscillator which is frequently used to damage electronic equipment by generating High Power Microwaves (HPM). Simulations are performed in MAGIC Tool Suite which uses FDTD-PIC algorithm to solve particle beam and field interactions. During the design procedure, AK Gap is changed from 5 mm to 12 mm and the scaling law is verified by simulation results. 9 mm AK gap values are selected as the most suitable one when output power and frequency of radiated field are taken into consideration. Further investigations are made by using 9 mm AK value in simulation environment. Formation of the virtual cathode is confirmed by Pz vs. z phase space diagram. The mean of applied input voltage value and input power value are found as 87.76 kV and 246 MW, respectively. The peak power and the average power for the generated microwave at the output are also 6.3 MW and 1.8 MW. Thus, power conversion efficiency for both peak and average output power are obtained as 2.56% and 0.73%, respectively. Frequency of the radial and longitudinal components of the produced electric field at the output is 2.92 GHz. Waveguide mode at 2.92 GHz is inferred from radial field distributions of fields and the propagating mode is found as TM01 at 2.92 GHz, which verifies our prediction.