Bandwidth simulation of coaxial cavity coupled with waveguide filter by transmission method

The klystron output circuit of double coupled cylindrical coaxial cavity loaded with waveguide filters is designed and analyzed with two-port microwave network model theory. The output waveguide port is regarded as the first port, the drift tube gaps in cavity as the second one. By sweep frequency simulation with CST software, the change of scattering parameters square S
21
²
with the frequency shows that the output circuit 3dB bandwidth is about 0.36GHz, relative bandwidth ΔF/F
0
≈ 3.7%.