Is there any one can introduce a good circulator?
I want a 200W cw 1.7-2.2ghz circulator, and 2nd Harmonic suppression needs to be better than 25dbc@200W cw to reach -60dbc.
Thanks!
Try google for high power circulator. Those types may be only custom-made as the power is high and frequency quite special.
circulators do not have 2nd harmonic suppression built into them. add a lpf if u need that. You might luck out with higher loss at the 2nd harmonic, but no guarantees
Thank you for your reply. Now I faced a problem is that, when Pout=200W cw, before circulator, the 2nd harmonic is -50dbc, but after the circulator it becomes -45dbc. Do you know why that happened?
But at very low output power like 20W, the circulator gives a 20dbc compression for 2nd harmonic.
I have used only low-power circulators so I cannot explain your observation. If you need to suppress the 2nd and higher harmonics, I think the only good solution is to use a low-pass filter, before or after the circulator.
Ferrite devices like circulators are designed for a particular band and bandwidth. To my knowledge no manufacturer is interested in device behavior outside of a specified bandwidth.
Ferrites can be non-linear devices,mainly at power levels > 10W like in your case. Expect more interesting problems and make sure you can add filters to solve them.
2nd harmonic is a popular parameter for us， our customers always ask us to reach at least 20dB，even in the condition of temperature