must fabricate

I fabricated the waveguide filter in this way:a cover and a cavity,and connect them with screws.but find the response is poor,and s11**2+s22**2 is not equal
to unity.so is the fabrication leads to power leakage?the s11 is -10db and s21 is -10dB.
is it a must we must fabricate waveguide line firstly,and then insert posts into it?
if not,why the response becomes so poor?

Liu Yun

Dear amicloud,

I have same experiance of phenomenon. Of course, I don't know the fabrication situation; structure of filter. I guess you apply inductive iris filter.

The problem is the flatness of surface in body and cover.

Small gap exists in connect plane. And if you fabricate it by CNC, body is twist, maybe.

You must check it.

I suggest method.

1. grinding.
2. solder cream including silver
3. more many screw

If you share structure, I can check it more detail.

Thank you.

dear HOHOH,
thank you so much. I will try your methods.

good luck with your everyday life!