Abstract: With the development of spacecraft payloads toward high power and miniaturization, the problem of passive intermodulation (PIM) of high power filters has become an important issue that restricts the development of spacecraft payloads. The factors of generating passive intermodulation in highpower coaxial filter used in spacecraft were researched and explored which found the influence rules on passive intermodulation of different surface coating treatments and adjusting ways of screws by different materials. In this paper, a S-band low-passive intermodulation coaxial filter was designed according to the contact made between the inner conductor and the feeding pole of the dielectric isolated coaxial connector. Compared with the traditional coaxial filter,the passive intermodulation of the new one can be effectively reduced by 20dB. This shows that the method is effective to reduce the passive intermodulation of high power microwave components and can be used in high power microwave and ground mobile power components.

Key words: coaxial filter, passive intermodulation (PIM), feed, dielectric, welding