coaxial resonator

Hi all,

I am designing a bandpass filter @ 2.8 GHz, 150 MHz bandwidth. I did a short survey on technologies but LC and LTCC are at the edge of what is acceptable, obviously due to the limited Q-factor of the resonators. An alternative is

/4 coaxial resonator filters. These are pretty cheap in higher volumes.

Has anyone designed filters with coaxial resonators? You can buy them in prepackaged module with a set of resonators soldered together, and trimming slot for frequency adjustment of the individual resonators. I would like to have more information about the design aspects of this type of filters, with capacitive coupling and individual resonator.

Thanks!

Mostly the resonator is turned by a turner into the shape you want. It is made of brass , steel or aluminum basicly. You can simulate the frequency of the resonator in HFSS by eigenmode solver. In coaxial resonator, less than 1/4 quarterwavelength , coupling is provide by fringing field and is predominate inductive. You can get capacitive coupling by placing Probe.

Added after 51 minutes:

Hope the following helps

Hello Radiohead,


Here is the attached PDF on LPF filter design using coaxial resonators,
using AWR Microwave Office (MWO) & MatLab...



---manju---