Dielectric ring resonator band pass filter for 2.4 GHz WLAN frequencies

A Microwave band pass filter employing dielectric ceramic ring resonator is designed, fabricated and tested. Band pass filter characteristics are studied by measuring the return loss and transmission characteristics of the microstrip line fed dielectric ring resonator. S-parameters, electric field and magnetic field distributions are computed using FEM method and compared with measured results. The measured values agree with predicted values obtained using FEM. Centered at 2404 MHz the fabricated dielectric ring resonator filter shows a measured 3-dB band width of 20.6 MHz.