A Novel Surface-Mounted Monoblock Dielectric Filter

A novel surface-mounted monoblock high Q dielectric filter is presented in this paper. The proposed filter is constructed on the basis of a surface-metalized dielectric monoblock and is surface mountable on a printed circuit board (PCB) by means of a reflow process. The monoblock dielectric filter can be easily manufactured by mold casting. Metal caps on the surface and through holes in dielectric body are introduced for tuning capability. The input/output coupling is realized by inserting a stepped probe into the dielectric cavity through a via structure on the PCB. A novel electric coupling method using microstrip line is presented for easy control of coupling coefficient by adjusting the length and width of the microstrip line and flexible routing of cross couplings. One prototype 8-2 surface-mounted monoblock dielectric filter operating at 1.9 GHz with 84 MHz bandwidth is designed, fabricated, and measured. The measured insertion loss at center frequency is 0.73 dB with 0.6 dB ripple and corresponding unloaded Q factor of around 1700, demonstrating that the proposed filter architecture is applicable to a radio front-end of advanced wireless communication systems.