Bandstop filter module with shunt zero

摘要

A bandstop filter module (200) with a shunt zero is provided. The module (200) contains a circuit substrate (202) with input and output pads and transmission lines (208). The module (200) also contains at least one dielectric monolithic block (210) mounted to the circuit substrate (202) having a plurality of metallized through holes defining resonators (224) and guard holes (226). All surfaces of the dielectric monolithic block (210) are substantially covered with a conductive material with the exception that the top surface (212) is selectively metallized providing an unshorted metallization pattern (228) relative to a ground plane in proximity to the guard holes (226). The guard holes (226) and the unshorted metallization pattern (228) provide a shunt zero in a frequency response curve of the module (200). The module also contains means for coupling each of the resonators (224) with the transmission lines (208) on the circuit substrate (202). Other module components include at least one inductor coil (230) mounted on the circuit substrate (202) and a shield (232) having tuning windows.