Abstract: An RF filter includes elongate radiator elements constructed from printed circuit board (PCB) materials and using PCB fabrication techniques. The radiator elements are spacedly disposed and contained within a shielded enclosure. The filter apparatus has input and output leads exterior to the filter to pass a signal to be filtered. The filter is tuned by the shape and of the elongate radiator elements and shielded enclose and by conductive leads extending from the shielded enclosure toward the elongate radiator elements. The shape and number of the conductive lead elements may be varied to control RF coupling between radiator elements and the tuning of the filter.

Abstract: A filter described which includes helical resonator elements constructed using printed circuit board (PCB) materials and fabrication techniques. A helical resonator element is formed from conductive traces on either side of a double sided PCB substrate with interconnection of the traces using plated through holes to form a three dimensional serpentine or helical conductor path. Multiple resonator elements are RF coupled using ferromagnetic coupling elements. The shape and number of the coupling elements may be selected to control RF coupling between resonator elements and the tuning of the filter.