a filter described which includes helical resonator elements constructed using printed circuit board 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 .