An electrical signal filter defined by a block of dielectric material with a top surface, a bottom surface, side surfaces, and through-holes extending between the top and bottom surfaces. In one embodiment, first and second walls protrude outwardly from the top surface and extend the length of first and second opposed longitudinally extending side surfaces. A surface-layer pattern of metallized and unmetallized areas is defined on selected surfaces of the block including an area of metallization that covers the top surface. In one embodiment, first and second surface-layer input/output electrodes are defined by first and second respective isolated strips of conductive material that extend from the top surface of the block and onto the first and second walls respectively.