Abstract: A ceramic filter (10) is shown and described. The filter (10) has a filter body having top (14), bottom (16), and side surfaces (18, 20, 22 and 24) with through holes (26, 28) extending from the top (14) to the bottom surfaces (16) defining resonators. The surfaces are substantially covered with a conductive material defining a metallized layer, with the exception that the top surface (14) is substantially uncoated, and with an additional exception that a portion of a side surface is substantially uncoated in proximity to the top surface (14) and extending at least in proximity to between the resonators (26, 28), defining an unmetallized coupling region for electrically coupling the resonators. The filter (10) also has first and second input-output pads (34, 38) on a side surface for facilitating connection to a circuit board, for example.

Abstract: A ceramic filter (120) with at least one transmission zero is disclosed. The filter (120) has a filter body comprising a block of dielectric material and having top (110), bottom (112), and side surfaces, and having metallized through-holes extending from the top to the bottom surfaces defining resonators. The surfaces are substantially covered with a conductive material defining a metallized layer. The top surface (110) is uncoated. The filter (120) can also include input-output pads ( 104, 106). The bottom surface (112) has a channel (108) defining a magnetic coupling between the resonators. The channel configuration and placement can vary depending on the desired frequency response.

Abstract: A ceramic filter with a high side transmission zero. The ceramic filter (10) has: a filter body (12) of a dielectric material having top, bottom and side surfaces (14, 16, 18, 20, 22, 24). Two through-holes extending from the top (14) to the bottom surface (16), defining resonators (26,28) are included. The surfaces are substantially covered with a conductive material, defining a metallized layer (30), with the exception that the top surface (14) is substantially uncoated and with the additional exception that a portion of the side surface is also uncoated (32) in proximity to the bottom surface (16), and it extends laterally at least in proximity to the resonators (26,28), defining a magnetic transmission line (32) for magnetically coupling the resonators (26,28). Surface mountable first and second input-output pads (34,38) are also provided.

Abstract: An adjustable electronic filter apparatus is disclosed comprising a dielectric block having one or more through-holes and having a conformal conductive coating substantially over all outside surfaces as well as each through-hole therein. Each through-hole so plated forms a resonator from a transmission line which includes an open portion, for providing capacitive reactance at a first end, and a short-circuited end as a base, for providing an associated distributed inductance at a second end thereof. A unique method of tuning the adjustable electronic filter, whether a single resonator, a plurality of resonators, or a plurality of intercoupled multi-resonator filters, is disclosed that permits bi-directional tuning for at least one resonator in each of the above exemplary embodiments. By selectively adjusting an inductive portion of the plating at the base of each resonator so tuned, a resonator is quickly and accurately adjusted to a desired frequency.