Abstract: Arrangements for a frequency adjustable filter, which includes at least a housing, which includes one or more cavities closed by a lid above the housing are disclosed. In an arrangement, there is, per a cavity forming a resonator, a first resonator element extending from the lid, a second resonator element extending from the bottom, the second resonator element partially overlapping the first resonator element, an adjusting bar extending inside an area in which the first and the second resonator elements are overlapping, the adjusting bar being arranged to move within said area, a first hole either in the lid or in the bottom, a driving shaft, and an actuator arranged to move the adjusting bar through the first hole by means of the driving shaft. At least the first resonator element, the second resonator element and the adjusting bar are positioned to have a common vertical central axis.