An apparatus includes a filter. The filter includes a metal structure forming a cavity and includes a ceramic block, which is suspended in the cavity. The ceramic block has two removed portions, the removed portions removed from two opposing sides of the ceramic block. The ceramic block further has one or more slots that that span a region of ceramic between the two removed portions and connects chambers formed by the two regions with chambers formed by the one or more slots, wherein a combined structure of the ceramic block, cavity, and metal structure supports multiple fundamental TM modes and one fundamental TE mode. The filter comprises multiple coupling structures to couple radio frequency signals into and out of the filter. The apparatus may include multi-cavity filters including one and typically multiple ones of the filters.