Abstract: A temperature compensated microwave filter has end caps and irises that each contain a projection that extends into a cavity to reduce the volume change of the cavity that would otherwise occur with changes in temperature due to an expansion or contraction of the side walls. The end caps and irises are formed from a single material. The material has a more positive coefficient of thermal expansion than the coefficient of thermal expansion of the side walls of each cavity. While one material is used to make up each end cap or iris, it is not necessary that the same material be used for all of the end cap and iris components.