DIELECTRIC FILTER

PURPOSE:To adjust the frequency band depending on the relative width of the dielectric block, to obtain a flat surface and also to reduce the working time by selecting a width of a part of resonance holes close to a central resonance hole among plural resonance holes provided to a dielectric block larger than a width of part of other holes closer to the other resonance holes. CONSTITUTION:Three resonance holes 11-13 penetrated in the vertical direction of a box-shaped dielectric block 10 are provided in the lengthwise direction at a prescribed interval in parallel and coupling holes 14, 15 are provided between adjacent resonance holes. Moreover, the front face is formed to be an open face and the bottom face is formed to be a short-circuit face and a conductive film (not shown in figure) is formed to other side faces, the bottom face and inner faces of each resonance hole except the open face by metallizing or the like. The feature of the dielectric filter is that the width B3 of the part having the center resonance hole 12 is selected larger than the width B1 of the part having the other resonance holes 11, 13. That is, the filter is formed as a cross in plain view. Thus, the frequency band is adjusted depending on the width of the block.