A very small dielectric planar filter for portable telephones

A high performance, high-dielectric stripline filter with the size of 4.5 mm/spl times/3.2 mm/spl times/2.0 mm has been developed. The filter consists of planar resonators and its structure is made of high permittivity multilayer ceramic in the Bi-Ca-Nb-O system. The performance is distinctive with its attenuation pole. An equivalent lumped circuit is derived to explain the behavior of the attenuation pole quantitatively. A precise design procedure is also described.<
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