BSST high-permittivity coaxial-type direct-coupling microwave ceramic bandpass filters

Dielectric resonators with a high dielectric constant (70-90) are commonly applied in UHF cellular telephone and L-band communication systems. With the advantages of compact size and ruggedness, dielectric resonators can be constructed as high-performance bandpass filters through direct coupling. Coaxial-type direct-coupling microwave ceramic bandpass filters are investigated in this paper. The filters exhibit excellent features of low dissipation and relatively good temperature stability due to their high-Q dielectric material and low temperature coefficient of resonant frequency (τ_f). This paper describes the performance of a high-permittivity ceramic coaxial-type direct-coupling microwave bandpass filter and the effect of aperture location on its response.