Design and Fabrication of a Compact 3-Dimensional Stacked Type Dielectric Ceramic Waveguide Bandpass Filter

A compact 3-D stacked type waveguide structure is proposed for supporting the modern communication systems in the L-band frequency (700-900 MHz). The proposed structure can achieve very small size in comparison with a standard metal cavity filter designed at 900 MHz center frequency with a 3% fractional bandwidth. The design for this filter was developed with the High Frequency Structural Simulator (HFSS) and a Direct coupled Waveguide Filter Design (DWFD) program based on the direct coupled filter of λ/2 line impedance prototypes. This waveguide filter was designed by 8 poles with bandwidth 27.8 MHz at the center frequency 881 MHz with a ceramic material (εr=35.4). The measured result was in good agreement with the simulated responses and confirmed the accuracy of the design method.