Y-Shape Dielectric Dual-Mode Resonator

In this paper, a new concept for a dual-mode dielectric resonator is presented, which is based on TM-mode operation in dielectric rods. By arranging the dielectric rods in Y-shape configuration, new fundamental eigenmode resonances are found to be present. The eigenmodes are coupled parallel to the input and output of the filter to result in a doublet coupling scheme. The filter was laid out by the global eigenmode approach. For filter configurations showing E-plane/H-plane mirror symmetry, the required parameters are determined and optimized by an eigenmode solver. A nonplanar Y-shape monoblock ceramic was constructed to achieve bandpass operation at 2 GHz. Measurement results of the constructed dual-mode filters are presented for the first time. The setup is suitable to demonstrate the zero-shifting property of the doublet by slightly adjusting the position of the ceramic inside the cavity. An unloaded quality factor of 4000 was extracted from the measurements. Good agreement between measured and computed results is obtained.