Multi-Resonator Bandpass Filter with Hollowed-Out Regions

The patent divides the traditional long-length resonator into multiple short resonant holes arranged in parallel within a compact block. Instead of using one continuous long resonator, the invention segments the resonating structure into several discrete holes (e.g., five resonant holes) that work together to achieve the same filtering function in a much smaller volume, directly resolving the contradiction between electrical performance and size.

The invention transitions from a one-dimensional long-length resonator structure to a three-dimensional compact block with multiple resonant holes. By arranging resonant holes in parallel within a block and using hollowed-out regions to enhance coupling, the design exploits spatial dimensions to achieve compact size while maintaining the resonating function, thus reducing filter size from centimeter level to much smaller dimensions.

The patent introduces hollowed-out regions with specific geometric configurations (first hollowed-out region around resonant holes, second hollowed-out regions at top surface) to locally enhance electromagnetic coupling and field distribution. These localized structural modifications improve the electrical characteristics in the compact structure by optimizing the electromagnetic environment in critical regions, counteracting the deterioration that would normally occur with size reduction.

The invention uses a composite structure combining dielectric block material with metallic ground layers and resonant coating layers. This composite approach allows the compact filter to maintain good electrical characteristics by utilizing the complementary properties of different materials - the dielectric block provides mechanical support and basic resonating, while the metallic layers provide ground reference and enhanced coupling, compensating for the effects of reduced size.