Miniaturized Filtering Devices Based on Multi-Mode Dielectric Resonators

This paper presents three filtering devices using high-Q quad-mode dielectric resonator (DR) including a frequency-agile dual-band balanced filter, a dual-band diplexer and a balun diplexer. Based on the field distribution, the quad-mode excitations and differential-mode (DM) operations are both revealed only using straight probes. According to the quad-mode orthogonality, the independent controls and individual transmissions of the multiple modes are investigated. Then the independently tunable passbands and high isolation between different channels are both realized. For verification, the first two devices are both designed and fabricated. By sharing the quad-mode DR, the compact sizes are ensured. The measured result agrees well with the simulated one, supporting the proposed method in miniaturized multi-band DR designs.