Tunable Bandpass Filter Design Using Paraelectric Oxide Single Crystal Substrates

The fixed response frequency of conventional bandpass filters poses challenges in emerging ultra-wideband (UWB) communication systems, where universal radios capable of spanning extremely wide frequency ranges are anticipated. A pivotal enabler for such systems is the development of reconfigurable filters, particularly ultra-fast tunable bandpass filters. Among the promising approaches, integrating high-K dielectric crystals offers a means of achieving frequency agility by altering the effective dielectric properties of the propagation medium by changing their position, resulting in a shift in the operational band. In this study, we demonstrate a tunable bandpass filter (BPF) employing a paraelectric oxide single-crystal substrate with ultra-low loss within a passive microstrip filter architecture. Preliminary analysis reveals a resonance band shift from 11.8 to 12.2 GHz, exhibiting high-Q, thus highlighting the efficacy of this approach for frequency reconfigurability in next-generation communication systems.