Mechanically reconfigurable cavity filters using liquid metals in the W-band

The high adaptability and flexibility of reconfigurable cavity filters (RCFs) provide a compelling solution for signal modulation in communication systems. However, current reports on these filters are predominantly concentrated within the frequency range of a few GHz. As communication frequencies continue to escalate, there is a pressing need for filters that can operate at higher frequencies. This study presents a mechanical RCF operating in the W-band (75-110 GHz) that address the need for high-frequency cavity filters. The reconfigurability of the filter is enhanced by adjusting the height of the liquid metal posts and interchanging different liquid metal (LM) media, thereby augmenting its tuning flexibility. During the experiment, we observed the potential dispersion effects of the LMs near 100 GHz, which were hypothetically validated. Finally, we tested the performance of the RCF with single or double LM tubes using a vector network analyzer to achieve consistency between the experimental and simulated results. This study offers a unique solution for sub-terahertz communication systems with critical requirements for dynamic filtering capabilities.