K-band bandpass filter using fully micromachined substrate integrated waveguide platform with dual copper posts in glass dielectrics

A K-band bandpass filter (BPF) based on the fully micromachined substrate integrated waveguide (SIW) structure has been demonstrated. In the proposed SIW platform, borosilicate glass reflowed into the silicon trench is used as a dielectric substrate, and the vias are formed by filling the glass mould with electroplated copper after removing the embedded silicon part. The BPF´s characteristics are realised by introducing dual inductive post structures into the SIW platform. The insertion loss and 3 dB bandwidth of the fabricated BPF were measured to be 2.46 dB at 29 GHz and 7.2%, respectively. The proposed BPF platform has high potential for low-loss, compact SIW-based millimetre-wave tunable filters owing to its mechanical robustness and integrity with MEMS tuning devices.