A 60 GHz embedded SIW (substrate integrated waveguide) BPF Considering the Transition Effect

This paper presents embedded substrate integrated waveguide (SIW) BPF and microstrip line-to-embedded microstrip line transition based on LTCC for 60-GHz application. The embedded SIW BPF is placed in LTCC substrate for compact system and integrated passive and active device on the other layer. But embedded SIW BPF performance is changed by interconnection via and transition. In order to low-loss interconnection with embedded passive device, microstrip line-to-embedded microstrip line transition with compensation circuit using series and shut line is proposed and implemented. The insertion loss of fabricated transition with compensation circuit is approximately 1 dB and return loss is below 10 dB from 56 GHz to 69 GHz. The proposed embedded SIW BPF including transition with compensation circuit exhibits a total insertion loss 2 dB at 61.8 GHz and the return loss is better than 16.2 dB with a 3-dB fractional bandwidth of 11.7 % (7.23 GHz). The measured insertion loss is lower than those in previous works. The overall size of the fabricated filter is 8 mm × 2.7 mm × 0.3 mm.