Compact 12–18-GHz Bandpass Filter with Wide Stopband Using Hybrid Dual-Mode SIDGS/Microstrip Resonant Cell

In this paper, a compact 12–18-GHz bandpass filter (BPF) with wide stopband is proposed for Ku-band satellite applications. The stacked-coupled hybrid dual-mode substrate-integrated defected ground structure (SIDGS)/microstrip resonant cell is introduced to generate a wide passband response with high selectivity in a compact size. In addition, stepped-impedance feed-lines are utilized to extend stopband width, while the self-shielded structure can finely suppress the radiation leakage. To verify the mechanism, a BPF operating at 15 GHz (i.e., center frequency f
0
) with a 3-dB fractional bandwidth (FBW) of 52% and wide stopband up to 60 GHz is implemented and fabricated. Such BPF is suitable for system integration with a 4×2.7 mm
²
core circuit size.