Miniaturized and Ultra‐Wide Stopband Filter Using SISL Metasubstrate

ABSTRACT This letter proposes miniaturized and ultra‐wide stopband bandpass filters (BPFs) by partially loading metasubstrate half‐wavelength resonators and cascading metasubstrate low‐pass filters (LPFs) on substrate integrated suspended line (SISL). To achieve miniaturization and ultra‐wide stopband of BPFs based on SISL technology, firstly, the partially loaded metasubstrate half‐wavelength resonator (PLMHWR) is designed. Then, miniaturized metasubstrate LPF is introduced to expand the stopband of the BPF without obviously increasing the size of filter. Finally, to verify the effectiveness of our idea and the design method, the third‐order and fifth‐order metasubstrate BPFs with cascaded metasubstrate LPF on SISL are designed. The proposed fifth‐order BPF only shows a compact size of 0.23 λ g × 0.46 λ g with 40 dB rejection up to 17.4 times the center frequency ( f 0 ).