LAUSR

Abstract This paper presents a compact quad-band bandpass filter (QB-BPF) using double-diplexing structure, which consists of two channel filters and a pair of modified manifold-coupled lines. Each channel filter is realized by the asymmetrical coupling shorted stub loaded stepped-impedance resonator (SSLSIR) dual-band bandpass filter (DB-BPF), and the modified manifold line constructed by lumped elements is proposed to connect two channel filters to constitute the QB-BPF. The fabricated QB-BPF occupies a compact circuit size of 0.178λg × 0.219λg. Good agreement is shown between the simulated and measured results.