Multilayered Stub Loaded-SIR for Compact Dual-BPF and Quad-channel Diplexer Design

This paper considers a novel design technique of compact dual-BPF and four-channel diplexer for a multiservice communication system.The suggested dual-band passband filter is constructed by a double-layered stub loaded-stepped impedance resonator (SL-SIR), leading to a tiny circuit area, and lightweight, low cost, and good characteristic performance.Herein, the SL-SIR resonant oddmode is used to realize the first passband, while the resonant even-mode is used to realize the second passband.Also, the proposed three-port quad-channel diplexer is performed by two different double-layered dual-passband filters, which also have a very compact circuit area.For practical verification, a two-passband filter working at 2.5/4 GHz with a circuit area of 91.7 mm 2 and a four-channel diplexer working at 2.5/4 GHz and 3.5/5.2GHz with a circuit area of 0.0639 g 2 excluding feeding ports are designed, manufactured, and measured.The electromagnetic simulated and measured responses are compared and discussed.Obviously, the comparison shows good agreement improving the expected filtering response.The diplexer offers insertion/return losses of about (0.44/0.74) dB/(0.45/1.12)dB for channel 1/channel 2, and (21.30/21.72)dB/(19.81/20.54)dB for channel 3/channel 4.