volume | PIER Journals

Abstract

This paper presents a compact two-layer diplexer based on a vertically stacked architecture with hybrid filtering, in which a dual-band bandpass power divider (PD) is integrated with low-pass (LPF) and high-pass filters (HPF). The design utilizes a double-layer dielectric substrate: the upper layer integrates a dual-band bandpass filter (BPF) and a Wilkinson PD, while the lower layer incorporates low-pass and high-pass filtering sections. Metallized vias and impedance-matching networks are employed to enable tight inter-layer coupling and ensure excellent electrical performance within a miniaturized footprint. The results indicate that the proposed diplexer achieves insertion losses below 4 dB and 4.5 dB in the two passbands (3.4-3.8 GHz and 4.7-5.0 GHz), respectively (including the inherent 3 dB loss of the power divider), input return losses exceeding 13 dB and 11 dB, respectively, approximately 45 dB out-of-band rejection at ±400 MHz from the passband edges, and inter-port isolation better than 30 dB. These characteristics satisfy the stringent requirements for multi-band co-site operation in 5G base stations and terminal devices.

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Dr. Hongyun Guo

Prof. Tao Tang

Dr. Xiangyan Zhao

Dr. Melad M. Olaimat

Dr. Wei Hu