Design of Multilayer Dual-Band BPF and Diplexer with Zeros Implantation Using Suspended Stripline

Min-Hua HO  Wei-Hong HSU  

IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.7   pp.1195-1202
Publication Date: 2012/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.1195
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Trends of Microwave Systems and Their Fundamental Technologies)
dual-band,  suspended stripline,  diplexer,  quasi-lumped approach,  band rejection,  

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In this paper, a dual-band bandpass filter (BPF) of multilayer suspended stripline (SSL) structure and an SSL diplexer composed of a low-pass filter (LPF) and a high-pass filter (HPF) are proposed. Bandstop structure creating transmission zeros is adopted in the BPF and diplexer, enhancing the signal selectivity of the former and increasing the isolation between the diverting ports of the latter. The dual-band BPF possesses two distinct bandpass structures and a bandstop circuit, all laid on different metallic layers. The metallic layers together with the supporting substrates are vertically stacked up to save the circuit dimension. The LPF and HPF used in the diplexer structure are designed by a quasi-lumped approach, which the LC lumped-elements circuit models are developed to analyze filters' characteristics and to emulate their frequency responses. Half-wavelength resonating slots are employed in the diplexer's structure to increase the isolation between its two signal diverting ports. Experiments are conducted to verify the multilayer dual-band BPF and the diplexer design. Agreements are observed between the simulation and the measurement.