A Study on Vertically Installed Planar (VIP) Combline Bandpass Filters via 3D-FDTD Method

Chuandong ZHAO  Ikuo AWAI  

IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.4   pp.602-607
Publication Date: 1998/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Components
VIP structure,  combline BPF,  3D-FDTD,  versatile bandwidth control,  attenuation poles,  

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A two stage Combline Bandpass Filter (C-BPF) of the Vertically Installed Planar (VIP) structure has been investigated, which is essentially composed of a strongly coupled microstrip lines terminated with a planar fin and through-hole combined with the tapping feed approach. The principle and performance of this filter is studied approximately by an equivalent circuit model and also by the normalized 3D-FDTD method more exactly. The time domain iteration in the FDTD analysis is performed in an expanded time dimension resulting in a reduced CPU time. Some of the obtained numerical results are compared well with the measured ones. A modified VIP combline BPF has the advantages of simple structure, easy tuning, low cost, versatile bandwidth control and good skirt characteristics brought about by two attenuation poles.