This letter presents a compact tri-band bandpass filter (BPF) with controllable bandwidths. The proposed filter employs dual-mode resonators, i.e., crossed open-short stub loaded resonators and tri-section stepped impedance resonators. The center frequencies and bandwidths of the three passbands can be conveniently controlled by tuning the dimensions of two resonators. Moreover, on each side of each passband, there is at least one transmission zero, resulting in high skirt selectivity. To validate the design and analysis, a prototype of tri-band BPF is fabricated. Good agreement can be found between the measured and simulated results. Index Terms-Tri-band bandpass filter, Crossed open-short stub loaded resonators, Stepped impedance resonators.

There has been an outstanding improvement in injection technology in the spark ignition (SI) engines’ fuel supply systems, from traditional carburettors with throttle body injection (TBI), manifold port or multi-point injection (MPI) to direct injection (DI). This paper has developed an MPI intake manifold model and investigated fuel injector angles using a multiphase CFD package provided by FloEFD software. A wide range of injector angles from 22 to 30 degrees has been investigated in order to evaluate the influence of the injector angle on the wall-wetting issue, a critical problem of manifold injection systems in SI engines. The intake air pressure differential in the manifold was also evaluated. The results show that the fuel injector angle affects the multiphase flow in the MPI system. The manifold diameter meets the design specifications, and the pressure differential in the manifold is quite small. With an injector angle of 25 degrees, the wall-wetting issue is minimal. This model could be used for further studies on engine performance and emission formation.

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