Dual-band Band-pass Filters Based on Metallic Via Holes

This paper presents compact dual-band band-pass filters (BPFs) using microstrip transmission lines (TLs) loaded with metallic via holes (MVHs). The primary goals of the proposed design are to get size reduction and dual-band frequency response. An end-coupled line dual-band BPF with better size reduction has been obtained using MVHs as a single negative (SNG) metamaterial (MTM) component to achieve negative relative permittivity (ɛr). This component is adequate for designing dual-band BPFs to operate at 4.1 GHz and 6 GHz resonant frequencies. To the best knowledge of the authors of this work, “Dual-” band BPF based on MVH has not been experienced yet by any other work in the literature. The filters structure length is as small as one third of wavelength. The filters have been designed with a fractional bandwidth (δ) that exceeds 10% at the resonant frequencies. Numerical observations of the microstrip TL and end-coupled BPFs designs have all been discussed. Simulations were done by HFSS software and implemented on the substrate Roger RO3210 with dielectric constant of 10.8 and dielectric substrate height of 1.27 mm. These filters are convenient for most common microwave applications.