A novel compact Ultra-Wideband bandpass filter

This paper presents a novel approach which can be used to design compact Ultra-Wideband (UWB) filters with high selectivity and excellent stopband performance. The design is based on a new 4-pole wideband filter circuit that provides transmission zeros to enhance the selectivity. In addition, the proposed design can be easily implemented on multilayer substrates with simple and low-cost manufacturing process. To demonstrate this, the filter has been fabricated on multilayer LCP substrates and has a compact size of 5.6mm × 5.6mm × 0.4mm (0.2 λ_g × 0.2 λ_g × 0.014 λ_g), where λ_g is the guided wavelength at 6.85GHz. This size is quite small as compared to other designs in open literature with similar performance. The measured frequency responses of all fabricated samples of this design are in very good agreement with simulation. This indicates that the design is a good candidate for practical UWB applications and very suitable for mass production with high yield.