Design of two-stage fish spear-shaped UWB bandpass filter with sharp selectivity and good out-of-band performances

Abstract

In this paper, a novel two-stage fish spear-shaped multimode resonator (MMR)-based ultra wideband (UWB) bandpass filter (BPF) is presented. The fish spear-shaped MMR is loaded with stepped impedance resonator in order to improve the out-of-band performance of the proposed filter. The proposed UWB BPF filter has fractional bandwidth better than 110%. In order to validate the present design approach, the filter is fabricated on RT/Duroid 5880 having dielectric constant 2.2, thickness 0.787 mm and loss tangent of 0.0009. The measured passband bandwidth of the filter is from 3.3 to 11.85 GHz, with insertion loss of 1.5 dB and return loss better than 12 dB in the passband. The proposed filter has sharp selectivity and upper stopband with 20 dB attenuation from 12 to 24 GHz.

Design of wideband comb shape substrate integrated waveguide multimode resonator bandpass filter with high selectivity and improved upper stopband performance

“…Figure shows the schematics of two‐stage comb‐shaped MMR‐based filter cascaded together to enhance the out‐of‐band performance and skirt rate of filter . The optimized dimensions of this MMR based filter are (all the dimensions are taken in mm): W SIW = 12, L SIW ′ = 28, D = 1.2, P = 2.4, R = 1.5, L = 3.15, T = 0.45, G′ = 0.60, H′ = 2.55, S = 7, W T = 5, L T = 3.50.…”

“…The present design is proposed on the basis of previous works on stub loaded resonator by refs. []. In this design, comb‐shaped slot etched on top metallic plane of SIW structure is used to form a resonator.…”