Design of an Ultra-Wideband Bandpass Filter for Millimeter Wave Applications

Abstract

The advancement in filter designs for ultra-wide frequency spectrum are accelerated highly in this technological era. The main goal is to avoid interference of spurious signals with the authenticated signals resulting into counterfeiting of outcomes. This paper depicts the designs of Ultra-Wideband Bandpass filter (UWB BPF) with three different structures; using dual shunt ring resonator, split ring resonator and square patch resonator embedded at the centre of two parallel coupled microstrip lines. These designs are proposed with enhanced filter characteristics than conventional designs for millimeter wave range in automotive applications with improvement factors like traffic alerts and lane change assist. The frequency spectrum of 22-29GHz is used to meet FCC specifications along with 25.5GHz as the centre frequency. The complete simulations of the proposed designs are carried out using HFSS V13 software utilising RT/Duroid 6002 as a substrate with dielectric constant of 2.94. All designs are fabricated on the same substrate with equal substrate area of 5.8mm*2.8mm and thickness of 0.127mm. The return losses are 14dB, 16dB and 36dB and insertion losses are 0.4dB, 0.39dB and 0.30dB respectively of the proposed designs. The large fractional bandwidth of nearly 40%, high selectivity up to 82dB, especially in case of dual square patch resonator design, are extracted.