Design of THz low pass filter using split-ring resonators

Abstract

This paper is about the designing of a passive low pass filter working in the terahertz spectrum constructed from split-ring resonators (SRR) along with raising the level of performance and optimizing the parameters like insertion loss and return loss of the filter. The split-ring resonators have been optimized after a periodic arrangement running parallelly along the center of finite conductor microstrip line. The final filter was designed after testing various SRR array structures. The computed outcome of the filter shows a cut-off frequency at fc = 6.4 THz. The filter shows a satisfactory bandwidth with a low insertion loss. The structure is created using copper of thickness t = 0.035 µm as the microstrip as well as the ground. The substrate used is polyimide with a relative dielectric constant εr = 3.5, loss tangent (tan δ = 0.0027) with a height h = 1.6 µm. The entire dimension on which the filter resides is an area of 35.48 × 21.15 µm2. CST-Design Environment was used to design the schematics and the to plot the response of the filter. The originality of this work is on enhancing a passive LPF by individually adding a unit cell of SRR to the filter.