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Faculty of Graduate Studies

Saeid Asadi

Notice of the Final Oral Examination for the Degree of Master of Applied Science

Topic

Design and Testing of a Terahertz Bandstop Filter Using Varying Radii Split-Ring Resonators

Department of Electrical and Computer Engineering

Date & location

  • Tuesday, August 20, 2024

  • 10:00 A.M.

  • Engineering Office Wing

  • Room 430

Reviewers

Supervisory Committee

  • Dr. Thomas Darcie, Department of Electrical and Computer Engineering, 番茄社区 (Co-Supervisor)

  • Dr. Levi Smith, Department of Electrical and Computer Engineering, UVic (Co-Supervisor) 

External Examiner

  • Dr. Andrew MacRae, Department of Physics and Astronomy, UVic

Chair of Oral Examination

  • Ms. Anne Grimm, School of Music, UVic

     

Abstract

The terahertz (THz) band which ranges from 0.1 THz to 10 THz has been relatively unexplored when compared to other frequency bands due to the unavailability of sources and detectors. However, continual advances in technology have made this frequency band more accessible and have attracted attention because of unique applications such as imaging, spectroscopy, communications, and physical defect detection. In many applications throughout the electromagnetic spectrum signal filtering is used to improve signal-to-noise ratios. One method to filter signals is using split-ring resonators (SRRs) that are made of nonmagnetic metals which respond to electromagnetic waves like a magnetic medium. SRRs at their resonant frequency create a magnetic dipole so that they can stop or pass electromagnetic waves. This property has made SRRs a commonplace element in the design of metamaterials (MTMs). This thesis does not focus on the investigation of MTM properties and characteristics (negative permittivity or negative permeability), but it does provide some of the relevant background and theory.

This thesis reports a proof-of-concept terahertz band-stop filter constructed from SRRs that has a center frequency of 1.06 THz and a -3 dB bandwidth of 0.36 THz. The design consists of nine SRRs of varying radii (3×13 μm, 3×14 μm, 3×15 μm) that are placed between the conductors of a coplanar stripline (CPS). The response of the filter is measured using a modified terahertz time-domain spectrometer and a reasonable agreement between simulation and experiment was found. This work demonstrates the viability of using varying-radii SRRs as discrete subwavelength filter elements for THz systems. In addition, the ABCD matrix approach was utilized to get the transmission response of the equivalent circuit. This filter was fabricated using gold on a thin Si3N4 substrate, and the simulated data are in good agreement with the experimental results.

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