Terahertz Time Domain Transmission Spectroscopy of Magnetic Nanoparticles for Frequency Selective Surface Application

Terahertz time-domain spectroscopy (THz-TDS), is an effective method for characterizing materials and monitoring processes. Metals, electronics, 2D materials, and even superconductors have all been tested with this technique, which does not require physical touch to obtain accurate results. Terahertz (THz) spectroscopy has developed as a method for investigating dielectric and transient photoconductive characteristics of materials over the past few decades. Since it can measure electrical resistance without touching the sample and has a temporal precision of a few picoseconds. Due to the low energy of THz radiation and the narrow pulse width, THz-TDS technology is non-destructive when used for extracting visual data from materials (picosecond range). This paper reveals optical parameters extraction methods by using THz transmission spectroscopy technology. In summation, materials with a low absorption of terahertz radiation can benefit from the adaptability of transmission methods, while materials with a high absorption capacity can take advantage of the advantages of reflection methods. To measure the magnetic material's optical properties like refractive index and absorption coefficient, we employ a transmission-type terahertz time domain spectroscopic instrument. The observations and analysis are performed in both the time domain and frequency domain, and we examine the transmission of terahertz radiation through a polymer based magnetic nanoparticle substance at frequencies from 0.1 to 3 terahertz (THz). In the past few years, magnetic materials based on frequency selective surfaces (FSS) have become indispensable in the design of gigahertz (GHz) and terahertz (THz) millimeter-wave filters, polarizers, absorbers, EMI shielding, antenna reflectors, and radar applications. In this research, ferrite was used to produce a microstructured FSS on a quartz substrate. Frequency Domain (FD) solvers included in the CST MWS commercial software package, which is based on the Finite Integration Technique (FIT), are used to evaluate the FSS's efficiency. Here, we demonstrate a terahertz filter made from arrays of circular holes in a quartz substrate, which acts as a frequency selective surface (FSS). We shall show the properties of FSS terahertz-wave transmission using a finite difference time-domain approach. Researchers looked examined the suggested design over a range of frequencies from 0.2 THz to 3 THz. The proposed structure's complementary behaviour is also statistically analysed. We evaluate the proposed layouts by investigating their most elemental characteristics, such as their transmittance and polarisation. The response of the proposed structure to a broad variety of incidence angles is also investigated. Additionally, at the frequency selective surface of the magnetic material, polarisation insensitivity is achieved for the TE and TM stimulated mode. This research presents the detailed layout and analyses of the evaluated parameters for the proposed terahertz wave filter. The suggested terahertz wave filter's parameters are then fine-tuned. The filter we describe has the potential to be widely used in future terahertz wave systems due to its low manufacturing costs and simple design.