###### Abstract  
This study examines the electromagnetic properties of a composite material composed of iron pyrite (FeS\({}_{2}\)) and epoxy resin, mixed in a 3:2 weight ratio to create a 10 cm\({}^{3}\) cube. The research analyzes transmission and reflection coefficients and band gap parameters to determine its viability as an antenna substrate for electromagnetic wave applications. The composite displays a tunable band gap of 1.3 eV, enabling selective absorption and emission of electromagnetic radiation. The transmission coefficient achieved 90% throughout a frequency range of 1 GHz to 15 GHz, whilst the reflection coefficient was measured at 10%, significantly reducing reflecting losses. The epoxy resin binder was essential for preserving structural integrity and augmenting the dielectric characteristics of the composite, thereby raising transmission efficiency. UV-Vis spectroscopy showed an absorption value of 0.875% at the band gap, indicating efficient interaction with UV energy. The S21 transmission coefficient ranged from \(-\)10 dB to \(-\)80 dB, with a maximum of \(-\)40 dB at 6 GHz, indicating strong energy transfer capability for antenna applications. The S21 values exhibited negligible signal attenuation between 2 GHz and 7 GHz, indicating the material's exceptional suitability for antenna substrates necessitating dependable transmission. The S11 reflection coefficient varied from \(-\)5 dB to \(-\)55 dB, with substantial decreases between 4 GHz and 14 GHz, when reflection decreased to \(-\)45 dB, signifying little signal reflection at essential frequencies. The results underscore the composite's appropriateness for applications requiring high transmission efficiency, little reflection, and effective engagement with electromagnetic waves, especially as an antenna substrate. Measurements were performed using a vector network analyzer (VNA) to obtain the S11 and S21 characteristics, underscoring the material's potential in sophisticated electromagnetic applications. electromagnetic wave transmission; iron pyrite composite; tunable band gap; UV spectroscopy absorption +
Footnote †: journal: materials  
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Footnote 0: 0  
the substrate material is a critical component influencing antenna performance [2]. The dielectric constant dictates the interaction between the substrate material and the antenna's electric field. A substrate with a high dielectric constant may provide a reduced antenna size, advantageous for high-frequency applications when spatial constraints are present [3]. A high dielectric constant lowers the wavelength of electromagnetic waves in the substrate, enabling a more compact antenna construction without compromising performance. In contrast, substrates with a decreased dielectric constant are often used to attain a broader bandwidth and enhanced performance at lower frequencies [4]. The dielectric qualities of the substrate material are essential for maximizing the antenna's operating frequency and overall efficiency. Substrate materials used in antenna design have unique benefits and drawbacks, influencing the antenna's performance and appropriateness for diverse applications [5]. Rogers materials, such as RO 3210 and RO 4003, are recognized for their high dielectric constants and superior signal integrity, making them particularly suitable for high-frequency applications. These substrates are engineered for stability and minimal loss properties, allowing antennas to operate reliably at elevated frequencies, which is essential for applications demanding accuracy and consistency. Specifically designed by Rogers Corporation for use in printed circuit boards (PCBs) and microwave circuits, these high-performance substrates facilitate the downsizing of antennas and circuits without compromising performance--an essential feature in modern high-frequency communication systems that require compact designs. The elevated dielectric constant of Rogers materials not only enables miniaturization but also ensures superior signal integrity, minimizing signal loss and distortion.