In recent years, the high demand for broader bandwidths, high data transmission and reception rates at low power in the wireless communication has motivated the development of systems operating at high frequencies, such as THz band. It has been implemented mainly in indoors mobile communications systems, where is necessary to miniaturize devices, such as filters and antennas. Nonetheless, devices miniaturization problems are commons especially on their performance (Song and Tadao, 2011 and Akyildiz et al., 2014).
Patch antennas operating in the THz band have been used to solve most of the devices miniaturization problems. However, parameters such as bandwidth, gain and directivity present low performance due to surface waves caused mainly by substrate thickness. The antenna bandwidth decreases when the substrate thickness is relatively thin, however, when the substrate thickness is substantially thick the bandwidth increases, and also, increasing the losses by surface waves (Chang and Richards, 1986; Vandenbosch and Van de Capelle, 1994).
Graphene-based microstrip antennas with PBG substrate (Photonic Band Gap) are considered important candidates to solve the problems described above, besides generating TE and TM band regions, it increases the antenna bandwidth and efficiency with the correct arrangement of the periodic lattice (Boutayeb and Denidni, 2007; Mosallaei, and Rahmat-Samii, 2003; Joannopoulos et al., 2011; Miranda et al., 2020; Miranda et al., 2021 and Sousa et al., 2020). Considering the above, we propose in this paper a new graphene patch antenna with a triangular lattice of air holes PBG substrate operating in the THz band. Thus, the antenna radiation characteristics shows a significant improvement due to the use of PBG substrate for the patch antenna based on graphene.13
Bala and Marwaha (2015a and 2015b) present two antennas, a triangular GNPA operating in the range of 1 to 3 THz, which achieved a good combination of impedance in resonance frequencies with 5.6% of bandwidth, and another GNPA rectangle operating at a resonance frequency of 2.9 THz where they compare the results of five different substrates (hardwood, polyamide, quartz, silica and silicon). Thampy et al. (2015) point out that recent advances in the synthesis and characterization of graphene films indicate that this material is suitable for photoelectronic applications, and also, has optimum electrical and optical characteristics for nano-antenna systems that radiate in the THz band.
George and Madhan (2017), proposed a microstrip antenna design, using as a patch, a very thin layer of graphene on a silica substrate with variable thickness, with the heights of 30, 33 and 37.5 µm only one transmission band was obtained, already for the heights of 43, 44 and 45 µm were obtained two transmission bands, these results were analyzed in terms of S11, gain, efficiency and bandwidth. Oliveira et al. (2018) modeled and simulated a microstrip antenna with a ceramic substrate of BiNbO4 doped with V2O5 in an air hole network using Ansys HFSS software. Parameters such as S11, radiation pattern, gain and directivity were analyzed, where they observed an improvement in performance when compared to antennas using non-ceramic substrates or with ceramics without periodic network. They stated that these ceramic antennas offer significant advantages in terms of compactness, weight, thermal stability, low production cost and they can also be used in microwave integrated circuits.
Recently Benlakehal et al. (2022), designed and analyzed an array of 2×2 microstrip patch antennas based on different substrates, including periodic, non-periodic and homogeneous photonic crystals, through the use of two different simulation techniques, CST Microwave Studio software based on the technique of finite integration and Ansys HFSS software based on the finite element technique. According to the researchers, these antennas could be applied in sensing and communication technologies, in this sense the set of antennas designed based on periodic photonic crystals had a better performance than the set of conventional antennas in terms of S11, bandwidth, VSWR, gain and radiation efficiency around 0.65 THz, however, these same parameters were considerably improved using non-periodic photonic crystal substrate.
Here we designed and simulated a numerical investigation by Ansys HFSS of a graphene-based GNPA with periodic triangular arrays of holes in the substrate in the SiO2 substrate with different heights. The proposed antenna was designed for applications in the THz band. This paper is organized as follows: In Section 2 discusses the design of the GNPA. Section 3 presents the results and simulations. Parameters such as reflection parameter (S11), radiation pattern, gain, directivity, bandwidth and efficiency were analyzed. We proposed an innovative GNPA with a triangular lattice that allows double band operation. And finally in section 4 the conclusions are made and in section 5 the references.