## 1 Introduction
Considering all these parameters, graphene was used as a conductive material to produce the antenna suitable for the desired target both at an affordable cost and in the desired bandwidth, and a 3D printer was used as the production technique. A traditional microstrip patch antenna has a high-quality factor, leading to some disadvantages related to the narrow bandwidth. Many techniques have been developed to increase the impedance bandwidth, including adopting the known stacked patches [37], parasitic resonators [38], and capacitive coupling feed [39; 40]. It is still challenging to obtain a wider bandwidth, since the main solution uses a thick and/or low dielectric constant substrate. Metamaterial-based absorbers and antennas with different fractal structures are being studied to expand the bandwidth [41; 42]. While studies to increase the bandwidth of antennas are important, it is also very important that antenna production costs are affordable and easy to manufacture. It is known that all conventional antenna manufacturing techniques have disadvantages such as high tool and equipment cost, small volume prototyping, or long lead times for production [43; 44; 45; 46]. The new technologies used for antenna prototyping are laser micromachining and 3D printing technologies. The laser micro-processing technology is a common method that can be used to process many materials such as plastic, glass, and metal and has a versatile process to produce the desired outputs by providing thin foils. This technology includes many mechanisms such as cutting, drilling, marking, turning, and threading. The ability to drill holes at the micron level or make fine cuts is preferred in antenna production as in many areas. Apart from that, this technology presents some problems as it has a thermally induced process. For example, it causes a change in material properties in the heat-affected area, as well as causing thermal stress. In addition, they are economically very expensive and have optical problems. Therefore, laser micromachining technology was not preferred in this study. Recently, the expansion of 3D printing offers new chances for low-cost, fast, and on-demand production of millimeter-wave, microwave, and terahertz (THz) antennas and components [47; 48; 49; 50]. With the rapid development of 3D-printing technology, an alternative solution has been provided, especially for the application of microwave antennas [51; 52]. It offers higher manufacturing accuracy at a lower cost and provides great flexibility in design and production. Therefore, it has many advantages compared to the standard production methods. With 3D printing, the devices can be produced in one piece, and the performance loss caused by combining the parts can be prevented. There are two widely used 3D-printing techniques [53; 54; 55; 56; 57; 58; 59; 60; 61]: polymer/dielectric and all-metal. As the working frequency band enters the millimeter/microwave range, the printed parts' quality for the resulting antenna is of great importance. The print resolution, structural limitations, and surface quality are among the many intangible factors that are hugely important for a functional antenna part. Millimeter-wave/microwaves/THz antennas usually have great details in their geometry, which poses challenging fabrication methods. For all these reasons, it has become attractive to use commercial 3D printers to achieve high spatial resolution, small structure layer thickness, and low surface roughness. Microstrip antennas have become remarkably interesting in that they can be used in many different application areas owing to their wide operating bandwidth and easy adjustment alternatives [62; 63; 64; 65; 66]. Due to advances in handheld electronic devices, these devices need to be thinner to improve performance in small-sized devices [67; 68; 69]. Until now, in the literature, many antenna studies with different designs--the circle [70], ellipse [71], triangle [72], fractal [73], U-shaped [74], etc.