## 1 Introduction  
At present, antennas are everywhere, from TV broadcasting and mobile services to biomedical applications and sensors. Due to a lack of space and the continuous decrease in equipment dimensions, the antennas considered to be integrated must be also small and easy to place in tight spaces. That is why planar antennas are highly used in nowadays, and they are shaped to reach the goals of a higher gain and bandwidth while making the dimensions as small as possible. There are a lot of domains in which planar antennas are used, such as biomedical applications [1], wireless local area network (WLAN) applications [2; 3], monitoring changes of the dielectric constant of the atmosphere caused by the presence of pollution [4], microwave sensors to evaluate the dielectric characteristics of different types of materials [5], thermoelectric sensors [6], mapping of terrain, and many others. Almost all the classical antennas have a planar correspondent, and in this case, this paper is considering the analysis of a planar Yagi Uda Antenna [7; 8]. The first Yagi Udaplanar antenna was studied in 1998, but its configuration is improving still in the present studies. These antennas are used in different bandwidths depending on their application, from L-band [9; 10], MICS (Medical Implant Communication System) and ISM (Industrial, Scientific, Medical) 2.4 GHz bands [3; 9; 11; 12; 13], to 5G applications [13; 14] and even terahertz applications. The antenna constructed in this study is operating at a frequency of 2.4 GHz; thus, a short comparison to the other antennas created to be used in the same frequency range is necessary. Table 1 consists of the main characteristics of such antennas from recent studies. The purpose of the present research is an increased gain value and a larger bandwidth for a Yagi Uda planar antenna while maintaining the same small dimensions for the initial structure. There are a lot of ways to increase the gain of an antenna, and some of them like using more layers of substrate, using a certain kind of shape for the patch, using an air gap in the structure or using meta lenses, as mentioned in [15; 16]. In this paper, the purpose of increasing the gain was reached by modifying the geometry of the patch and ground, always evaluating the bandwidth also. With the increasing number of networks, telecommunication manufacturers and operators need to be more careful to protect their staff from radiation hazards. In addition, the military and biomedical applications of the antennas have a major importance due to the proximity of the antenna to the human body. This is why another major concern which is addressed in this study is the influence of the antenna subjected to this study on human tissues. There are a lot of studies regarding this concern. The researchers used the limits imposed by the International Commission on Non-Ionizing Radiation Protection to see how \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Antenna** & **Dimensions** & **Bandwidth** & **Peak Gain** \\  & **(mm \(\times\) mm \(\times\) mm)** & **(\%)** & **(dBi)** \\ \hline
[3] & & \(55\times 48\times 1.6\) & 8\% & 4.34 \\
[8] & & \(76\times 86\) & 53.5\% & 4.65 \\
[9] & & \(100\times 98\times 0.6\) & 7.4\% & 7.09 \\
[13] & & \(68\times 68\times 0.8\) & 15\% & 3.05 \\
[17] & & \(83.63\times 184\times 1.5\) & 28.6\% & 5.7 \\
[18] & & \(42\times 20\times 0.25\) & 13\% & 4.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Similar structures from recent studies with their characteristics. close the antenna can be to the body for the humans to be safe [2; 11; 19; 20; 21; 22; 23; 24; 25; 26; 27]. Reference [28] was used to determine the radiated power density of the antenna; the distance from the antenna where it is safe for a person to be is also determined. It was discovered that for this case, the antenna should be placed further from human tissues due to the exceeded limits of the standards in force. The present study is composed of five main sections.