## 2 Electromagnetic Field  
Figure 1 presents a simplified illustration of how a microwave field might look inside an apartment, which is part of a residential building (on the right), opposite a transmitter--a base station of a mobile telecommunications network (on the left). In this diagram, only one source is shown, and the radiation is, therefore, emanating from a single direction. However, most base stations have multiple antennas emitting in various directions. Additionally, there could be multiple sources of microwaves around the building, such as several base stations, television transmitters, etc. Therefore, microwaves impact the building from various sides and at different angles [9; 10; 11]. Figure 1: Microwave radiation in a residential building. In cases where transmitters are mounted on the roof of a building, individuals on the topmost floors will be exposed to an electromagnetic field. This field will be weaker than if the transmitters were on an adjacent building. However, since most antennas of base stations have a certain directional characteristic, a number of \"hot spots\"--areas with significantly higher field intensity than the intensity of the direct wave or the average intensity--can occur in a relatively small area. Hot spots can occur inside the building but also outside [12; 13; 14]. As years pass, we are witnessing an imperceptible expansion and increase in technical sources of electromagnetic fields and, thus, the development of wireless information technologies. Currently, there is significant attention on the newly established 5G network, which is receiving considerable support. On one hand, this is a great benefit for us, but on the other hand, the increase in electromagnetic fields also brings certain negatives. We are in daily contact with electrical devices that generate electromagnetic fields (EMF). Therefore, it is good to be aware of their harmful effects on our body and also know how to protect ourselves from such fields. For these reasons, it is important to study electromagnetic fields. The most common method of studying them is by modeling these fields using various computer programs capable of simulating the passage of such fields through different materials and then reliably analyzing them. An electromagnetic field is a field composed of two components: an electric component and a magnetic component. The electric field exists wherever there is some form of electrical energy. It is created by the presence of electrically charged particles in electrical devices, whether or not current is flowing through them. The magnetic field is characterized by the fact that it only arises where there is a flow of electric current. The electric field is defined as follows [12; 15; 16]:  
* By the vector of electric induction \(D\). * By the vector of electric field intensity \(E\). As mentioned, a magnetic field is created by the movement of charged particles, more precisely, by the movement of electrons in a conductor, for example, a regular cable. The movement of these electrons through the cable generates an electric current. The larger this current, the larger the size of the magnetic field, but its size decreases with increasing distance from the source of energy. Like the electric field, it is defined by two vectors [16; 17]:  
* The vector of magnetic induction \(B\) with the unit T.
* The vector of magnetic field intensity \(H\) with the unit A/m. By combining these two fields, i.e., the electric and magnetic fields, we obtain an electromagnetic field, and its components are perpendicular to each other. In terms of frequency, it contains all components of electromagnetic energy, including radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma radiation.