## 4 Verification of the Measurements from the EMC Topological Model  
In this section, the practical verification of the described EMC topological matrix model is analyzed. The verification was made in situ (in an actual ship's environment) as an example of the possibility of testing a real-life scenario, as shown in Figure 3[14]. In this scenario, the EuT is located in a subspace (the radio station room) surrounded by shielding plane \(S_{2}\) and disturbed by four EM signals, which are as follows:  
Figure 3: The practical scenario for the verification of in situ measurements. * \(E_{1}^{(i)}\) is the ship's own internal disturbing signal, at a frequency of 29.5 MHz, from a radio amplifier surrounded by the shielding plane \(S_{3}\), which is situated under the main deck in the radio station room. The signal propagates to the EuT only via this plane;
* \(E_{1}^{(o)}\) is the first external disturbing signal, which propagates at a frequency of 2 MHz from the transmitting antenna, and is situated above the main deck to the EuT via shielding planes \(S_{1}\) and \(S_{2}\);
* \(E_{2}^{(o)}\) is the second external disturbing signal, which propagates at a frequency of 3025 MHz from the navigation radar antenna to the EuT in a similar way as above, via the shielding planes \(S_{1}\) and \(S_{2}\);
* \(E_{3}^{(o)}\) is the third external disturbing signal, which propagates at a frequency of 9325 MHz from the navigation radar antenna to the EuT in a similar way as above, also via the shielding planes \(S_{1}\) and \(S_{2}\). At first, a theoretical EMC investigation of this scenario by applying the EMC topological model is performed. This requires a calculation of the effective value \(E_{l}^{(t)}\) of the total disturbing signal at the EuT by using Equation (1). Consequently, this requires calculation of both resultant values of the internal and the external disturbing signals, i.e., \(E_{l}^{(i)}\) and \(E_{l}^{(o)}\), respectively, using Equation (2) and Equation (3). In turn, this requires calculation of the components of these signals, i.e., \(E_{l1}^{(i)}\), \(E_{l1}^{(o)}\), \(E_{l2}^{(o)}\), and \(E_{l3}^{(o)}\), by solving Equation (6) and Equation (13). For this, we need to know:  
* the source values of these signals, i.e., \(E_{1}^{(i)}(0)\), \(E_{1}^{(o)}(0)\), \(E_{2}^{(o)}\), and \(E_{3}^{(o)}\);
* the attenuation values of the shielding planes, i.e., \(a_{w31}^{(i)}\), \(a_{w11}^{(o)}\), \(a_{w12}^{(o)}\), \(a_{w13}^{(o)}\), \(a_{w21}^{(o)}\), \(a_{w22}^{(o)}\), and \(a_{w22}^{(o)}\);
* the attenuation values of the disturbing signals in space, i.e., \(a_{s1}^{(i)}\), \(a_{s1}^{(o)}\), \(a_{s2}^{(o)}\), and \(a_{s3}^{(o)}\). The values of the source's disturbing signals were measured during activation of the mentioned sources of EM disturbances. These values were as follows: \(E_{1}^{(i)}(0)=70\) dB\({}_{\rm\mu}\)V/m, \(E_{1}^{(o)}(0)=160\) dB\({}_{\rm\mu}\)V/m, \(E_{2}^{(o)}(0)=154\) dB\({}_{\rm\mu}\)V/m, and \(E_{31}^{(o)}(0)=146\) dB\({}_{\rm\mu}\)V/m. The attenuation characteristics of the shielding planes (walls), \(S_{1}\), \(S_{2}\), and \(S_{3}\), with the points of the attenuation values \(a_{w}\) of the specified shielding planes for the selected frequencies of the marked disturbing signals, are presented in Figure 4. These characteristics are measured for perpendicular orientation of the measuring signal trajectory relative to the plane of the shielding surface. \[E_{1}^{(i)}=E_{l1}^{(i)}=70\) dB\({}_{\rm\mu}\)V/m \(-60\) dB \(-\)\(a_{s1}^{(i)}=10\) dB\({}_{\rm\mu}\)V/m (30)  
The in situ verification tests included measurements of elements of Equation (6) and Equation (13), which are expressed respectively by Equation (30) and Equation (31). The total values of the attenuation \(a_{s}\) of the disturbing signals in the space between their sources and the EuT, taking into account the subspaces between the shielding planes, are calculated.