# A Subcell Finite-Difference Time-Domain Implementation for Narrow Slots on Conductive Panels
## 4 Results
### Enclosure under Plane Wave Incidence  
In this test case, we evaluated the SE of a rectangular PEC cavity with dimensions \(300\,\mathrm{mm}\times 300\,\mathrm{mm}\times 120\,\mathrm{mm}\). The cavity has a \(100\,\mathrm{mm}\times 5\,\mathrm{mm}\) slot on one of its rectangular faces, which can be either PEC or made of a CFC material. For the CFC case, we use a SGBC numerical model with an equivalent conductivity of \(200\,\mathrm{S/m}\) and a thickness of \(1\,\mathrm{mm}\). The cavity is illuminated with a non-normal plane wave at an angle of \(45^{\circ}\) (see Figure 7). Figure 5: Dipole in front of a narrow slot on an indefinite conductive plane panel. The SE is evaluated at the center point of the cavity for both the electric fields \(\mathrm{SE_{ee}}\) and the magnetic field \(\mathrm{SE_{hh}}\),  
\[\mathrm{SE_{ee}}=20\log\frac{\left|\vec{E}_{\mathrm{PW}}\right|}{\left|\vec{E}_ {0}\right|},\ \ \mathrm{SE_{hh}}=20\log\frac{\left|\vec{E}_{\mathrm{PW}}\right|}{\eta_{0} \left|\vec{H}_{0}\right|} \tag{3}\]  
where \(\vec{E}_{0}\) and \(\vec{H}_{0}\) are the electric and magnetic fields evaluated in free space at a location coinciding with the center of the original cavity, \(\vec{E}_{\mathrm{PW}}\) is the field generated by the plane wave, and \(\eta_{0}\) is the intrinsic impedance of free space. Several setups for the cage are compared: a slot on the PEC cover, a slot on the conductive panel cover, an open box (without conductive panel), and a conductive panel without a slot. The aim is to compare and understand the contributions of each of the different propagation ways. We also include an analytical formulation of the slot on the PEC panel given in ref. [26]. The SE behavior of an enclosed entity can be determined by three main variables: the size of the object, the presence of any apertures, and the conductivity properties of its wall materials. Two regions can be considered for each: LF and high frequency HF. The SE behavior is a function of a combination of the three variables mentioned above, thereby delineating distinct regions. The proposed cage, which includes a conductive panel and slot, exhibits three distinct regions. At LF, before the cutoff frequency of the slot and the cage, the \(\mathrm{SE_{ee}}\) is characterized  
Figure 6: Comparison of the IL results of CA and DMMA methods for a narrow slot on a conductive indefinite plane. Figure 7: Geometry of a rectangular PEC cavity with slot mounted on conductive face. The slot dimensions are \(100\,\mathrm{mm}\times 5\,\mathrm{mm}\). by an attenuation of \(-20\,\)dB, while SE\({}_{\text{hh}}\) remains constant (assuming that the cage is made using electrically conductive materials for its walls). In this region, the dominant factor influencing both SE is the largest opening in the cage, determined by the size of the conductive panel, as depicted in Figures 8 and 9. The trend is similar to the \"open box\" curve (without a conductive panel). At medium frequencies (MF), currents start to be induced around the openings following [PERSON]'s law. This inductive behavior results in an increase of SE with a slope of \(+20\,\)dB per decade in the LF region. Consequently, the SE\({}_{\text{ee}}\) remains constant, while the SE\({}_{\text{hh}}\) experiences a gain of \(+20\,\)dB. The resonant zone occurs at HF where the slot size becomes comparable to the wavelength. In this regime, the finite conductivity of the material does not have any influence, and the resonances are determined by both the slot and the cage size. In this case, no significant differences between DMMA and CA are found in Figures 8 and 9, even at HF, in the resonant zone. We attribute this agreement to the accurate prediction of cavity resonances by all methods, which dominate the errors introduced by the resonances of the slot. Figure 8: Electric field shielding effectiveness (SE\({}_{\text{ee}}\)) evaluated at the central position of the rectangular enclosure.