## 4 Measured Results and Discussion  
To evaluate the proposed design, the model of the absorber is manufactured and measured. The Prototype of the absorber consists of 10 \(\times\) 10 elements and the total size of the absorber is \(237\times 237\) mm\({}^{2}\). The dielectric resonator is printed using the commercial 3D printer, MakerBot Replicator 2X, based on FDM technology. Limited by the printing size of the 3D printer, the absorber is divided into 2 \(\times\) 2 substructures, and each substructure consist of 5 \(\times\) 5 elements. In the printing process, the temperature of the nozzle is set at 230 \({}^{\circ}\)C, and the bed temperature is set at 110 \({}^{\circ}\)C. The nozzle of the printer has a diameter of 0.4 mm, and the thickness of each layer in the z-axis is set as 0.1 mm, which is the same as that for printing the cube sample. The total time of the printing process is about 24 h. The weight density of the absorber is about 0.55 g/cm\({}^{2}\), making it suitable for  
Figure 4: Simulated vector field distribution in the absorber. (**a**,**c**,**e**,**g**) \(E\)-field in _xoz_ plane for \(f_{1}\),\(f_{2}\),\(f_{3}\), and \(f_{4}\) of 4.41, 6.24, 8.61 and 10.76 GHz, respectively. (**b**,**d**,**f**,**h**) \(H\)-field in _yoz_ plane for \(f_{1}\),\(f_{2}\),\(f_{3}\), and \(f_{4}\) of 4.41, 6.24, 8.61 and 10.76 GHz, respectively. (**i**,**j**,**k**,**l**) Power loss density of the resonator in _yoz_ plane for \(f_{1}\),\(f_{2}\),\(f_{3}\), and \(f_{4}\) of 4.41, 6.24, 8.61 and 10.76 GHz, respectively. the applications requiring low weight. After the dielectric resonator is printed, a copper foil with a thickness of about 0.1 mm is attached to the back side of the dielectric plate, acting as the metal plate, as shown in Figure 5b. The absorptivity is calculated using the reflection coefficient of the absorber, which is measured using two broadband horn antennas connected to the VNA. To eliminate the effect of the propagation path, the reflection coefficient of a metal plate with the same size as the absorber is also measured and used as a reference. The reflection coefficient of the absorber is normalized to that of the metal plate. The measured results of the absorber are shown in Figure 5c, and the simulated ones are also plotted for comparison. There is a good agreement between the simulation and measurement, and the absorption is higher than 90% in the whole band of interest. There are some variations between simulated and measured results, which may be caused by the imperfections arising from the fabrication process and measurement process. One thing that should be noted is that the incident angle corresponding to Figure 5 is 0\({}^{\circ}\). The absorptivities corresponding to the EM waves with different modes and different incident angles are quite crucial for evaluating the performance of the absorber and are also simulated and discussed. The simulated absorptivity of the absorber under different incident angles for transverse electric (TE) mode and transverse magnetic (TM) mode is shown in Figure 6. The incident angles vary from 0\({}^{\circ}\) to 45\({}^{\circ}\). From the figure, we can see that in both the TE and TM modes, the absorptivity remains at a high level and the absorption is higher than 90% in most of the band of interest. For the TE mode, when the incident angle increases, the absorption at the lower band decreases, while the absorptivity remains at a high level at the higher frequency band. In the whole band of interest, the absorptivity is higher than 83%. For the TM mode, when the incident angle increases, there is also a decreasing trend that can be found in the absorptivity. However, this trend is inconspicuous compared with that for the TE mode. The absorptivity is higher than 88% in the whole band of interest, indicating that the  
Figure 5: Photo of prototype of the designed absorber. (**a**) Top side; (**b**) Bottom side; (**c**) Simulated and measured absorption spectra of the proposed absorber. absorber performs well over a wide range of angles of incidence.