## 3 Results and Discussion  
The simulation and modeling of the proposed antenna are done using a commercially available CST Microwave studio. A prototype of the final EBG loaded design is fabricated and tested. The S-parameter is measured using a performance network analyzer (PNA) series vector network analyzer (E8362C 10 MHz-67 GHz) and the radiation characteristics, efficiency, and realized gain are measured using a Satimo Star-Lab near-field antenna measurement system. The photography of the fabricated prototype and its Satimo setup is shown in Figures 13 and 14, respectively. The measurement begins with the placement of the antenna under test (AUT) in the middle of a circular arc on the test bed which consists of 16 separate receiving antennae as shown in Figure 14. This system measures the radiated power of the antenna in the near field region for computing the far field values of the AUT. The receiving antennae are spread out evenly across the arch. To get the 3D radiation pattern, the creation of a full 3D scan which has been done by rotating the AUT horizontally by 360 degrees is required [31]. The S-parameters of the final patch antenna with the EBG loaded and without the EBG is given in Figure 15. It has been found that because of the DGS structure, the bandwidth of the final proposed antenna increased. The efficiencies and realized gains of the desired passband frequencies are also increased which are shown in Figure 16,b respectively. The measured data is in good agreement with the simulated result except for the result of the efficiency. This is because of the fabrication tolerance and also some small defects which were introduced during the soldering of the subminiature version A (SMA) connector which cannot be seen in Figure 13. Moreover, the loss of the radio frequency (RF) feeding cable is not considered during the simulation. A comparison between the different parameters of the present work and some previous work are given in Table 2. Though the antenna is bigger than other designs mentioned in the Table, it gives a wider bandwidth with better impedance matching that is one of the important requirements of 5G. Another important fact should be noted that implementing DGS in the ground plane shifts the passband frequency slightly to the lower side and results in a gain reduction. This may be due to the increased bandwidth because the relation between the gain and bandwidth are reciprocal to each other or it may be due to the resonating property of the DGS slots which is a common problem of this technique and has also been observed in previous research work [9]. Figure 14: Satimo setup of the fabricated prototype. Figure 13: A fabricated prototype of the proposed antenna (**a**) The front side; (**b**) The back side. The radiation patterns in the YZ-plane and XZ-plane for the lower passband and upper passband frequencies with and without DGS (only YZ-plane) are shown in Figures 17 and 18, respectively. From the radiation pattern in the YZ-plane, it can be observed that the EBG structure influences the patterns in the backward direction for both passband frequencies. This is because the slots in the ground plane are itself resonators and in the high-frequency region the effect is worse, which is clear from the current distribution plot of the ground shown in Figure 19.  
Figure 16: Comparison between EBG and non-EBG configurations. (**a**) Efficiency; (**b**) Realized gain. Figure 17: The radiation patterns in the YZ-plane. (**a**) 3.532 GHz, 3.736 GHz (no_DGS); (**b**) 6.835 GHz, 6.074 GHz (no_DGS). Figure 15: Comparison of the S-parameters of the EBG and Non-EBG configurations. That's why a notch has been formed in the pattern of the higher passband frequency after implementing the EBG structure which was not present earlier. However, the radiation patterns are not in the same direction which is a common problem of the patch antenna.