# Design of Triple-Band (DSRC, 5G, 6G) Antenna for Autonomous Vehicle Telematics
## 4 Antenna Fabrication and Measured Results  
Figure 15 shows the fabricated dual-band DSRC+5G antenna array constructed according to the specifications in Table 1 and designs in Figures 1 and 2. The top two-by-two 5G inset-fed patch array and bottom DSRC patch antenna were built using an in-house precision milling machine (LPKF ProtoMat S62 and ProtoLaser S). The 2.92 mm SMA connectors from Southwest Microwave (1012-16 SF and 1092-03A-6) were used for both port I (5G) and II (DSRC), respectively. A vector network analyzer (VNA: Agilent E8361C PNA) was used to characterize S-parameters of the fabricated dual-band antenna. The VNA can measure from 10 MHz to 67 GHz with 94 dB of dynamic range. We measured the radiation patterns at the DSRC frequency bands in an anechoic chamber (Raymond EMC Quietbox AVS 700) and the radiation patterns at the 5G frequency bands in an anechoic chamber from the Antenna Test Lab Company. Because there is no Rogers RT/duroid 5880 substrate thickness of 0.051 mm, the developed 6G eight-by-eight antenna array was not fabricated. When such a substrate  
Figure 14: (**a**) S-parameter and (**b**) realized gain at boresight of eight-by-eight array with or without power divider and CPW to MS transition. Figure 15: Fabricated dual-band DSRC+5G stacked patch antenna: (**a**) Top view and (**b**) in anechoic chamber. is available, the 6G antenna array will be fabricated using photolithography via plasma etching instead of the precision milling machine. Figure 16 shows the simulated and measured S-parameter of the developed antenna. As shown in Figure 1, ports 1, 2, and 3 are for 5G, DSRC, and 6G frequency bands, respectively. The measured results show a reasonably good agreement with the simulated results. The simulated 10 dB impedance bandwidths are 0.11 GHz (5.85-5.96 GHz) for the lowest DSRC frequency band, 1.17 GHz (27.62-28.79 GHz) for the middle 5G frequency band, and 14.81 GHz (131.91-137.56 GHz, 140.53-146.87 GHz, and 153.06-155.88 GHz) for the highest 6G frequency band. The measured 10 dB impedance bandwidths are 0.12 GHz (5.85-5.97 GHz) for the lowest DSRC frequency band and 0.9 GHz (27.6-28.5 GHz) for the middle 5G frequency band. Further, it is noted that the simulated S\({}_{21}\) shows values 5 to 20 dB higher than the measured S\({}_{21}\). This is mainly attributed to the introduction of the 6G antenna array. Compared to the simulated S\({}_{21}\) reported in our previous paper [7], the simulated S\({}_{21}\) in Figure 16 shows a higher S\({}_{21}\). Figure 17 shows the peak realized gain at the boresight of the developed triple-frequency antenna. The simulated peak realized gain ranges from 6.74 to 6.87 dBi at the DSRC frequency band, 9.1 to 12.3 dBi at the 5G frequency band, and 15.1 to 19.8 dBi at the 6G frequency band. The measured peak realized gain at boresight is 5-6 dBi at the DSRC frequency and 10.1-12 dBi at the 5G frequency band. A slight difference between the simulated and measured results is mainly attributed to the minor effects from the SMA connector and soldering, non-uniform substrate thickness from mechanical drill bits (10-20 \(\upmu\)m), and fabrication imperfection. The simulated and measured E-plane normalized radiation patterns of the designed antenna at 5.9 GHz, 28 GHz, and 154.5 GHz are shown in Figure 18. Broadside radiation  
Figure 16: S-parameter of the developed triple-band antenna array. Figure 17: Simulated and measured frequency-dependent peak realized gain at the boresight. patterns with 20 dB or higher front-to-back ratios are observed. Further, \(-15\) dB of cross-polarization levels at the boresight are also observed at all frequencies, indicating directional radiation desirable for telematics applications. Table 2 summarizes the antenna performance of recently reported DSRC, 5G, and 6G antennas with our designed triple-band stacked patch antenna. The proposed antenna has a high peak realized gain at DSRC, 5G, and 6G bands with a simple structure for easy fabrication.