# Blind Spot Detection Radar System Design for Safe Driving of Smart Vehicles
## 4 BSD Radar System Design
### System Design  
The antenna design for transmitting and receiving signals in the BSD radar system must meet the conditions specified in Table 6. The antenna design was developed to meet the requirements of the BSD radar system, considering both the 77 GHz and 79 GHz frequency bands. The system was manufactured using the 77 GHz antenna. Table 6 outlines the parameters necessary for designing the antennas utilized in the BSD radar system. The Tx antenna must conform to specific Signal Bandwidth and Antenna Beamwidth metrics, in addition to Antenna Gain and Sidelobe Level. Similarly, the Rx antenna must meet the designated Antenna Beamwidth, Antenna Gain, and Sidelobe Level metrics, as well as Antenna Distance Ratio and VSWR. Figures 10 and 11 show antennas that have been designed to meet the specified antenna performance requirements as outlined in Table 6.  
Figure 10 shows an antenna for signal processing at 77 GHz, which comprises three Tx array antennas and four Rx array antennas. It has been designed with a center frequency of 76.5 GHz. The antenna distance has been designed to be 1.0 \(\lambda\), 0.5 \(\lambda\), and 0.25 \(\lambda\), with the feedline parameters having a length of 2.5 mm for the microstrip line (1.0 \(\lambda\)) and 2.64 mm for the balanced line (1.0 \(\lambda\)). The Rx Balum \(\lambda\) parameters have been designed as follows: Rx1: \(-\)0.5, Rx2: Basis; Rx3: -Basis; and Rx4: \(-\)0.5. The Tx Balun \(\lambda\) parameters have been designed as follows: Tx1 (MRR): 0; Tx2 (SRR1): Basis; and Tx3 (SRR2): \(-\)0.5. The Rx and Tx antenna microstrip lengths and \(\lambda\) have been designed as follows: Rx1: 6.9192 mm (1.5 \(\lambda\)); Rx2: 3.1692 mm (Basis); Rx3: 4.4192 mm (+0.5 \(\lambda\)); and Rx4: 5.6692 mm (+1.0 \(\lambda\)) for the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Antenna Type** & **Parameter** & **Value** & **Remark** \\ \hline \multirow{3}{*}{Tx Antenna} & Signal Bandwidth & 300 MHz & \\  & Antenna Beamwidth (3 dB) & Az. \(\pm\) 40\({}^{\circ}\)/El. \(\pm\) 2.5\({}^{\circ}\) & \\  & Antenna Gain (3 dB) & 15 dBi & \\  & 1 st Sidelobe Level & 20 dBc & \\ \hline \multirow{3}{*}{Rx Antenna} & Antenna Beamwidth (3 dB) & Az. \(\pm\) 40\({}^{\circ}\)/El. \(\pm\) 2.5\({}^{\circ}\) & \\  & Antenna Gain (3 dB) & 15 dBi & \\ \cline{1-1}  & 1 st Sidelobe Level & 20 dBc & \\ \cline{1-1}  & Antenna Distance Ratio & \(d_{12}\): \(d_{13}\) = 1.0:2.5 & \\ \hline \multicolumn{3}{c}{VSWR} & 2.5:1 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Requirements for Antenna Design. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Value** & **Unit** & **Remark** \\ \hline Range Detection & 64.34 & m & Min–Max Range \\ Range Accuracy & 0.5 & m & \\ Range Resolution & 0.5 & m & \\ Velocity Detection & \(\pm\)187 & Km/h & Min–Max Range (\(\pm\)) \\ Velocity Accuracy & 1.46 & Km/h & \\ Velocity Resolution & 1.46 & Km/h & \\ Azimuth Angle (FOV) & Deg. & Min–Max Range (\(\pm\)) \\ Update Time & 25 & msec & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Parameters for BSD Radar System Performance. Rx antennas, and Tx1: 2.7697 mm (+0.5 \(\lambda\)); Tx2: 1.5197 mm (Basis); and Tx3: 5.2697 mm (+1.5 \(\lambda\)) for the Tx antennas. Figure 11 illustrates an antenna for signal processing at 79 GHz, comprising of two Tx array antennas and four Rx array antennas. It has been designed with a center frequency of 78.5 GHz. For the Rx design of the 79 GHz antenna, the microstrip length has been designed as follows: Rx1: 23.6 mm (+9 \(\lambda\)); Rx2: 14.0001 mm (+5 \(\lambda\)); Rx3: 6.8 mm (+2 \(\lambda\)); and Rx4: 2.0 mm (Basis \(\lambda\)). The balanced length has been designed as follows: Rx1: 4.84 mm (1.5 \(\lambda\)); Rx2: 3.56 mm (+1.0 \(\lambda\)); Rx3: 2.28 mm (+0.5 \(\lambda\)); and Rx4: 1.0 mm (Basis). To verify the characteristics of the designed antenna, five items related to the basic characteristics of the antenna were tested. Figures 10 and 11 show the pattern and the results of the designed antenna, respectively.