## 4 System Performance Discussion
### Parameter Discussion on System Performance
#### 4.2.5 Dynamic Range  
The introduction of insertion loss will also affect another important performance index of the radar system, the dynamic range. Within this range, the radar receiver will not be distorted due to the excessive amplitude of the received signal or not be detected because the receiving signal is too small.  
\[D=10\lg\frac{P_{\max}}{P_{\min}} \tag{31}\]  
\(P_{max}\) and \(P_{min}\) are the upper limit and lower limit of the receiving signal amplitude, respectively. In order to make sure the system is working under the linear area of the receiver, the transmitter has to consume more energy, which reduces the efficiency of the single RF link MIMO radar system. Meanwhile, the introduction of insertion loss will theoretically increase and lead to the decrease of dynamic range. Therefore, for the single RF link MIMO radar, the insertion loss introduced by the newly added SPDT switch will greatly affect the performance of the radar. In order to work properly, it is very important to adopt an SPDT switch with small loss.  
In order to reduce the impact of insertion loss, it is necessary to first detect the normal working state of each part of the system to prevent unnecessary loss due to the internal problems of the system. Secondly, the elements with low insertion loss can be selected. If the switch is not available, the gain of the transmitter amplifier can be properly increased to a certain range to compensate for the loss of the signal energy caused by the insertion loss. In this system, the gain of the transmitter amplifier is 10. In order to explore the influence of amplifier gain on the detection probability of the target, the initial insertion loss was set to 3 dB to make the results more obvious. Under the conditions listed in Table 3, 1000 groups of experiments for each gain were carried out to get the detection probability, as is shown in Figure 14.  
From this result, we can see that detection probability increases with the increase of transmitter amplifier gain. When the power amplifier multiplier is 11.5, the detection probability has risen from the lowest value of 96.8% to 99.5%. When the power amplifier multiple is 13, the detection probability is very close to 1. The result indicates that it is feasible to compensate for the insertion loss introduced by the new SPDT switch by improving the gain of the power amplifier at the transmitter side. The physical properties, such as power and capacity of switches and other components, have not been taken into  
Figure 14: The relationship between the gain and the detection probability.  
consideration. Under the actual working conditions of radar, the choice of power amplifier needs to be varied according to the performance of internal physical components.  
To sum up, in order to achieve higher performance of the single RF link MIMO radar system, the switching time, isolation, and insertion loss of the insertion switch should meet the requirements of the real condition. In theory, if we choose an SPDT switch with excellent performance, we can solve the above problems. Some parameters can be corrected according to the relationship between the performance and parameters of the MIMO radar and the precision of the radar system.