## 4 Detection Performance and Discussion
### Experimental Setup  
A series of experiments were conducted at the Institute of Electronics, Chinese Academy of Sciences in Beijing and the China National Fire Equipment Quality Supervision Centre in Shanghai. The experimental setup is shown in Figure 11.  
The first experiment was performed outdoors at the Institute of Electronics, Chinese Academy of Sciences, with a male human subject as shown in Figure 11b. The subject stood behind the wall at distances of 300 cm, 600 cm, 900 cm, and 1100 cm from the radar facing the antenna. Disaster victims  
Figure 11: The experimental setup for data acquisition, (**a**) the experiment model, (**b**) through-wall detection outdoors, (**c**) the azimuth angle experiment, (**d**) through-wall detection indoors, and (**e**) the actuator experiment.  
are typically buried in rubble composed of different building materials, so the wall consists of three common building materials, 30 cm of brick, 35 cm of concrete, and 35 cm of wood, for a total thickness of 1 m. The radar was installed on a table 150 cm above ground. The detection performance with the steps before the FFT as discussed previously were obtained using the outdoor experimental data for a female subject behind the wall facing the antenna at a distance of 600 cm from the antenna in Section 4.2, and Sections 4.3 and 4.4 analyzed the detection results using the developed method based on the data acquired in this experiment.  
The second experiment was carried out indoors with a different human subject standing behind the wall at distances of 700 cm and 1000 cm facing the antenna at the China National Fire Equipment Quality Supervision Center as shown in Figure 11d. The detection results using the data acquired in this experiment were given in Section 4.3 to validate the detection performance of the proposed algorithm.  
In the third experiment, a male human subject stood at angles of 0\({}^{\circ}\), 30\({}^{\circ}\) and 45\({}^{\circ}\) with respect to the antenna at the Institute of Electronics, Chinese Academy of Sciences, as shown in Figure 11c. The distance between the subject and antenna is 1100 cm, and the beam angle is 60\({}^{\circ}\). Section 4.5 showed the influence of the azimuth angle between the subject and antenna on the detection performance.  
The fourth experiment was carried out indoors at the China National Fire Equipment Quality Supervision Center using the actuator shown in Figure 11e to imitate human respiration. The actuator was placed on a desk 130 m above ground with a distance between the actuator and antenna of 400 cm and 700 cm. The fifth experiment was carried out outdoors at the Institute of Electronics, Chinese Academy of Sciences, using the actuator to imitate human respiration. The actuator was placed on a desk 130 cm above ground with a distance between the actuator and antenna of 1100 cm. The performance of the developed algorithm is validated using these data acquired from the actuator as shown in Section 4.6.  
In the sixth experiment, six human subjects (four males and two females) were employed to acquire data using the outdoor setup. All subjects stood facing the antenna at distances of 300 cm, 600 cm, 900 cm, and 1100 cm from the wall. Three datasets were obtained for each subject and distance for a total of 72 datasets. All these datasets are used to determine if a human is present in the detection environment as in Section 4.7.