General metasurfaces (MSs) can realize low observability of radar by manipulating the polarization mode and transmission direction of the electromagnetic (EM) waves. Here, we propose the radar trap model to realize EM wave imprisonment. This three-layer model is composed of the transmission polarization converter, the connected dielectric substrate and the reflection polarization converter. Using Jones calculation as a guide, we optimized the geometric parameters of the upper and lower layers to realize specific polarization conversion functions. The middle layer is regarded as the support and matching layer. On this basis, the combined radar trap model can realize the imprisonment of EM waves between upper and lower layers, which is attributed to the cooperative effect of asymmetric transmission and polarization conversion. We further verified the feasibility and correctness of our investigations through two kinds of model designs based on linear and circular polarization conversion mechanisms. Good agreements are observed between simulation and experiment. Even though the design presents a narrow operating bandwidth, it still provides novel ideas for developing radar stealth technology.