In this study, some important parts of a quantum radar are designed using the quantum electrodynamics theory and significantly focused on entanglement conservation. Quantum radar is generally defined as a detection sensor that utilizes the microwave photons like a classical radar and simultaneously employs quantum phenomena to improve detection, identification, and resolution capabilities. However, the entanglement is so fragile, unstable, and difficult to preserve for a long time. Also, more importantly, the entangled states have a tendency to leak away due to the noise. The points mentioned enforces that the entangled states should be carefully studied at each step of the quantum radar detection processes such as the creation of the entangled photons in the tripartite system, the amplification of the photons, the propagation into the atmosphere, and the reflection from the target. At each step, the parameters related to the real mediums and target material can affect the entangled states to leak away easily. The results of simulations indicate that the features of the tripartite system and amplifier are so important to lead the detected photons to remain entangled with the optical modes. Nonetheless, it is found that a lot of entangled photons lose the related non-classical correlation.