As one of the most widely-used methods for target detection and recognition, the radar has been intensively studied since it was proposed. In the past few decades, great efforts were devoted to improve radar's functionality, high precision and real-time performance, of which the key is to generate, control and process a wideband signal with a high speed. However, due to the well-known "electronic bottleneck", it is extremely difficult for electrical systems to handle a signal with a high frequency and large bandwidth. The optical technologies, with the intrinsic characteristics of high frequency, large bandwidth, low loss transmission and electromagnetic immunity, were considered as the keys to "illuminate the future of radar". In addition, photonic systems are light, small and integratable, which would significantly reduce the load of aircraft, satellites and ships when carrying the radar. Therefore, photonic technologies would change the existing radar systems, making radar systems more sustainable. In this paper, an overview of the microwave photonic radars is presented. The recent progresses of the key technologies and the future developments of the microwave photonic radars are discussed.

microwave photonics radar  /  signal generation  /  signal processing  /  beamforming