Active Phased Array Radar Signal Design And LPI Performance Research

Since the emergence of the active phased array radar, it is widely used in a numberof areas, especially in ground and airborne warning system. This new radar system has aseparate transceiver components, and the use of computer-controlled antenna beamforming can achieve instantaneous scanning a wide range, compared to the traditionalsystem of radar antenna has a higher flexibility. With the development of signaldetection and interception technology and the performance improvement of ESMreceivers, the electromagnetic environment gets more complex, which puts forwardhigher requirements on survivability of the radar which is at the frontier of electroniccountermeasures. The radar must detect the ESM receiver before itself being detected,in order to established advantages in the electronic countermeasures. In this context, theconcept of LPI (low probability of intercept) radar is promoted and soon becomes aresearch hotspot in new radar system field. LPI radar is difficult to be detected by meansof intercept receiver because of its frequency variability, wide bandwidth, low peakpower and other design attributes, thus avoiding the active interference, Anti-radiationmissile and other threats, which means it has a strong stealth. This paper studies the LPIradar signal design in the active phased array radar system, not only to improve theviability of airborne radar equipment, but also a useful attempt to explore how could thetwo new radar system organically combined.The work includes four aspects:1. LPI radar theory, signal design and signalambiguity function are studied. Two basic waveform design method and the main typesof radar ambiguity function are discussed. Summarizes the main features of the lowprobability of intercept signal;2. Analyzes types of signals that include common singlemodulation and hybrid modulated signals, through ambiguity function modeling andsimulation, and then determine hybrid modulated signals, as the focus of the researchdirection.3. A new method of staggered hybrid modulated signal is proposed, and itssignal construction and ambiguity function are deduced and analyzed. The result ofsimulation shows that the new signal has an ambiguity function close to the ideal“thumbtack” shape, which means it has a good performance on distance and velocity resolution.;4. Simulation and calculate the peak power of the signal and interceptionfactor relative value base on the radar intercepted factor theory, and then two methodsof time-frequency analysis–WVD and SPWVD are used to analyze the LPIperformance of the signal, and then compared with several single modulation signal andBarker-LFM hybrid modulated signal. The result shows this new type of signal has abetter ability to resist interception against the signal detection method based on thetime-frequency analysis.