Single-channel Electronic Tracking Antenna And Low Noise Amplifier

Automatic tracking of targets is one of the primary functions of radar. The monopulse system has several independent channels to receive the target echo signals, and then compares these signals to obtain the target position information in plane. Usually, one-dimensional monopulse system needs two channels, the number in two-dimensional monopulse system is three. Meanwhile, there also need two or three receivers module of consistent performance in the back-end, which has a high back-end design requirement.In this thesis, a novel electronic tracking antenna array is presented. This antenna array is formed by 2X2 microstrip sub-arrays. Through time sequence phase weighting(TSPW) on each sub-array, the amplitude and the phase on each sub-array can be recoved from the output of the resultant single channel. The amplitude and the phase on each array may be used to produce the sum and difference radiation pattern by digital signal processing. As such, compared with the monopulse system, to obtain the tracking signal the RF comparator is eliminated and the number of the receiver channels is reduced from 3 to 1. The prototype for the proof-of-concept has been fabricated and tested. The measured results are given which confirm the correctness and the advantages of the proposed scheme.Furthermore, a HEMT-based X-band low noise amplifier(LNA) is designed. This LNA contains two HEMT field-effect transistors, which is designed in microwave software Ansoft Designer V2.1. The simulation results show that the gain of this cascade LNA is 25dB, and the noise figure is 0.8dB. Meanwhile, the flatness of gain is less than 1dB.