Four-dimensional Antenna Array Theory And Applied Research

With the development of modern radar and communication technology, various electronic systems are putting forward more and more strict requirements on their antennas'performance. Especially in phased array antennas, in order to realize low/ultra-low sidelobes for better spatial filtering characteristics and thus enhancing the received signal characteristics of the radar effectively, the system usually requires a higher precision control on the array antenna's amplitude control components and the phase control components, such as a precise amplitude/phase excitation and a very small error tolerance of various error sources. To realize low/ultra-low sidelobes, conventional phased array antennas usually require the amplitude excitations with large dynamic range ratios. Sometimes, conventional phased array antennas even require their feed network to provide fast beam scanning or shaped beams. These requirements are usually difficult to realize in practical engineering, with a tremendously higher price budget to achieve. Conventional phased array antennas usually are of three dimensional. By introducing a fourth dimension– time– into the conventional phased array antennas, the four-dimensional antenna arrays (4D) can be formed. Due to their additional degree of design freedom, the 4D antenna arrays are capable of realizing low/ultra-low sidelobes or other shaped patterns at very low amplitude ratios or even a uniform excitation. In conjunction with relevant research project, this thesis carries out the research on the realization of software and hardware implementation for the 4D antenna arrays. The thesis mainly contains the following three parts:Firstly, the research background of the 4D antenna array is introduced, including some conventional array classifications, method of pattern synthesis and their advantages and disadvantages, the basic principles of 4D antenna arrays and their classifications.Secondly, based on the theory of 4D antenna arrays, the thesis presents the simulation and experimental results of a 4D antenna array with three typical time schemes, including the Variable Aperture Sizes (VAS) scheme, the Unidirectional Phase Center Motion (UPCM) scheme and the Bidirectional Phase Center Motion (BPCM) scheme. Comparisons among the three schemes are presented, and their advantages and disadvantages are also given.Lastly, considering the mutual coupling effect of the antenna elements in the 4D antenna array, the Differential Evolution (DE) algorithm is used to optimize the the 4D antenna array to produce a mutual coupling compensated shaped pattern. Simulation and measurement results of a -20dB cosec-squared patterns with or without mutual coupling compensation are presented in this thesis, thus confirming the effectiveness of the mutual coupling compensation method for 4D antenna arrays.