The Study Of Transient Beamforming Array With Ultra-wideband Antennas

With the development of modern radar technology, the focus of research hasshifted to how to improve the range resolution and the performance of target recognitionimaging. How to increase radar invisibility and anti-jamming capability is also take intoaccount. Ultra-wideband technologies attract widely attention in radar targetidentification, imaging, anti-stealth and short-distance communication. As an importantpart of the ultra-wideband radar, the performance of time-domain UWB antenna arrayplays a decisive role for ultra-wideband radar.This thesis focuses on design of UWB antenna/array and transient beamformingtechnology. On the basis of analysis of synthesis wave, radiate principle and beamscanning theory, time domain/frequency domain performance and beamformingcharacterization of ultra-wideband antenna array are proposed:1. The UWB antenna technology was studied. A Vivaldi antenna was designed tobuild ultra-wideband antenna array. The antenna operates in0.25GHz to0.88GHzfrequency with size of420mm×220mm. A balance-unbalance convertor is designed tomatch the impedance of50ohm coaxial cable. Its time/frequency domain patterns,current distribution and the gain are simulated and analyzed.2. A method of beamforming of ultra-wideband array is studied. By setting probesto record waveform of radiation signals, ultra-wideband arrays of different scales aresimulated in both time domain and frequency domain to achieve an optimizationdistribution for two-dimensional linear array and beamforming of40degree.3. A time delayer is designed and fabricated based on Field–Programmable GateArray (FPGA) and AD9501time-delay chip which is manufactured by ADI Company. Itcan provide appropriate delay for ultra-wideband antenna unit with delay accuracy of100ps and delay range of25ns~35ns.4. The proposed4×1array is tested by experiment. There are two parts in theexperiment: with and without beam scanning. The synthesis situation in the far-fieldregion is tested when excitations of antenna units are simultaneous. When time-delay ofthe excitations of antenna units are different, the received signals of different angles away from the axis of antenna array are tested to obtain the peak-peak value pattern ofthe array. The experimental results are compared with simulation results to verify thecorrectness of each other.