| Ultra-wideband (UWB) technology is an attractive technology for short range and high speed wireless communication system. Antenna is a crucial part of UWB systems, and the performance of antenna can cause direct influence on the communication quality. The paper is mainly about how to design the antenna that can be used in 3.1～10.6 GHz UWB wireless communication systems. The time domain characteristics of UWB antenna array is also studied in this paper.Firstly, the parameters that evaluate the performance of UWB antennas are revealed in the paper. Two methods of study the UWB antenna by time domain characteristics are summarized, that is, transfer function measurement in frequency domain and direct measurement in time domain. Then the UWB antennas which are suitable for communication are designed and studied. The major achievements are listed as follows:In the antenna design aspect, the spatial structure of traditional volcano smoke antenna is converted to planar structure, so that the printed volcano smoke antenna is designed and studied; For the microstrip line fed circular slot antenna, three methods are used to achieve the band-notched characteristics, that is cutting slot,connecting "L-shaped" strips on the ground and inserting parasitic element; The impedance bandwidth of microstrip line fed circular slot antenna is improved, so that the application scope of the antenna is expanded; For the double printed U-shaped dipole antenna, good band-notched characteristic is obtained by connecting "L-shaped" strips on the antenna. Simulations using the EM simulator software CST and experiments are combined in the paper to design and investigate the antennas, the basic parameters as impedance bandwidth,radiation pattern and gain are studied, besides, transfer function and time domain characteristics are also investigated to discuss the special request of UWB systems.In the study of UWB antenna array aspect, fundamental model in time domain of UWB antenna array is established theoretically, the total time delay, which is one important parameter to obtain the assigned beam pointing. The time domain characteristics of even straight array and even circular array by constant-amplitude synchronism feed is investigated to provide the theory instruction for actual antenna array's design.The UWB antennas with planar structure are presented in this paper. The antennas have small size and easy to fabricate. The study works done in this paper have the vital significance to the UWB antenna theory and the technology. |
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