| The wireless sensor network (often called WSN for short), supposed to be an important technology in the 21st century, is a bran-new kind of wireless network. It comprises a large number of sensor nodes, which are used to detect, collect and process the real-time informations of targets in the network area. Sensor nodes are the WSN's fundamental units. They communicate these various real-time informations to each other and to users continuously. It is necessary to design a high performance antenna and its correlative circuit for every sensor node in order to consummate the node's communication function. The antenna is used to send and receive electromagnetic wave, which is the fundamental communication-link of WSN. In order to feed the antenna, achieve the conversion of balance and unbalance, and match the impedance, feed-line, balun, and impedance-matching circuit are designed and placed between the antenna and wireless communication processing unit.The main work and contributions of the thesis are as follows.(1) The structure of sensor node is expounded. The characteristics of sensor node, as well as their influence on antenna and its correlative circuit, are analyzed. The recent researchs on antenna for sensor node are presented and analyzed.(2) Several main parameters of antenna are expounded. Some kinds of antennas, feed-lines, baluns, as well as impedance-matching circuits are analyzed and compared. According to the characteristics of sensor node, monopole antenna and folded dipole antenna are the appropriate antennas, so both of them are chosen.(3) During the design process of monopole antenna, an original balun is amended and the performance of the amended balun is simulated. A lot of experiments upon the radiating performance of the antenna are carried on. The antenna and balun's performance is proved.(4) The relation between the input-impedance of a basic printed folded dipole antenna and its length is simulated and synthesized. CPS (Co-Planar Strip) is chosen as the feed-line. The basic antenna is amended to fit the characteristics of CPS. An original impedance-matching circuit is amended also. The performance and correctness of the amended antenna, feed-line, and impedance-matching circuit is simulated and proved.(5) The two kinds of antenna and its correlative circuit are compared with one another. Their advantages and disadvantages are synthesized.The work of analyzing, designing, and implementing the antenna and its correlative circuit for WSN nodes, presented in this thesis, is of great significance in designing sensor node and constructing WSN. |
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