| With the rapid development of wireless communication technologies, there are more requirements for mobile terminals used in wireless communication systems. Meanwhile, because of the importance of the antenna to the mobile terminals, there are some new requirements for the antenna such as miniaturized, broadband and multi-band. Although there are various small size antennas which can be used in mobile terminals, microstrip antennas have been widely used due to its attractive features of low profile, small size, light weight and convenience for fabrication.This thesis combines the contents of National863Project and NSFC project, and focus on the miniaturized method and multi-band technology for microstrip antenna. And a new structure of the antenna of small size is proposed. Besides, two types of low profile, multi-band and minimized antennas which can be used for mobile terminals are proposed and optimized by the theoretical analysis and the commercial high frequency electromagnetic simulation software.The main work and creative points of this thesis are summarized as follows:1. A brief summary of research status for microstrip antenna, especially for microstrip patch antenna and microstrip slot antenna is given in this thesis. And the miniaturization, broadband and multi-band technologies which are commonly used are also introduced in this thesis.2. A compact planar monopole antenna which can cover the five bands GSM850/900/DCS/PCS/UMTS is proposed. This antenna uses the combined feeding structure and has several strips then generates more than one resonant path to excite different frequency points. The technology of using a slotted patch has the ability to generate more resonant paths, and furthermore, generate more resonant frequencies. And the parameters of the antenna are optimized and defined by analyzing the influence of the resonant paths to the characters. for the antenna. The technology of using a combined feeding is employed to get a better impedance matching for the antenna. This antenna is manufactured and tested. The measured results show good agreement with the simulated results.3. For the microstrip patch antenna etched by rectangular slot, the influences of the feeding line, the ground and the slot on the imputing characteristics of the microstrip slot antenna are analyzed in this thesis. The microstrip slot antenna for WLAN802.11a and802.11b is proposed. Coupling feeding is used in this antenna, and the resonant mode of one-quarter wavelength is realized by etching the slot on the patch edge. The radiated patch is implemented on a patch with dimension of20x26mm2.. |
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