| Mobile communication systems have experienced enormous growth in recent years. Nowadays the range of mobile terminals has evolved from a single voice service to multifunctional services which include the voice, positioning, data, images et.al Bluetooth, GPS, Mobile TV, and other technologies have been applied on smart phones. As the most important radio-frequency front device, antenna featuring miniaturization, built-in, multiband and smart is under way.The goal of this paper is to design the broadband antenna for WCDMA/Bluetooth and dual-band antenna for WCDMA/GPS.Microstrip antennas have become the optimal choice for mobile terminal,due to its low-profile and multi-band implementation.The basic theory of microstrip antennas is firstly introduced in this thesis.the rectangular microstrip antenna is analyzed by using the transmission line model and cavity model.The summary and verification to.metheds and techniques which are used in antenna miniaturization, multi-band and broadband work are given out in this thesis The main research focuses on radiation principle and electrical performance of the fashionable planar inverted-F antennas (PIFA). With refering to tremendous related literatures, a novel handset terminal antenna PIFA is proposed.Based on this antenna structure, discussion is mainly concentrated on the performance which and how antenna's structural parameters are contributing to. Through synthesizing all these features, a specific design and its results are demonstrated in the thesis. The results show that this antenna has broadband characteristics and it can operate in both WCDMA and BluetoothThen the thesis discussesd the theories and realization methods of circular polarization (CP) for microstrip antennas in details.Based on the analysis, a compact circularly polarized square patch for GPS is proposed. With the help of EM simulation software HFSS, the antenna is designed and optimized.Consequently the antenna is fabricated. The simulation and testing results show that it is satisfied with GPS service requirements.Ultimately, a dual-band circularly polarized microstrip antenna with low frequency ratio is presented.Axial ratio bandwidth of the antenna is expanded by using two feedings. The antenna can operate in both GPS and WCDMA. |
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