| Antennas are the necessary components in any wireless systems. Their function is to transmit or to receive radio wave. Antennas transmit the guided microwave into the free space in the frond-end of a transmitter, and do an inverted transition in the frond-end of a receiver. Consequently, signals can be transmitted between two arbitrary points. In the recent years, the fast development of the wireless communication systems has brought prosperity to the antenna industry. Such as WLAN (wireless local area network), UWB and UWB band-notched antenna have been widely study, and the application of these antenna was presented. In addition, due to the demand for compact system, compact and broadband microstrip antennas have become a hotspot in the antenna industry. Compact broadband microstrip antennas, WLAN (wireless local area network), and UWB band-notched antennas were lucubrated, and several antennas possess of innovative structures were proposed in this paper.The first chapter of this thesis attached more importance on several parameters to describe the performance of antennas and methods for antenna analyzed. A brief introduction of the main work of this paper was also presented.The main content of chapter II describes the compact and broadband techniques of microstrip antenna. Through perusing a large number of papers and taking a great deal of simulation researches, several techniques to achieve compact and broadband of microstrip antenna have been summarized. The impedance bandwidths of the ordinary microstrip antennas are only 0.7%~7%. Further more, due to the radiant areas of compact microstrip antennas diminished, the radiant efficiency will become worse, then the impedance bandwidth diminished. In this chapter, the author integrated the techniques of shorted-loaded and slot-loaded, engender several resonant frequencies close to each other, then two novel compact broadband microstrip antennas were obtain. These two antennas possess characteristics of wideband, small size, and low-Profile.Chapter III introduces the design of wireless local area network (WLAN) antenna. The WLAN include two frequencies bands of 2.4-GHz (IEEE 802.11b/g, 2400-2484 MHz) and 5-GHz (IEEE 802.11a, 5150-5825 MHz). Several WLAN dual-band antennas in the references were introduced in this chapter, and techniques to achieve dual broadband WLAN antennas were also summarized. Two dual broadband WLAN antennas that designed by the author were introduced in details in the end. Possessing the traits of broadband, moderate gain, and compact structure, the antenna can be used in WLAN system.Chapter IV introduces the design of planar UWB band-notched antenna. After the FCC authorized 3.1~10.6 GHz can be commercial used for UWB (Ultra wideband) technique in 2002, then, the planar UWB antennas have become a new hotspot. However, as was presented in chapter III, the 5.15-5.825 GHz band is also used in WLAN systems. In recent years, the UWB antennas with a band-notch at 5-6 GH to avoid the interference between WLAN and UWB systems had been widely studied. In this chapter, the author briefly introduced several UWB band-notch antennas, and summarizing the techniques for band-notch design. Two novel UWB band-notched antennas that designed by the author were presented in details.Considered the length of the thesis, chapter II, III andâ…£are all of my works in the last three years except for the brief introductions of microstrip antenna, WLAN antenna, and UWB band-notched antenna. |
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