| With the rapid development of mobile communication,properties of miniaturization,broadband and multi-frequency for antennas in application of wireless communication systems are demanded.Then,with the development of mobile communication business,the communication frequencies have expanded to DCS(1710～1880MHz) frequency bands,and even the 3G business frequency bands from GSM(880～960MHz) frequency bands.Besides,the Bluetooth,wireless local area network frequency etc.are widely used.Antenna is one of the important component in wireless communication quality.The rapid development of wireless communication technology puts higher request to terminal antenna,such as ultra-thin,super-mini and multiband etc.Therefore,research on the miniaturization and multiband for antenna has great actual values.In the compact wireless communication system,microstrip antenna have been widely used for their lots of advantages,such as small size,light weight,low profile,low cost and easy to work at multiband etc.However,some shortcomings of microstrip antennas such as low gain,small bandwidth,etc,make them unfit for practical application.Composed of ground plate,short circuit patch,feeding line and ground line,the Planar Inverted F Antenna(PIFA) has the features of compact size,low profile,light weight,easy to fabricate,and easy to integrate,these properties meet the demands of the above systems,so the PIFA has been found widely applications.The basic configurations and principles of PIFA are studied.The different types of PIFAs and the advantanges and the disadvantanges of microstrip antennas are summarized.The miniaturization and multi-band technologies of the microstrip antenna are introduced.A novel internal dual-band patch antenna with a small thickness of 3mm for application in GSM/DCS mobile terminals such as the mobile phone or Personal Digital Assistant(PDA) phone is presented.The patch antenna occupies15 ~*60 mm~2,with its top patch embedded with an area of a simple T-shaped slit,which separates the top patch into two resonant paths to generate two resonant modes for 900/1800MHz operation.Then,by extending a small portion of the top patch beyond the top edge of the system ground plane of the mobile terminal,to achieve ultra slim structure.The proposed antenna is experimentally studied,and effects of the extended top-patch portion and the ground-plane length on the obtained bandwidths are discussed.Besides,a novel PIFA for 2.4/5 GHz Bluetooth and WLAN bands is presented,the hight of antenna is lower then traditional structure.Simulated results show that these antennas are suitable for current wireless communication systems. |
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