| WPAN(Wireless personal area network)is a kind of wireless network which is available to a specific group,and is used for small area communication.The current main technologies include Bluetooth,Zigbee,UWB(Ultra wideband),HomeRF,WiMedia and 60 GHz short distance wireless communication,which is still in rapid development.As key components in wireless communication,antennas used in the above systems are widely focused and studied in recent years.For a communication system,how to improve the communication rate and how to make the communication equipment miniaturization are focus of attention.In some WPAN,such as Bluetooth and UWB communication systems,omni-directional antennas are usually used to ensure the normal communication at any angles.Designing omnidirectional antennas which cover multiple frequency bands is one of the effective methods for this problem.In addition,60 GHz short-range wireless communication technology has also been focused.because of its rich spectrum resources,60 GHz communication systems have high communication rate.However,due to high attenuation of propagation in space,in order to expand the communication range,it is necessary to design the antenna with high gain characteristic.However,at present,researches on 60 GHz high gain antenna are far from enough.Therefore,in this paper,the main research contents on planar antennas in WPAN are as follows:1.Firstly,a dual band planar monopole antenna which can be used in the terminal equipment is designed,the antenna is fed by microstrip.The resonant characteristics of the antenna are analyzed,and the working bandwidth finally covers the Bluetooth band and the UWB band.Measured results show the antenna has omnidirectional radiation characteristics and stable gain in working band.Secondly,an omnidirectional antenna with horizontal polarization characteristic is proposed.The antenna is composed of rotating dipole array,making the antenna radiate horizontally polarized electromagnetic wave on the horizontal plane.The simulation and measurement results show the working frequency band covers Bluetooth,WiMAX and WLAN.In the working band,the antenna has flat gain and stable radiation patterns,the cross polarization is less than10 dB.2.Based on PCB technology,two directional antennas for 60 GHz wirelesscommunication are proposed.Firstly,in order to enhance the broadside gain of dipoles,we present the structure of adding two identical parasitic patches on both sides of a dipole with the same distance.the radiation characteristics of this structure are analyzed,the results show there are three kinds of radiation patterns.Then in the process of designing antenna with high gain and narrow beamwidth,this structure is reasonably utilized.Finally,by applying AMC surface,the gain in broadside direction is further improved.The antenna has a total size of 7.5mm×8mm×0.781 mm.The measured results show the working bandwidth covers 57-64 GHz,the maximum measured gain is up to 10.9 dBi,the gain fluctuation is less than 1 dB.Secondly,a planar 60 GHz antenna with wide beamwidth is presented.The antenna also use a planar dipole antenna as prototype for its wide beamwidth,after a series of deformation,the endfire radiation is enhanced.The measured results show the working banwidth covers 57-64 GHz,the beamwidth is from 142° to 153°.In the working band,the maximum measured gain is up to 10.9 dBi,and the gain fluctuation is less than 1 dB. |
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